fix(tui): include exactly-30-day sessions in the relative-age branch

The picker detail line newly renders cwd, model id, and tag, and any
of them can legally carry ESC/CSI/OSC/BEL/BS/VT/NEL bytes — a project
directory name containing \x1b[2J would repaint the terminal when the
picker opens. sanitizeCardField now maps line separators and tabs to
spaces and drops every remaining control rune, matching the package's
other sanitizers; this also closes the same hole for titles, which
predates the detail line.

docs/HOW_ZERO_WORKS.md

@@ -302,9 +302,8 @@ Conceptually, one requested tool goes through these phases:
    the model can inspect it and decide what to do next.
 6. **Render and persist** — the result is surfaced to the TUI, stream-JSON
    writer, or ACP client. TUI and exec record rich tool/session events for
-   resume/history; ACP persists conversational messages and completed tool-call
-   starts/results for load replay. Live streaming details and permission
-   exchanges remain client notifications rather than durable history.
+   resume/history; ACP currently persists conversational messages and streams
+   tool/permission updates to the client.
 
 Tool success and failure are both informative context. A successful `read_file`
 result gives the model file contents; a failed `edit_file` result gives the model

internal/acp/agent.go

@@ -2,14 +2,10 @@ package acp
 
 import (
 	"context"
-	"crypto/sha256"
 	"encoding/base64"
 	"encoding/json"
 	"errors"
-	"fmt"
 	"log"
-	"os"
-	"path/filepath"
 	"strings"
 	"sync"
 
@@ -44,12 +40,8 @@ type Deps struct {
 	// ResolveWorkspaceRoot validates + normalizes a client-supplied cwd (must be an
 	// existing directory; never the bare root). It is the file-tool confinement root.
 	ResolveWorkspaceRoot func(cwd string) (string, error)
-	// PersistEvents is an optional test seam for injecting event-store failures.
-	// It receives a COMPLETED TURN as one batch, never one event at a time: the
-	// batch is the unit the shared store keeps contiguous (see persistTurn).
-	PersistEvents func(sessionID string, inputs []sessions.AppendEventInput) error
-	Store         *sessions.Store
-	AgentInfo     Implementation
+	Store                *sessions.Store
+	AgentInfo            Implementation
 }
 
 // Workspace is the per-turn execution environment passed to the agent. ACP does
@@ -114,8 +106,6 @@ func NewAgent(conn *Conn, deps Deps) *Agent {
 	conn.Handle(MethodInitialize, a.handleInitialize)
 	conn.Handle(MethodSessionNew, a.handleSessionNew)
 	conn.Handle(MethodSessionLoad, a.handleSessionLoad)
-	conn.Handle(MethodSessionList, a.handleSessionList)
-	conn.Handle(MethodSessionResume, a.handleSessionResume)
 	conn.Handle(MethodSessionPrompt, a.handleSessionPrompt)
 	conn.Handle(MethodSessionSetMode, a.handleSetMode)
 	conn.Handle(MethodSessionSetConfigOption, a.handleSetConfigOption)
@@ -144,11 +134,11 @@ func (a *Agent) handleInitialize(_ context.Context, params json.RawMessage) (any
 	return InitializeResult{
 		ProtocolVersion: negotiated,
 		AgentCapabilities: AgentCapabilities{
-			// ACP v1 optional methods are advertised as empty capability objects;
-			// clients must gate session/list and session/resume on their presence.
-			LoadSession:         true,
-			PromptCapabilities:  PromptCapabilities{Image: true},
-			SessionCapabilities: &SessionCapabilities{List: &struct{}{}, Resume: &struct{}{}},
+			// Only advertise what ZERO actually implements: session/load (loadSession)
+			// and image prompts. session/resume + the session-capability sub-object
+			// are intentionally omitted since there is no resume handler yet.
+			LoadSession:        true,
+			PromptCapabilities: PromptCapabilities{Image: true},
 		},
 		AgentInfo: &info,
 		// ZERO owns credentials (BYOK) and does not delegate auth to the editor.
@@ -158,41 +148,12 @@ func (a *Agent) handleInitialize(_ context.Context, params json.RawMessage) (any
 
 // ---- session lifecycle ----
 
-// requestedWorkspace is the single rule for a cwd that arrived from the client,
-// applied before the value can reach ResolveWorkspaceRoot.
-//
-// THE REQUEST'S OWN CWD IS THE ONLY THING ALLOWED TO PICK A ROOT. Every params
-// type spells cwd as a plain string, so an absent field and an empty one decode
-// to exactly the same "", and the resolver treats "" as "use the directory this
-// process was started in" and joins a relative cwd onto it. Those two defaults
-// meet in the middle: `{"sessionId":"known"}` used to activate a persisted
-// session, and `{}` used to create one, both rooted at wherever the editor
-// happened to spawn `zero acp` — which then becomes the sandbox and file-tool
-// confinement root. The client never named that directory, so it is a root the
-// server invented, and ACP requires an absolute cwd on every method carrying
-// one. Rejecting here is what keeps a missing field from being answered with a
-// guess.
-func requestedWorkspace(cwd string) (string, error) {
-	trimmed := strings.TrimSpace(cwd)
-	if trimmed == "" {
-		return "", RPCError(codeInvalidParams, "cwd is required and must be an absolute path")
-	}
-	if !filepath.IsAbs(trimmed) {
-		return "", RPCError(codeInvalidParams, "cwd must be an absolute path: "+trimmed)
-	}
-	return trimmed, nil
-}
-
 func (a *Agent) handleSessionNew(ctx context.Context, params json.RawMessage) (any, error) {
 	var p NewSessionParams
 	if err := json.Unmarshal(params, &p); err != nil {
 		return nil, RPCError(codeInvalidParams, "invalid session/new params")
 	}
-	cwd, err := requestedWorkspace(p.Cwd)
-	if err != nil {
-		return nil, err
-	}
-	root, err := a.deps.ResolveWorkspaceRoot(cwd)
+	root, err := a.deps.ResolveWorkspaceRoot(p.Cwd)
 	if err != nil {
 		return nil, RPCError(codeInvalidParams, err.Error())
 	}
@@ -204,7 +165,7 @@ func (a *Agent) handleSessionNew(ctx context.Context, params json.RawMessage) (a
 	if err != nil {
 		return nil, RPCError(codeInternalError, "create session: "+err.Error())
 	}
-	sess, _ := a.registerSession(meta.SessionID, root, nil, model, models, restrictModels)
+	sess := a.registerSession(meta.SessionID, root, nil, model, models, restrictModels)
 	return NewSessionResult{
 		SessionID:     sess.id,
 		ConfigOptions: a.configOptions(sess),
@@ -217,90 +178,22 @@ func (a *Agent) handleSessionLoad(ctx context.Context, params json.RawMessage) (
 	if err := json.Unmarshal(params, &p); err != nil {
 		return nil, RPCError(codeInvalidParams, "invalid session/load params")
 	}
-	return a.activatePersistedSession(ctx, p, persistedSessionLoad)
-}
-
-func (a *Agent) handleSessionResume(ctx context.Context, params json.RawMessage) (any, error) {
-	var p ResumeSessionParams
-	if err := json.Unmarshal(params, &p); err != nil {
-		return nil, RPCError(codeInvalidParams, "invalid session/resume params")
-	}
-	return a.activatePersistedSession(ctx, p, persistedSessionResume)
-}
-
-type persistedSessionOperation uint8
-
-const (
-	persistedSessionLoad persistedSessionOperation = iota
-	persistedSessionResume
-)
-
-// activatePersistedSession restores the agent's internal conversation context
-// for both lifecycle methods. session/load additionally replays user-visible
-// history as ordered session/update notifications; session/resume deliberately
-// does not, which makes it safe for an already-rendered desktop reconnect.
-func (a *Agent) activatePersistedSession(ctx context.Context, p LoadSessionParams, operation persistedSessionOperation) (any, error) {
-	// BOTH METHODS, BEFORE ANYTHING IS LOOKED UP. session/resume shares this
-	// params type with session/load, so the wire cannot tell an omitted cwd from
-	// an empty one; the blank case used to be answered with the persisted cwd,
-	// which made {"sessionId":"known"} a complete, successful activation request.
-	// Validating here rather than in one handler is what keeps the two entry
-	// points from drifting apart.
-	cwd, err := requestedWorkspace(p.Cwd)
-	if err != nil {
-		return nil, err
-	}
 	meta, err := a.deps.Store.Get(p.SessionID)
 	if err != nil || meta == nil {
 		return nil, RPCError(codeInvalidParams, "session not found: "+p.SessionID)
 	}
-	if operation == persistedSessionResume && !sessions.IsResumableKind(meta.SessionKind) {
-		return nil, RPCError(codeInvalidParams, "session is not resumable: "+p.SessionID)
+	cwdInput := p.Cwd
+	if strings.TrimSpace(cwdInput) == "" {
+		cwdInput = meta.Cwd
 	}
-	if strings.TrimSpace(meta.Cwd) == "" {
-		return nil, RPCError(codeInvalidParams, "session has no persisted workspace: "+p.SessionID)
-	}
-	// SAME RULE ON THE WAY IN. Omitting a relative entry from the listing is not
-	// enough: a stored "." still resolves against this process's directory, so a
-	// client that hands back that same directory as its cwd would be sold the
-	// invented root as a match. A workspace that cannot be identified is not one
-	// this session can be restored into.
-	if !filepath.IsAbs(meta.Cwd) {
-		return nil, RPCError(codeInvalidParams, "session workspace is not an absolute path, so it cannot be identified: "+p.SessionID)
-	}
-	persistedRoot, err := a.deps.ResolveWorkspaceRoot(meta.Cwd)
-	if err != nil {
-		return nil, RPCError(codeInvalidParams, "persisted session workspace is unavailable: "+err.Error())
-	}
-	root, err := a.deps.ResolveWorkspaceRoot(cwd)
+	root, err := a.deps.ResolveWorkspaceRoot(cwdInput)
 	if err != nil {
 		return nil, RPCError(codeInvalidParams, err.Error())
 	}
-	// ACP session cwd is immutable. Loading history under a different root
-	// would give a conversation from one workspace access to another
-	// workspace's configuration, files, and tools.
-	if !sameWorkspace(root, persistedRoot) {
-		return nil, RPCError(codeInvalidParams, "session cwd does not match its persisted workspace")
-	}
 	// Load history BEFORE publishing the session so no concurrent prompt observes
 	// a half-initialized session (registerSession sets history under the lock and
 	// reuses an already-live session rather than orphaning its in-flight turn).
-	requireHistoryLog := operation == persistedSessionResume && meta.EventCount > 0
-	history, messages, historyWarning, historyErr := a.loadHistory(meta.SessionID, requireHistoryLog)
-	// RESUME PROMISES RESTORED CONTEXT, SO A FAILED RESTORATION IS A FAILED
-	// RESUME. historyErr used to do nothing but suppress replay and raise a
-	// warning: the session was registered and reported ready regardless, so a
-	// corrupt record or an unreadable events file left the caller holding a live,
-	// promptable session ID whose next prompt ran as a brand-new conversation
-	// under the old identity. Nothing in the response said so.
-	//
-	// Publication is now gated on restoration for resume. LOAD keeps the
-	// best-effort policy deliberately rather than by inheriting this helper: it
-	// replays what it has and warns about the rest, which is the right trade for
-	// a client rebuilding a transcript it can still scroll. Reported by @jatmn.
-	if operation == persistedSessionResume && historyErr != nil {
-		return nil, RPCError(codeInternalError, "restore session history: "+historyErr.Error())
-	}
+	history, historyErr := a.loadHistory(meta.SessionID)
 	model, models, restrictModels, err := a.resolveModelChoices(ctx, root)
 	if err != nil {
 		return nil, RPCError(codeInternalError, "config: "+err.Error())
@@ -311,36 +204,12 @@ func (a *Agent) activatePersistedSession(ctx context.Context, p LoadSessionParam
 			models = append(models, SessionConfigOptionValue{Value: persistedModel, Name: persistedModel})
 		}
 	}
-	sess, existed := a.registerSession(meta.SessionID, root, history, model, models, restrictModels)
-	if existed {
-		_, messages, historyWarning, historyErr = a.refreshSessionHistory(sess, requireHistoryLog)
-		if operation == persistedSessionResume && historyErr != nil {
-			return nil, RPCError(codeInternalError, "restore session history: "+historyErr.Error())
-		}
-	}
-	note := &notifier{conn: a.conn, sessionID: sess.id}
-	if operation == persistedSessionLoad && historyErr == nil {
-		for _, message := range messages {
-			if message.tool != nil {
-				note.send(*message.tool)
-				continue
-			}
-			note.send(replayMessageChunk(message.role, replayMessageID(message.eventID), message.content))
-		}
-	}
+	sess := a.registerSession(meta.SessionID, root, history, model, models, restrictModels)
 	a.warnPersistence(
-		note,
-		"rehydrate session compaction",
-		"Could not apply session compaction. Raw session history was restored instead.",
-		historyWarning,
-		operation == persistedSessionLoad,
-	)
-	a.warnPersistence(
-		note,
+		&notifier{conn: a.conn, sessionID: sess.id},
 		"load session history",
 		"Could not load session history. The session is open, but earlier turns may be missing until storage recovers.",
 		historyErr,
-		operation == persistedSessionLoad,
 	)
 	return LoadSessionResult{
 		ConfigOptions: a.configOptions(sess),
@@ -348,80 +217,6 @@ func (a *Agent) activatePersistedSession(ctx context.Context, p LoadSessionParam
 	}, nil
 }
 
-func (a *Agent) handleSessionList(_ context.Context, params json.RawMessage) (any, error) {
-	var p ListSessionsParams
-	if len(params) > 0 {
-		if err := json.Unmarshal(params, &p); err != nil {
-			return nil, RPCError(codeInvalidParams, "invalid session/list params")
-		}
-	}
-	if p.Cursor != "" {
-		return nil, RPCError(codeInvalidParams, "invalid session/list cursor")
-	}
-	items, err := a.deps.Store.ListResumable()
-	if err != nil {
-		return nil, RPCError(codeInternalError, "list sessions: "+err.Error())
-	}
-	// The filter is the one cwd ACP leaves optional, so a blank one means "no
-	// filter" rather than an error — but a relative one is rebased onto this
-	// process's directory exactly like the others, and would then silently answer
-	// about a workspace the client never named.
-	var cwd string
-	if strings.TrimSpace(p.Cwd) != "" {
-		filter, err := requestedWorkspace(p.Cwd)
-		if err != nil {
-			return nil, err
-		}
-		cwd, err = a.deps.ResolveWorkspaceRoot(filter)
-		if err != nil {
-			return nil, RPCError(codeInvalidParams, err.Error())
-		}
-	}
-	result := ListSessionsResult{Sessions: make([]SessionInfo, 0, len(items))}
-	for _, item := range items {
-		// EVERY ENTRY IS RESOLVED, FILTER OR NO FILTER. Listing is a menu, and
-		// every item on it has to be orderable: activatePersistedSession
-		// resolves the persisted workspace and refuses what it cannot reach, so
-		// anything this loop cannot resolve is something the client would be
-		// offered and then denied.
-		//
-		// Resolving only when a cwd filter was supplied left two shapes through —
-		// a session whose workspace has since been deleted, and a legacy entry
-		// holding a relative path, which was then reported as cwd "." even though
-		// ACP requires SessionInfo.cwd to be absolute.
-		if strings.TrimSpace(item.Cwd) == "" {
-			continue
-		}
-		// A RELATIVE PERSISTED CWD HAS NO RECOVERABLE IDENTITY. Resolving one
-		// rebases it onto wherever this ACP server happens to be running and
-		// advertises that invented absolute path as the session's workspace — so a
-		// conversation created for one project could be resumed against another
-		// project's configuration, files and tools. The original base is not
-		// knowable from the metadata, so the honest answer is to omit the entry
-		// rather than to guess at it.
-		if !filepath.IsAbs(item.Cwd) {
-			continue
-		}
-		itemRoot, err := a.deps.ResolveWorkspaceRoot(item.Cwd)
-		if err != nil {
-			continue
-		}
-		if cwd != "" && !sameWorkspace(itemRoot, cwd) {
-			continue
-		}
-		result.Sessions = append(result.Sessions, SessionInfo{
-			SessionID: item.SessionID,
-			Title:     item.Title,
-			// The RESOLVED root, not the stored string: absolute as ACP
-			// requires, and the same value the client will hand back on resume.
-			Cwd:       itemRoot,
-			UpdatedAt: item.UpdatedAt,
-			Meta:      &SessionInfoMeta{ModelID: item.ModelID, CreatedAt: item.CreatedAt},
-		})
-	}
-	return result, nil
-}
-
 // ---- prompt turn ----
 
 func (a *Agent) handleSessionPrompt(ctx context.Context, params json.RawMessage) (any, error) {
@@ -498,15 +293,6 @@ func (a *Agent) runTurn(ctx context.Context, sess *acpSession, userText string,
 			note.text("\n\n[zero warning] " + text + "\n")
 		}
 	}
-	// Buffer the complete turn until RunAgent has a valid ACP outcome. A hard run
-	// failure is an aborted turn: neither live history nor durable history may
-	// retain its user/tool prefix under an RPC error. StopCancelled is a valid
-	// outcome and commits through the same boundary below.
-	pendingEvents := make([]sessions.AppendEventInput, 0, 4)
-	queue := func(input sessions.AppendEventInput) {
-		pendingEvents = append(pendingEvents, input)
-	}
-	queue(messageEvent("user", userText))
 
 	opts := agent.Options{
 		Cwd:            sess.cwd,
@@ -521,12 +307,8 @@ func (a *Agent) runTurn(ctx context.Context, sess *acpSession, userText string,
 		Images:         images,
 		OnText:         note.text,
 		OnReasoning:    note.thought,
-		OnToolCall: func(call agent.ToolCall) {
-			queue(toolCallEvent(call))
-			note.toolCall(call)
-		},
+		OnToolCall:     note.toolCall,
 		OnToolResult: func(result agent.ToolResult) {
-			queue(toolResultEvent(result))
 			note.toolResult(result)
 			if result.Name == "update_plan" {
 				a.emitPlan(registry, note)
@@ -539,36 +321,19 @@ func (a *Agent) runTurn(ctx context.Context, sess *acpSession, userText string,
 
 	agentPrompt := buildPrompt(sess.snapshotHistory(), userText)
 	result, runErr := a.deps.RunAgent(ctx, agentPrompt, provider, opts)
-	if result.FinalAnswer != "" {
-		queue(messageEvent("assistant", result.FinalAnswer))
-	}
+
 	reason, stopErr := stopReasonFor(result, runErr)
 	if stopErr != nil {
 		return "", RPCError(codeInternalError, stopErr.Error())
 	}
-	// ONE BATCH, ONE LOCK. The outcome gate above decides WHETHER the turn is
-	// committed; the store batch decides WHICH RECORDS STAY TOGETHER relative to
-	// other writers, and these are different guarantees. Persisting the buffer
-	// one event per call took and released the store's session lock between
-	// events, so a second ACP instance holding the same session — its turnMu is
-	// its own, only the store is shared — could append its whole turn in the
-	// gap: user A, user B, answer B, answer A. Every write was individually
-	// locked and the log was valid, but a fresh load pairs prose by order and
-	// reconstructed three wrong turns from two right ones. Before this branch,
-	// persistTurn handed the user and assistant events to AppendEvents together;
-	// buffering until the outcome is known was correct, splitting the commit
-	// into singleton writes was not. The store writes a batch under one lock and
-	// one file write, which is the contiguity restored here — not a disk
-	// transaction, and not a promise about crashes mid-fsync. Reported by @jatmn.
-	persistenceErr := a.persistTurn(sess.id, pendingEvents)
-	sess.appendHistory(turnRecord{user: userText, assistant: result.FinalAnswer})
-	a.warnPersistence(
-		note,
-		"save session history",
-		"Could not save session history. This turn is available in memory, but future resume may miss it until storage recovers.",
-		persistenceErr,
-		true,
-	)
+	if err := a.persistTurn(sess, userText, result.FinalAnswer); err != nil {
+		a.warnPersistence(
+			note,
+			"save session history",
+			"Could not save session history. This turn is available in memory, but future resume may miss it until storage recovers.",
+			err,
+		)
+	}
 	return reason, nil
 }
 
@@ -827,159 +592,39 @@ func (a *Agent) configOptions(s *acpSession) []SessionConfigOption {
 
 // ---- persistence + continuity ----
 
-// persistTurn commits a completed turn's buffered events as one store batch, so
-// no other writer's records can land between them. A failure is the failure of
-// the whole batch: nothing after a failed prerequisite is appended on its own.
-func (a *Agent) persistTurn(sessionID string, inputs []sessions.AppendEventInput) error {
-	if len(inputs) == 0 {
-		return nil
-	}
-	if a.deps.PersistEvents != nil {
-		return a.deps.PersistEvents(sessionID, inputs)
-	}
+func (a *Agent) persistTurn(sess *acpSession, user, assistant string) error {
+	defer sess.appendHistory(turnRecord{user: user, assistant: assistant})
 	if a.deps.Store == nil {
 		return nil
 	}
-	_, err := a.deps.Store.AppendEvents(sessionID, inputs)
+	events := []sessions.AppendEventInput{
+		{
+			Type:    sessions.EventMessage,
+			Payload: map[string]any{"role": "user", "content": user},
+		},
+	}
+	if assistant != "" {
+		events = append(events, sessions.AppendEventInput{
+			Type:    sessions.EventMessage,
+			Payload: map[string]any{"role": "assistant", "content": assistant},
+		})
+	}
+	_, err := a.deps.Store.AppendEvents(sess.id, events)
 	return err
 }
 
-func messageEvent(role, content string) sessions.AppendEventInput {
-	return sessions.AppendEventInput{
-		Type:    sessions.EventMessage,
-		Payload: map[string]any{"role": role, "content": content},
-	}
-}
-
-func toolCallEvent(call agent.ToolCall) sessions.AppendEventInput {
-	return sessions.AppendEventInput{
-		Type: sessions.EventToolCall,
-		Payload: map[string]any{
-			"toolCallId": call.ID,
-			"name":       call.Name,
-			"arguments":  call.Arguments,
-		},
-	}
-}
-
-func toolResultEvent(result agent.ToolResult) sessions.AppendEventInput {
-	return sessions.AppendEventInput{
-		Type: sessions.EventToolResult,
-		Payload: map[string]any{
-			"toolCallId":   result.ToolCallID,
-			"name":         result.Name,
-			"status":       result.Status,
-			"output":       result.Output,
-			"changedFiles": append([]string(nil), result.ChangedFiles...),
-		},
-	}
-}
-
-// persistedMessage is one entry of the restored transcript in stored order. It
-// is either a message (role/content) or a tool-call notification (tool), never
-// both: keeping them in ONE ordered slice is what preserves the interleaving a
-// client needs to redraw the conversation as it originally happened.
-type persistedMessage struct {
-	eventID string
-	role    string
-	content string
-	// tool is set for a replayed tool call or its result, and is already in wire
-	// shape — it comes from the same toolCallStart/toolCallResult mapping the
-	// live turn uses, so a replayed tool call renders identically to a fresh one
-	// and there is no second mapping to drift out of sync.
-	tool *ToolCallUpdate
-}
-
-func (a *Agent) loadHistory(sessionID string, requireHistoryLog bool) ([]turnRecord, []persistedMessage, error, error) {
+func (a *Agent) loadHistory(sessionID string) ([]turnRecord, error) {
 	if a.deps.Store == nil {
-		return nil, nil, nil, nil
+		return nil, nil
 	}
-	// THE EFFECTIVE CONVERSATION, NOT THE RAW LOG. A compacted session keeps its
-	// original prefix on disk alongside an EventCompaction that names the events
-	// it replaced and carries their durable summary. ReadEvents hands back both,
-	// so restoring from it replayed superseded turns AND dropped the summary that
-	// replaced them — resume then seeded the next turn with context the
-	// conversation had already moved past, and load visibly resurrected
-	// transcript entries the user had seen compacted away.
-	//
-	// ReadRehydratedEvents is the projection the TUI and exec paths already use
-	// (internal/tui/session.go, internal/sessions/exec_session.go), so all three
-	// now agree on what the conversation IS. Switching readers alone is not
-	// enough: rehydration substitutes the compaction event in place of the events
-	// it replaced, so a loop that skips everything but EventMessage would drop the
-	// summary exactly as before. It is projected below. Reported by @jatmn.
-	events, eventLogPresent, err := a.deps.Store.ReadRehydratedEventsWithPresence(sessionID)
-	var rehydrateWarning error
+	events, err := a.deps.Store.ReadEvents(sessionID)
 	if err != nil {
-		rehydrateWarning = err
-		events, eventLogPresent, err = a.deps.Store.ReadEventsWithPresence(sessionID)
-		if err != nil {
-			return nil, nil, nil, err
-		}
-	}
-	if requireHistoryLog && !eventLogPresent {
-		return nil, nil, nil, fmt.Errorf("zero session %s event log is missing", sessionID)
+		return nil, err
 	}
 	var records []turnRecord
-	var messages []persistedMessage
-	activeToolCalls := make(map[string]string)
 	var pendingUser string
 	havePending := false
 	for _, e := range events {
-		if e.Type == sessions.EventCompaction {
-			// The summary stands in for the turns it replaced, so it enters the
-			// history as an assistant message: it is prior context the next turn
-			// must see, and the wire has no separate role for it.
-			raw, marshalErr := json.Marshal(e.Payload)
-			if marshalErr != nil {
-				continue
-			}
-			var payload struct {
-				Summary string `json:"summary"`
-			}
-			if json.Unmarshal(raw, &payload) != nil || strings.TrimSpace(payload.Summary) == "" {
-				continue
-			}
-			messages = append(messages, persistedMessage{
-				eventID: persistedMessageIdentity(sessionID, e),
-				role:    "assistant",
-				content: payload.Summary,
-			})
-			records = append(records, turnRecord{user: pendingUser, assistant: payload.Summary})
-			pendingUser = ""
-			havePending = false
-			continue
-		}
-		// TOOL ACTIVITY IS PART OF THE TRANSCRIPT, NOT DECORATION. A restored
-		// conversation that shows only the prose reads as if the agent asserted
-		// its edits and command output from nowhere: the user sees "I updated
-		// scope.go" with no record that any tool ran. These are collected for
-		// replay only. They deliberately do NOT enter turnRecord, so the prompt
-		// context a resumed turn receives stays byte-identical to what it was —
-		// load and resume continue to consume the SAME effective history, and
-		// only the wire rendering differs. Reported by @jatmn.
-		if e.Type == sessions.EventToolCall || e.Type == sessions.EventToolResult {
-			if upd := replayToolUpdate(e); upd != nil {
-				rawID := upd.ToolCallID
-				if e.Type == sessions.EventToolResult {
-					replayID, ok := activeToolCalls[rawID]
-					if !ok {
-						continue
-					}
-					upd.ToolCallID = replayID
-					delete(activeToolCalls, rawID)
-				} else {
-					replayID := replayToolCallID(persistedMessageIdentity(sessionID, e))
-					activeToolCalls[rawID] = replayID
-					upd.ToolCallID = replayID
-				}
-				messages = append(messages, persistedMessage{
-					eventID: persistedMessageIdentity(sessionID, e),
-					tool:    upd,
-				})
-			}
-			continue
-		}
 		if e.Type != sessions.EventMessage {
 			continue
 		}
@@ -996,14 +641,12 @@ func (a *Agent) loadHistory(sessionID string, requireHistoryLog bool) ([]turnRec
 		}
 		switch msg.Role {
 		case "user":
-			messages = append(messages, persistedMessage{eventID: persistedMessageIdentity(sessionID, e), role: msg.Role, content: msg.Content})
 			if havePending {
 				records = append(records, turnRecord{user: pendingUser})
 			}
 			pendingUser = msg.Content
 			havePending = true
 		case "assistant":
-			messages = append(messages, persistedMessage{eventID: persistedMessageIdentity(sessionID, e), role: msg.Role, content: msg.Content})
 			records = append(records, turnRecord{user: pendingUser, assistant: msg.Content})
 			pendingUser = ""
 			havePending = false
@@ -1012,89 +655,10 @@ func (a *Agent) loadHistory(sessionID string, requireHistoryLog bool) ([]turnRec
 	if havePending {
 		records = append(records, turnRecord{user: pendingUser})
 	}
-	return records, messages, rehydrateWarning, nil
+	return records, nil
 }
 
-// replayToolUpdate rebuilds the ACP notification for one stored tool event.
-//
-// The stored toolCallId is returned here as a correlation key. loadHistory maps
-// each call occurrence to a stable session-wide replay identity and applies that
-// identity to its result. Older records wrote the field as "id", so both
-// spellings are accepted — the TUI projection already does the same
-// (internal/tui/session.go).
-//
-// A record that carries no usable id is skipped rather than replayed under a
-// synthesized one: an unpairable update is worse than a missing row.
-func replayToolUpdate(event sessions.Event) *ToolCallUpdate {
-	raw, err := json.Marshal(event.Payload)
-	if err != nil {
-		return nil
-	}
-	var payload struct {
-		Name         string   `json:"name"`
-		ToolCallID   string   `json:"toolCallId"`
-		ID           string   `json:"id"`
-		Arguments    string   `json:"arguments"`
-		Status       string   `json:"status"`
-		Output       string   `json:"output"`
-		ChangedFiles []string `json:"changedFiles"`
-	}
-	if json.Unmarshal(raw, &payload) != nil {
-		return nil
-	}
-	id := payload.ToolCallID
-	if id == "" {
-		id = payload.ID
-	}
-	if id == "" {
-		return nil
-	}
-	if event.Type == sessions.EventToolCall {
-		upd := toolCallStart(agent.ToolCall{ID: id, Name: payload.Name, Arguments: payload.Arguments})
-		return &upd
-	}
-	status := tools.Status(payload.Status)
-	if status == "" {
-		status = tools.StatusOK
-	}
-	upd := toolCallResult(agent.ToolResult{
-		ToolCallID:   id,
-		Name:         payload.Name,
-		Status:       status,
-		Output:       payload.Output,
-		ChangedFiles: append([]string(nil), payload.ChangedFiles...),
-	})
-	return &upd
-}
-
-func persistedMessageIdentity(sessionID string, event sessions.Event) string {
-	if event.ID != "" {
-		return event.ID
-	}
-	return fmt.Sprintf("%s:%d", sessionID, event.Sequence)
-}
-
-// replayMessageID maps ZERO's stable event identity to a standards-shaped UUID
-// without leaking or parsing the event id on the wire. The same stored message
-// receives the same opaque id across loads, which also gives clients an exact
-// chunk boundary when two adjacent persisted messages have the same role.
-func replayMessageID(eventID string) string {
-	return replayOpaqueID("message", eventID)
-}
-
-func replayToolCallID(eventID string) string {
-	return replayOpaqueID("tool-call", eventID)
-}
-
-func replayOpaqueID(kind, eventID string) string {
-	sum := sha256.Sum256([]byte("zero-acp-" + kind + ":" + eventID))
-	b := sum[:16]
-	b[6] = (b[6] & 0x0f) | 0x50
-	b[8] = (b[8] & 0x3f) | 0x80
-	return fmt.Sprintf("%x-%x-%x-%x-%x", b[:4], b[4:6], b[6:8], b[8:10], b[10:16])
-}
-
-func (a *Agent) warnPersistence(note *notifier, action string, message string, err error, notify bool) {
+func (a *Agent) warnPersistence(note *notifier, action string, message string, err error) {
 	if err == nil {
 		return
 	}
@@ -1103,7 +667,7 @@ func (a *Agent) warnPersistence(note *notifier, action string, message string, e
 		sessionID = note.sessionID
 	}
 	log.Printf("zero acp: failed to %s for session %s: %v", action, sessionID, err)
-	if note != nil && notify {
+	if note != nil {
 		note.text("\n\n[zero warning] " + message + "\n")
 	}
 }
@@ -1150,34 +714,18 @@ func promptImages(blocks []ContentBlock) []zeroruntime.ImageBlock {
 
 // registerSession publishes a session under the agent's lock. If one is already
 // registered for id (e.g. a re-load of an in-flight session) the existing live
-// session is returned rather than orphaning its turn or resetting its mode/model.
-// The bool reports that case so persisted activation can re-read and apply disk
-// history under turnMu. history is set BEFORE first publication so no concurrent
-// prompt can read a half-initialized session.
-func (a *Agent) registerSession(id, cwd string, history []turnRecord, model string, models []SessionConfigOptionValue, restrictModels bool) (*acpSession, bool) {
+// session is returned unchanged rather than orphaning its turn or resetting its
+// mode/model. history is set BEFORE publishing so no concurrent prompt can read a
+// half-initialized session.
+func (a *Agent) registerSession(id, cwd string, history []turnRecord, model string, models []SessionConfigOptionValue, restrictModels bool) *acpSession {
 	a.mu.Lock()
 	defer a.mu.Unlock()
 	if existing := a.sessions[id]; existing != nil {
-		return existing, true
+		return existing
 	}
 	sess := &acpSession{id: id, cwd: cwd, mode: agent.PermissionModeAuto, model: model, models: models, restrictModels: restrictModels, history: history}
 	a.sessions[id] = sess
-	return sess, false
-}
-
-// refreshSessionHistory is the activation apply boundary for an already-live
-// session. The history is read while prompts are excluded, then applied to the
-// same object the prompt path uses. Re-reading here avoids overwriting a turn
-// that committed between activatePersistedSession's pre-publication read and
-// discovering that another activation had already registered the session.
-func (a *Agent) refreshSessionHistory(sess *acpSession, requireHistoryLog bool) ([]turnRecord, []persistedMessage, error, error) {
-	sess.turnMu.Lock()
-	defer sess.turnMu.Unlock()
-	history, messages, warning, err := a.loadHistory(sess.id, requireHistoryLog)
-	if err == nil {
-		sess.setHistory(history)
-	}
-	return history, messages, warning, err
+	return sess
 }
 
 func (a *Agent) session(id string) *acpSession {
@@ -1260,48 +808,8 @@ func (s *acpSession) appendHistory(rec turnRecord) {
 	s.mu.Unlock()
 }
 
-func (s *acpSession) setHistory(history []turnRecord) {
-	s.mu.Lock()
-	s.history = append([]turnRecord(nil), history...)
-	s.mu.Unlock()
-}
-
 func (s *acpSession) snapshotHistory() []turnRecord {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 	return append([]turnRecord(nil), s.history...)
 }
-
-// sameWorkspace reports whether two resolved roots name the same directory.
-//
-// STRING EQUALITY IS NOT DIRECTORY IDENTITY. ResolveWorkspaceRoot is abs plus
-// filepath.Clean plus a stat: it does not fold case and does not resolve
-// junctions, so one directory reached by two spellings produces two different
-// roots. A session persisted from the TUI was then unresumable from an editor
-// holding a different spelling of the same project folder, and session/list
-// filtered by the other spelling returned nothing — not a failed resume but an
-// invisible one, on exactly the case this feature exists for.
-//
-// filepath.EvalSymlinks is NOT the fix on Windows: it normalises a drive letter
-// but returns a junction path unchanged, so the alias survives it. Junctions need
-// no privilege, so this is ordinary rather than exotic. os.SameFile compares the
-// filesystem's own identity for the two directories, which is the question being
-// asked.
-//
-// The string comparison stays as the fast path, and a stat failure falls back to
-// it rather than widening the match — this gate refuses access to another
-// workspace's files and configuration, so an unanswerable comparison denies.
-func sameWorkspace(left, right string) bool {
-	if left == right {
-		return true
-	}
-	leftInfo, err := os.Stat(left)
-	if err != nil {
-		return false
-	}
-	rightInfo, err := os.Stat(right)
-	if err != nil {
-		return false
-	}
-	return os.SameFile(leftInfo, rightInfo)
-}

internal/acp/jsonrpc.go

@@ -89,13 +89,6 @@ type Conn struct {
 
 	handlers  map[string]HandlerFunc
 	notifiers map[string]NotifyFunc
-	// Notifications for one method are an ordered stream: session/update in
-	// particular is stateful, so dispatching every frame in an unrelated
-	// goroutine can make a later chunk overtake an earlier one. Different
-	// methods retain independent tails, keeping session/cancel responsive while
-	// an update handler is busy.
-	notifyMu    sync.Mutex
-	notifyTails map[string]chan struct{}
 
 	mu      sync.Mutex
 	nextID  int64
@@ -113,12 +106,11 @@ type Conn struct {
 // lifetime.
 func NewConn(r io.Reader, w io.Writer) *Conn {
 	return &Conn{
-		rawReader:   r,
-		w:           w,
-		handlers:    make(map[string]HandlerFunc),
-		notifiers:   make(map[string]NotifyFunc),
-		notifyTails: make(map[string]chan struct{}),
-		pending:     make(map[int64]chan rpcMessage),
+		rawReader: r,
+		w:         w,
+		handlers:  make(map[string]HandlerFunc),
+		notifiers: make(map[string]NotifyFunc),
+		pending:   make(map[int64]chan rpcMessage),
 	}
 }
 
@@ -311,7 +303,11 @@ func (c *Conn) handleLine(ctx context.Context, line []byte) {
 		}(msg)
 	case msg.isNotify():
 		if fn := c.notifiers[msg.Method]; fn != nil {
-			c.dispatchNotification(ctx, msg, fn)
+			c.wg.Add(1)
+			go func(m rpcMessage) {
+				defer c.wg.Done()
+				fn(ctx, m.Params)
+			}(msg)
 		}
 	default:
 		// Malformed frame; reply only if we can identify a request id.
@@ -321,35 +317,6 @@ func (c *Conn) handleLine(ctx context.Context, line []byte) {
 	}
 }
 
-// dispatchNotification preserves wire order within one method without making
-// unrelated notification methods wait for each other. The read loop installs
-// each tail before starting its goroutine, so goroutine scheduling cannot
-// reorder the chain it observes.
-func (c *Conn) dispatchNotification(ctx context.Context, msg rpcMessage, fn NotifyFunc) {
-	c.notifyMu.Lock()
-	previous := c.notifyTails[msg.Method]
-	done := make(chan struct{})
-	c.notifyTails[msg.Method] = done
-	c.notifyMu.Unlock()
-
-	c.wg.Add(1)
-	go func() {
-		defer c.wg.Done()
-		defer func() {
-			close(done)
-			c.notifyMu.Lock()
-			if c.notifyTails[msg.Method] == done {
-				delete(c.notifyTails, msg.Method)
-			}
-			c.notifyMu.Unlock()
-		}()
-		if previous != nil {
-			<-previous
-		}
-		fn(ctx, msg.Params)
-	}()
-}
-
 func (c *Conn) dispatchRequest(ctx context.Context, msg rpcMessage) {
 	fn := c.handlers[msg.Method]
 	if fn == nil {

internal/acp/jsonrpc_test.go

@@ -360,86 +360,6 @@ func TestConnNotification(t *testing.T) {
 	}
 }
 
-func TestConnNotificationsForOneMethodStayInWireOrder(t *testing.T) {
-	a, b, stop := connPair(t)
-	defer stop()
-
-	firstStarted := make(chan struct{})
-	releaseFirst := make(chan struct{})
-	delivered := make(chan int, 2)
-	b.HandleNotify("update", func(_ context.Context, params json.RawMessage) {
-		var in struct{ Sequence int }
-		_ = json.Unmarshal(params, &in)
-		if in.Sequence == 1 {
-			close(firstStarted)
-			<-releaseFirst
-		}
-		delivered <- in.Sequence
-	})
-
-	if err := a.Notify("update", map[string]int{"Sequence": 1}); err != nil {
-		t.Fatalf("first notify: %v", err)
-	}
-	select {
-	case <-firstStarted:
-	case <-time.After(2 * time.Second):
-		t.Fatal("first notification did not start")
-	}
-	if err := a.Notify("update", map[string]int{"Sequence": 2}); err != nil {
-		t.Fatalf("second notify: %v", err)
-	}
-	select {
-	case sequence := <-delivered:
-		t.Fatalf("notification %d overtook the blocked first notification", sequence)
-	case <-time.After(25 * time.Millisecond):
-	}
-	close(releaseFirst)
-	for want := 1; want <= 2; want++ {
-		select {
-		case got := <-delivered:
-			if got != want {
-				t.Fatalf("notification order = ...,%d; want %d", got, want)
-			}
-		case <-time.After(2 * time.Second):
-			t.Fatalf("notification %d was not delivered", want)
-		}
-	}
-}
-
-func TestConnDifferentNotificationMethodsStayConcurrent(t *testing.T) {
-	a, b, stop := connPair(t)
-	defer stop()
-
-	updateStarted := make(chan struct{})
-	releaseUpdate := make(chan struct{})
-	cancelDelivered := make(chan struct{})
-	b.HandleNotify("update", func(context.Context, json.RawMessage) {
-		close(updateStarted)
-		<-releaseUpdate
-	})
-	b.HandleNotify("cancel", func(context.Context, json.RawMessage) {
-		close(cancelDelivered)
-	})
-
-	if err := a.Notify("update", nil); err != nil {
-		t.Fatalf("update notify: %v", err)
-	}
-	select {
-	case <-updateStarted:
-	case <-time.After(2 * time.Second):
-		t.Fatal("update notification did not start")
-	}
-	if err := a.Notify("cancel", nil); err != nil {
-		t.Fatalf("cancel notify: %v", err)
-	}
-	select {
-	case <-cancelDelivered:
-	case <-time.After(2 * time.Second):
-		t.Fatal("different notification method was blocked behind update")
-	}
-	close(releaseUpdate)
-}
-
 func TestConnMethodNotFound(t *testing.T) {
 	a, _, stop := connPair(t)
 	defer stop()

internal/acp/translate.go

@@ -19,14 +19,6 @@ func agentMessageChunk(delta string) ContentChunk {
 	return ContentChunk{SessionUpdate: UpdateAgentMessageChunk, Content: TextBlock(delta)}
 }
 
-func replayMessageChunk(role, messageID, text string) ContentChunk {
-	update := UpdateAgentMessageChunk
-	if role == "user" {
-		update = UpdateUserMessageChunk
-	}
-	return ContentChunk{SessionUpdate: update, MessageID: messageID, Content: TextBlock(text)}
-}
-
 func agentThoughtChunk(delta string) ContentChunk {
 	return ContentChunk{SessionUpdate: UpdateAgentThoughtChunk, Content: TextBlock(delta)}
 }

internal/acp/types.go

@@ -12,8 +12,6 @@ const (
 	MethodAuthenticate           = "authenticate"
 	MethodSessionNew             = "session/new"
 	MethodSessionLoad            = "session/load"
-	MethodSessionList            = "session/list"
-	MethodSessionResume          = "session/resume"
 	MethodSessionPrompt          = "session/prompt"
 	MethodSessionCancel          = "session/cancel" // notification
 	MethodSessionUpdate          = "session/update" // notification (agent -> client)
@@ -64,16 +62,8 @@ type PromptCapabilities struct {
 }
 
 type AgentCapabilities struct {
-	LoadSession         bool                 `json:"loadSession"`
-	PromptCapabilities  PromptCapabilities   `json:"promptCapabilities"`
-	SessionCapabilities *SessionCapabilities `json:"sessionCapabilities,omitempty"`
-}
-
-// Empty capability objects are presence flags in ACP v1. Pointers preserve
-// the wire distinction between an advertised `{}` and an omitted capability.
-type SessionCapabilities struct {
-	List   *struct{} `json:"list,omitempty"`
-	Resume *struct{} `json:"resume,omitempty"`
+	LoadSession        bool               `json:"loadSession"`
+	PromptCapabilities PromptCapabilities `json:"promptCapabilities"`
 }
 
 type AuthMethod struct {
@@ -127,14 +117,9 @@ type McpServer struct {
 }
 
 type NewSessionParams struct {
-	Cwd        string      `json:"cwd"`
-	McpServers []McpServer `json:"mcpServers"`
-	// AdditionalDirectories is declared by the protocol and consumed nowhere in
-	// this repo yet. When it is wired up it must go through requestedWorkspace
-	// like Cwd does: these are client-supplied paths with no absoluteness rule of
-	// their own, which is the same shape as the resume-cwd hole that made
-	// {"sessionId":"known"} activate a session against this process's directory.
-	AdditionalDirectories []string `json:"additionalDirectories,omitempty"`
+	Cwd                   string      `json:"cwd"`
+	McpServers            []McpServer `json:"mcpServers"`
+	AdditionalDirectories []string    `json:"additionalDirectories,omitempty"`
 }
 
 type NewSessionResult struct {
@@ -155,39 +140,6 @@ type LoadSessionResult struct {
 	Modes         *SessionModeState     `json:"modes,omitempty"`
 }
 
-// ListSessionsParams and the following types implement ACP v1 session/list.
-// Transcript contents stay behind session/load; this method returns metadata
-// only and leaves the optional pagination cursor opaque.
-type ListSessionsParams struct {
-	Cwd    string `json:"cwd,omitempty"`
-	Cursor string `json:"cursor,omitempty"`
-}
-
-type SessionInfoMeta struct {
-	ModelID   string `json:"modelId,omitempty"`
-	CreatedAt string `json:"createdAt,omitempty"`
-}
-
-type SessionInfo struct {
-	SessionID string           `json:"sessionId"`
-	Cwd       string           `json:"cwd"`
-	Title     string           `json:"title,omitempty"`
-	UpdatedAt string           `json:"updatedAt,omitempty"`
-	Meta      *SessionInfoMeta `json:"_meta,omitempty"`
-}
-
-type ListSessionsResult struct {
-	Sessions   []SessionInfo `json:"sessions"`
-	NextCursor string        `json:"nextCursor,omitempty"`
-}
-
-// session/resume takes session/load's wire shape, so its cwd is a plain string
-// too and an omitted one decodes exactly like an empty one. Sharing the type is
-// safe only because activatePersistedSession requires an absolute cwd from the
-// request itself — nothing downstream may supply a default for either method.
-type ResumeSessionParams = LoadSessionParams
-type ResumeSessionResult = LoadSessionResult
-
 // ---- prompt turn ----
 
 type PromptParams struct {
@@ -222,7 +174,6 @@ type SessionNotification struct {
 // ContentBlock under "content"; the variant is set via SessionUpdate.
 type ContentChunk struct {
 	SessionUpdate string       `json:"sessionUpdate"`
-	MessageID     string       `json:"messageId,omitempty"`
 	Content       ContentBlock `json:"content"`
 }
 

internal/cli/daemon.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"os/exec"
 	"os/signal"
+	"path/filepath"
 	"strings"
 	"syscall"
 	"time"
@@ -146,7 +147,11 @@ func runDaemonStartDetached(paths daemon.Paths, stdout io.Writer, stderr io.Writ
 	if err != nil {
 		return writeAppError(stderr, err.Error(), exitCrash)
 	}
-	logFile, logPath, err := daemon.OpenRuntimeLog(paths)
+	if err := os.MkdirAll(filepath.Dir(paths.Socket), 0o700); err != nil {
+		return writeAppError(stderr, err.Error(), exitCrash)
+	}
+	logPath := filepath.Join(filepath.Dir(paths.Socket), "daemon.log")
+	logFile, err := os.OpenFile(logPath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o600)
 	if err != nil {
 		return writeAppError(stderr, err.Error(), exitCrash)
 	}

internal/cli/exec.go

@@ -49,14 +49,6 @@ const (
 	exitInterrupted = 130
 )
 
-// defaultExecMaxTurns is the headless tool-turn budget when no source sets one.
-// An interactive run can be continued past the shared interactive default by the
-// user; an exec run has nobody to unstick it, so evals and automation would
-// truncate mid-task at 80 turns. The ceiling is the already-justified bound —
-// still finite against a genuinely runaway loop, which the loop's empty-turn
-// guard also cuts independently of this budget.
-const defaultExecMaxTurns = config.MaxTurnsCeiling
-
 type execOutputFormat string
 type execInputFormat string
 
@@ -328,7 +320,6 @@ func runExec(args []string, stdout io.Writer, stderr io.Writer, deps appDeps) in
 		}
 		return writeExecProviderError(stdout, stderr, options.outputFormat, "provider_error", err.Error())
 	}
-	resolved.MaxTurns = execTurnBudget(resolved)
 	var displacedMaxTurns int
 	resolved.MaxTurns, displacedMaxTurns = applyProfileTurnBudget(execProfile, options.maxTurns, resolved.MaxTurns)
 	execScope, err := sandbox.NewScope(workspaceRoot, append(append([]string{}, resolved.Sandbox.AdditionalWriteRoots...), options.addDirs...))
@@ -1231,20 +1222,6 @@ func specProfileEffortFilled(effortFilled bool, specReasoningEffort string) bool
 	return effortFilled && strings.TrimSpace(specReasoningEffort) == ""
 }
 
-// execTurnBudget applies the headless default to the resolved turn budget: an
-// interactive run can be continued past the shared default by the user, but an
-// exec run has nobody to unstick it, so an unconfigured budget starts at the
-// documented ceiling instead of truncating mid-task. Explicit sources
-// (--max-turns, mode presets, ZERO_MAX_TURNS, config files) resolve as
-// MaxTurnsSet and pass through; an exec-profile budget still wins via
-// applyProfileTurnBudget afterward.
-func execTurnBudget(resolved config.ResolvedConfig) int {
-	if resolved.MaxTurnsSet {
-		return resolved.MaxTurns
-	}
-	return defaultExecMaxTurns
-}
-
 // applyProfileTurnBudget decides the run's turn budget once config is resolved.
 // The profile displaces the RESOLVED value, not the flag: a pinned budget
 // always wins and the profile backs off entirely, while an env/config budget

internal/cli/exec_test.go

@@ -1975,23 +1975,3 @@ func TestRunExecTopTierDeclineNoSwitch(t *testing.T) {
 		t.Fatalf("provider model = %q, want claude-opus-4.1", providerModels[0])
 	}
 }
-
-func TestExecTurnBudgetDefaultsToCeilingUnlessSet(t *testing.T) {
-	cases := []struct {
-		name     string
-		resolved config.ResolvedConfig
-		want     int
-	}{
-		// A headless run has no user to continue past the shared interactive
-		// default, so an unconfigured budget starts at the ceiling.
-		{"unconfigured default", config.ResolvedConfig{MaxTurns: 80, MaxTurnsSet: false}, config.MaxTurnsCeiling},
-		// A user who configured 80 on purpose (e.g. cost control in CI) keeps 80.
-		{"explicit default value", config.ResolvedConfig{MaxTurns: 80, MaxTurnsSet: true}, 80},
-		{"configured value passes through", config.ResolvedConfig{MaxTurns: 42, MaxTurnsSet: true}, 42},
-	}
-	for _, tc := range cases {
-		if got := execTurnBudget(tc.resolved); got != tc.want {
-			t.Fatalf("%s: execTurnBudget = %d, want %d", tc.name, got, tc.want)
-		}
-	}
-}

internal/config/resolver.go

@@ -166,7 +166,6 @@ func Resolve(options ResolveOptions) (ResolvedConfig, error) {
 		Providers:           providers,
 		Provider:            active,
 		MaxTurns:            cfg.MaxTurns,
-		MaxTurnsSet:         cfg.maxTurnsSet,
 		MCP:                 cfg.MCP,
 		Sandbox:             cfg.Sandbox,
 		Notify:              cfg.Notify,
@@ -235,7 +234,6 @@ func mergeConfig(dst *FileConfig, src FileConfig) {
 	}
 	if src.MaxTurns > 0 {
 		dst.MaxTurns = src.MaxTurns
-		dst.maxTurnsSet = true
 	}
 	for _, provider := range src.Providers {
 		mergeProvider(dst, provider)
@@ -296,7 +294,6 @@ func mergeProjectConfig(dst *FileConfig, src FileConfig) error {
 	}
 	if src.MaxTurns > 0 {
 		dst.MaxTurns = src.MaxTurns
-		dst.maxTurnsSet = true
 	}
 	for _, provider := range src.Providers {
 		candidate := providerMergeCandidate(*dst, provider)
@@ -609,7 +606,6 @@ func applyEnv(cfg *FileConfig, env map[string]string) {
 				n = MaxTurnsCeiling
 			}
 			cfg.MaxTurns = n
-			cfg.maxTurnsSet = true
 		}
 	}
 
@@ -730,7 +726,6 @@ func applyOverrides(cfg *FileConfig, overrides Overrides) {
 	}
 	if overrides.MaxTurns > 0 {
 		cfg.MaxTurns = overrides.MaxTurns
-		cfg.maxTurnsSet = true
 	}
 	if overrides.Sandbox.Enabled != nil {
 		cfg.Sandbox.Enabled = overrides.Sandbox.Enabled

internal/config/resolver_test.go

@@ -2252,45 +2252,3 @@ func TestResolveRejectsInvalidCrossSessionInbound(t *testing.T) {
 		t.Fatalf("error = %v", err)
 	}
 }
-
-func TestResolveReportsExplicitMaxTurns(t *testing.T) {
-	const providerJSON = `{
-		"activeProvider": "p",
-		"providers": [{"name": "p", "provider_kind": "openai-compatible", "base_url": "https://x.example/v1", "apiKey": "k", "model": "m"}]
-	}`
-	providerWithTurns := strings.Replace(providerJSON, `"activeProvider": "p"`, `"activeProvider": "p", "maxTurns": 40`, 1)
-
-	cases := []struct {
-		name string
-		opts ResolveOptions
-		set  bool
-	}{
-		{"built-in default only", ResolveOptions{
-			Overrides: Overrides{Provider: ProviderProfile{Name: "p", ProviderKind: "openai-compatible", BaseURL: "https://x.example/v1", APIKey: "k", Model: "m"}},
-		}, false},
-		{"user config", ResolveOptions{UserConfigPath: writeConfig(t, providerWithTurns)}, true},
-		{"project config", ResolveOptions{
-			UserConfigPath:    writeConfig(t, providerJSON),
-			ProjectConfigPath: writeConfig(t, `{"maxTurns": 40}`),
-		}, true},
-		{"env", ResolveOptions{
-			Env:       map[string]string{MaxTurnsEnv: "120"},
-			Overrides: Overrides{Provider: ProviderProfile{Name: "p", ProviderKind: "openai-compatible", BaseURL: "https://x.example/v1", APIKey: "k", Model: "m"}},
-		}, true},
-		{"cli override", ResolveOptions{
-			Overrides: Overrides{
-				MaxTurns: 42,
-				Provider: ProviderProfile{Name: "p", ProviderKind: "openai-compatible", BaseURL: "https://x.example/v1", APIKey: "k", Model: "m"},
-			},
-		}, true},
-	}
-	for _, tc := range cases {
-		resolved, err := Resolve(tc.opts)
-		if err != nil {
-			t.Fatalf("%s: Resolve() error = %v", tc.name, err)
-		}
-		if resolved.MaxTurnsSet != tc.set {
-			t.Fatalf("%s: MaxTurnsSet = %v, want %v (MaxTurns=%d)", tc.name, resolved.MaxTurnsSet, tc.set, resolved.MaxTurns)
-		}
-	}
-}

internal/config/types.go

@@ -364,10 +364,6 @@ type FileConfig struct {
 	LocalControl        LocalControlConfig `json:"localControl,omitempty"`
 	STT                 STTConfig          `json:"stt,omitempty"`
 	CrossSessionInbound string             `json:"crossSessionInbound,omitempty"`
-	// maxTurnsSet records that some merge source supplied a positive maxTurns —
-	// i.e. the value is configured, not the built-in default. Unexported like
-	// Tools.deferThresholdSet: merge bookkeeping, not a config key.
-	maxTurnsSet bool
 	// Extra preserves top-level fields written by newer Zero versions or
 	// extensions so a read-modify-write through this version is non-destructive.
 	Extra map[string]json.RawMessage `json:"-"`
@@ -465,15 +461,10 @@ type Overrides struct {
 }
 
 type ResolvedConfig struct {
-	ActiveProvider string
-	Providers      []ProviderProfile
-	Provider       ProviderProfile
-	MaxTurns       int
-	// MaxTurnsSet reports whether MaxTurns came from an explicit source (a
-	// config file, a provider command, ZERO_MAX_TURNS, or CLI overrides) rather
-	// than the built-in default — callers that need a different default can
-	// tell the two apart.
-	MaxTurnsSet         bool
+	ActiveProvider      string
+	Providers           []ProviderProfile
+	Provider            ProviderProfile
+	MaxTurns            int
 	MCP                 MCPConfig
 	Sandbox             SandboxConfig
 	Notify              NotifyConfig

internal/daemon/lock.go

@@ -30,35 +30,15 @@ var processAlive = osProcessAlive
 // only to enrich a contention error with the current holder's PID; the kernel
 // lock, not PID metadata, is authoritative.
 func acquireLock(path string, isAlive func(pid int) bool) (*fileLock, error) {
-	return acquireLockWith(isAlive, func() (*lockutil.FileLock, error) {
-		return lockutil.TryAcquireFileLock(path)
-	}, func() (int, error) {
-		return readPidFile(path)
-	})
-}
-
-func acquireLockRoot(root *os.Root, name, displayPath string, isAlive func(pid int) bool) (*fileLock, error) {
-	return acquireLockWith(isAlive, func() (*lockutil.FileLock, error) {
-		return lockutil.TryAcquireFileLockRoot(root, name, displayPath)
-	}, func() (int, error) {
-		return readPidFileRoot(root, name)
-	})
-}
-
-func acquireLockWith(
-	isAlive func(pid int) bool,
-	acquire func() (*lockutil.FileLock, error),
-	readPID func() (int, error),
-) (*fileLock, error) {
 	if isAlive == nil {
 		isAlive = processAlive
 	}
-	lock, err := acquire()
+	lock, err := lockutil.TryAcquireFileLock(path)
 	if err != nil {
 		if !errors.Is(err, lockutil.ErrLockHeld) {
 			return nil, err
 		}
-		pid, perr := readPID()
+		pid, perr := readPidFile(path)
 		if perr == nil && pid > 0 && isAlive(pid) {
 			return nil, fmt.Errorf("%w (pid %d)", ErrAlreadyRunning, pid)
 		}
@@ -82,15 +62,6 @@ func (l *fileLock) release() error {
 // readPidFile reads and parses the PID recorded in a lock file.
 func readPidFile(path string) (int, error) {
 	data, err := os.ReadFile(path)
-	return parsePidFile(data, err)
-}
-
-func readPidFileRoot(root *os.Root, name string) (int, error) {
-	data, err := root.ReadFile(name)
-	return parsePidFile(data, err)
-}
-
-func parsePidFile(data []byte, err error) (int, error) {
 	if err != nil {
 		return 0, err
 	}

internal/daemon/server.go

@@ -7,7 +7,6 @@ import (
 	"fmt"
 	"net"
 	"os"
-	"path/filepath"
 	"sync"
 	"time"
 )
@@ -24,23 +23,6 @@ type Server struct {
 	listener net.Listener
 	conns    map[net.Conn]struct{} // open connections, closed on Shutdown so blocked reads return
 	lock     *fileLock
-	// runtimeRoot is retained for the full default-daemon lifecycle. Every file
-	// child is addressed relative to this capability; runtimeDir is used only to
-	// verify the unavoidable AF_UNIX pathname bind still names the same object.
-	runtimeRoot *os.Root
-	runtimeDir  string
-	// socketRoot captures the directory that actually received the pathname
-	// bind. It can differ from runtimeRoot only when the configured directory is
-	// exchanged in the final pre-bind window; retaining it makes rollback target
-	// the socket that was really created rather than re-resolving the pathname.
-	socketRoot *os.Root
-	socketName string
-	// statusRoot binds status publication and shutdown cleanup to the same
-	// directory object. statusCommitted is set only after this server publishes
-	// its document, so a failed startup never removes a previous daemon's status.
-	statusRoot      *os.Root
-	statusName      string
-	statusCommitted bool
 
 	ctx    context.Context
 	cancel context.CancelFunc
@@ -59,14 +41,6 @@ type ServerOptions struct {
 	Now     func() time.Time
 	Log     func(string)
 	isAlive func(int) bool // test hook for the single-instance lock
-	// beforeStatusReplace, replaceStatusFile, and syncStatusParent are test hooks
-	// for the status-file commit boundary. nil selects production behavior.
-	beforeStatusReplace  func()
-	replaceStatusFile    func(root *os.Root, src, dst string) error
-	syncStatusParent     func(root *os.Root) error
-	afterRuntimeRootOpen func() // test hook at the default-root trust boundary
-	beforeSocketBind     func() // test hook before the final root verification
-	afterSocketPreflight func() // test hook in the unavoidable pathname-bind window
 }
 
 // NewServer validates options and builds a Server.
@@ -106,41 +80,11 @@ func (s *Server) Serve() error {
 	if err := checkSocketPathLength(s.opts.Paths.Socket); err != nil {
 		return err
 	}
-	defaultRoot, isDefault, err := openDefaultRuntimeRoot(s.opts.Paths)
-	if err != nil {
+	if err := secureSocketParent(s.opts.Paths.Socket); err != nil {
 		return err
 	}
-	if isDefault {
-		s.runtimeRoot = defaultRoot
-		s.runtimeDir = filepath.Dir(s.opts.Paths.Socket)
-		s.statusRoot = defaultRoot
-		s.statusName = filepath.Base(s.opts.Paths.Status)
-		if s.opts.afterRuntimeRootOpen != nil {
-			s.opts.afterRuntimeRootOpen()
-		}
-		if err := runtimeRootStillNamesPath(defaultRoot, s.runtimeDir); err != nil {
-			s.closeRuntimeRoots()
-			return err
-		}
-	} else {
-		if err := secureCustomRuntimeParents(s.opts.Paths); err != nil {
-			return err
-		}
-		statusRoot, err := openStatusRoot(s.opts.Paths.Status)
-		if err != nil {
-			return fmt.Errorf("daemon: open status directory: %w", err)
-		}
-		s.statusRoot = statusRoot
-		s.statusName = filepath.Base(s.opts.Paths.Status)
-	}
-	var lock *fileLock
-	if s.runtimeRoot != nil {
-		lock, err = acquireLockRoot(s.runtimeRoot, filepath.Base(s.opts.Paths.Lock), s.opts.Paths.Lock, s.opts.isAlive)
-	} else {
-		lock, err = acquireLock(s.opts.Paths.Lock, s.opts.isAlive)
-	}
+	lock, err := acquireLock(s.opts.Paths.Lock, s.opts.isAlive)
 	if err != nil {
-		s.closeRuntimeRoots()
 		return err
 	}
 	s.lock = lock
@@ -148,22 +92,7 @@ func (s *Server) Serve() error {
 
 	// A leftover socket file from an unclean exit would make Listen fail with
 	// "address already in use"; we hold the lock, so any socket here is stale.
-	if s.runtimeRoot != nil {
-		if err := s.runtimeRoot.Remove(filepath.Base(s.opts.Paths.Socket)); err != nil && !errors.Is(err, os.ErrNotExist) {
-			return fmt.Errorf("daemon: remove stale control socket: %w", err)
-		}
-		if s.opts.beforeSocketBind != nil {
-			s.opts.beforeSocketBind()
-		}
-		if err := runtimeRootStillNamesPath(s.runtimeRoot, s.runtimeDir); err != nil {
-			return err
-		}
-		if s.opts.afterSocketPreflight != nil {
-			s.opts.afterSocketPreflight()
-		}
-	} else {
-		_ = os.Remove(s.opts.Paths.Socket)
-	}
+	_ = os.Remove(s.opts.Paths.Socket)
 
 	listener, err := net.Listen("unix", s.opts.Paths.Socket)
 	if err != nil {
@@ -172,22 +101,6 @@ func (s *Server) Serve() error {
 	s.mu.Lock()
 	s.listener = listener
 	s.mu.Unlock()
-	if s.runtimeRoot != nil {
-		boundRoot, boundName, err := captureBoundSocketRoot(s.opts.Paths.Socket)
-		if err != nil {
-			_ = listener.Close()
-			return fmt.Errorf("daemon: capture bound control socket: %w", err)
-		}
-		s.socketRoot = boundRoot
-		s.socketName = boundName
-		if err := runtimeRootStillNamesPath(s.runtimeRoot, s.runtimeDir); err != nil {
-			return err
-		}
-		info, err := s.runtimeRoot.Lstat(filepath.Base(s.opts.Paths.Socket))
-		if err != nil || info.Mode()&os.ModeSocket == 0 {
-			return fmt.Errorf("daemon: bound control socket is outside the secured runtime directory")
-		}
-	}
 	// If Shutdown already fired during the bind window, close now and bail so a
 	// shutdown requested at startup is never lost (the accept loop would otherwise
 	// block forever waiting for a connection that never comes) (D4).
@@ -198,7 +111,7 @@ func (s *Server) Serve() error {
 		return nil
 	default:
 	}
-	if err := s.hardenSocket(); err != nil {
+	if err := hardenSocketFile(s.opts.Paths.Socket); err != nil {
 		return fmt.Errorf("daemon: harden control socket: %w", err)
 	}
 	s.startedAt = s.opts.Now()
@@ -277,56 +190,11 @@ func (s *Server) cleanup() {
 	if s.listener != nil {
 		_ = s.listener.Close()
 	}
-	if s.socketRoot != nil {
-		if err := s.socketRoot.Remove(s.socketName); err != nil && !errors.Is(err, os.ErrNotExist) {
-			s.logf("daemon: remove control socket: %v", err)
-		}
-	} else if s.runtimeRoot != nil {
-		if err := s.runtimeRoot.Remove(filepath.Base(s.opts.Paths.Socket)); err != nil && !errors.Is(err, os.ErrNotExist) {
-			s.logf("daemon: remove control socket: %v", err)
-		}
-	} else {
-		_ = os.Remove(s.opts.Paths.Socket)
-	}
-	if s.statusRoot != nil {
-		if s.statusCommitted {
-			if err := s.statusRoot.Remove(s.statusName); err != nil && !errors.Is(err, os.ErrNotExist) {
-				s.logf("daemon: remove status file: %v", err)
-			}
-		}
-	}
+	_ = os.Remove(s.opts.Paths.Socket)
+	_ = os.Remove(s.opts.Paths.Status)
 	if s.lock != nil {
 		_ = s.lock.release()
 	}
-	s.closeRuntimeRoots()
-}
-
-func (s *Server) hardenSocket() error {
-	if s.runtimeRoot != nil {
-		return hardenSocketFileRoot(s.runtimeRoot, filepath.Base(s.opts.Paths.Socket))
-	}
-	return hardenSocketFile(s.opts.Paths.Socket)
-}
-
-func (s *Server) closeRuntimeRoots() {
-	if s.socketRoot != nil {
-		if err := s.socketRoot.Close(); err != nil {
-			s.logf("daemon: close bound socket directory: %v", err)
-		}
-	}
-	s.socketRoot = nil
-	if s.statusRoot != nil && s.statusRoot != s.runtimeRoot {
-		if err := s.statusRoot.Close(); err != nil {
-			s.logf("daemon: close status directory: %v", err)
-		}
-	}
-	s.statusRoot = nil
-	if s.runtimeRoot != nil {
-		if err := s.runtimeRoot.Close(); err != nil {
-			s.logf("daemon: close runtime directory: %v", err)
-		}
-	}
-	s.runtimeRoot = nil
 }
 
 func (s *Server) writeStatusFile() error {
@@ -340,30 +208,7 @@ func (s *Server) writeStatusFile() error {
 	if err != nil {
 		return err
 	}
-	root := s.statusRoot
-	ownedRoot := false
-	if root == nil {
-		var err error
-		root, err = openStatusRoot(s.opts.Paths.Status)
-		if err != nil {
-			return fmt.Errorf("daemon: write status file: %w", err)
-		}
-		ownedRoot = true
-	}
-	committed, err := writeStatusFileAtomicallyRoot(root, filepath.Base(s.opts.Paths.Status), data, 0o600, s.opts.beforeStatusReplace, s.opts.replaceStatusFile, s.opts.syncStatusParent)
-	if ownedRoot {
-		if closeErr := root.Close(); closeErr != nil {
-			err = errors.Join(err, fmt.Errorf("close status directory: %w", closeErr))
-		}
-	}
-	if committed {
-		s.statusCommitted = true
-	}
-	if err != nil {
-		if committed {
-			s.logf("daemon: status file publication committed with warning: %v", err)
-			return nil
-		}
+	if err := os.WriteFile(s.opts.Paths.Status, data, 0o600); err != nil {
 		return fmt.Errorf("daemon: write status file: %w", err)
 	}
 	return nil

internal/daemon/server_test.go

@@ -2,201 +2,20 @@ package daemon
 
 import (
 	"errors"
-	"net"
 	"os"
 	"path/filepath"
-	"runtime"
-	"strings"
 	"testing"
 	"time"
-
-	"github.com/Gitlawb/zero/internal/observability"
 )
 
-func TestServeSupportsReadOnlyCustomRuntimeDirectory(t *testing.T) {
-	if runtime.GOOS == "windows" {
-		t.Skip("Unix permission compatibility regression")
-	}
-	dir, err := os.MkdirTemp("/tmp", "zero-serve-")
-	if err != nil {
-		t.Fatal(err)
-	}
-	t.Cleanup(func() { _ = os.RemoveAll(dir) })
-	if err := os.Chmod(dir, 0o755); err != nil {
-		t.Fatal(err)
-	}
-	paths := Paths{
-		Socket: filepath.Join(dir, "daemon.sock"),
-		Lock:   filepath.Join(dir, "daemon.lock"),
-		Status: filepath.Join(dir, "daemon.status"),
-	}
-	launcher, _ := seqLauncher(&fakeWorker{pid: 1})
-	srv := newTestServerWithPaths(t, launcher, paths)
-	serveErr := make(chan error, 1)
-	go func() { serveErr <- srv.Serve() }()
-	waitForFile(t, paths.Status)
-	srv.Shutdown()
-	if err := <-serveErr; err != nil {
-		t.Fatalf("Serve with 0755 custom runtime directory: %v", err)
-	}
-	info, err := os.Stat(dir)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if got := info.Mode().Perm(); got != 0o755 {
-		t.Fatalf("custom runtime directory permissions = %04o, want unchanged 0755", got)
-	}
-}
-
-func TestServeKeepsDefaultRootBoundAcrossCoordination(t *testing.T) {
-	if runtime.GOOS == "windows" {
-		t.Skip("Windows may deny renaming a directory with an open AF_UNIX lifecycle handle")
-	}
-	home, err := os.MkdirTemp("/tmp", "zero-root-")
-	if err != nil {
-		t.Fatal(err)
-	}
-	t.Cleanup(func() { _ = os.RemoveAll(home) })
-	t.Setenv("HOME", home)
-	t.Setenv("USERPROFILE", home)
-	t.Setenv("XDG_RUNTIME_DIR", "")
-	paths, err := DefaultPaths()
-	if err != nil {
-		t.Fatal(err)
-	}
-	dir := filepath.Dir(paths.Socket)
-	moved := filepath.Join(home, "bound-runtime")
-	if err := os.Mkdir(dir, 0o700); err != nil {
-		t.Fatal(err)
-	}
-	launcher, _ := seqLauncher(&fakeWorker{pid: 1})
-	srv := newTestServerWithPaths(t, launcher, paths)
-	srv.opts.beforeSocketBind = func() {
-		if err := os.Rename(dir, moved); err != nil {
-			t.Fatal(err)
-		}
-		if err := os.Mkdir(dir, 0o700); err != nil {
-			t.Fatal(err)
-		}
-	}
-
-	err = srv.Serve()
-	if err == nil || !strings.Contains(err.Error(), "changed after it was secured") {
-		t.Fatalf("Serve error = %v, want replaced-runtime rejection", err)
-	}
-	if _, err := os.Stat(filepath.Join(moved, filepath.Base(paths.Lock))); err != nil {
-		t.Fatalf("rooted lock was not created in the bound directory: %v", err)
-	}
-	for _, path := range []string{paths.Lock, paths.Socket, paths.Status} {
-		if _, err := os.Lstat(path); !errors.Is(err, os.ErrNotExist) {
-			t.Fatalf("substitute runtime entry %s was touched: %v", path, err)
-		}
-	}
-}
-
-func TestServeRemovesSocketBoundAfterFinalRuntimeSwap(t *testing.T) {
-	if runtime.GOOS == "windows" {
-		t.Skip("Windows may deny renaming a directory with an open AF_UNIX lifecycle handle")
-	}
-	home, err := os.MkdirTemp("/tmp", "zero-bind-swap-")
-	if err != nil {
-		t.Fatal(err)
-	}
-	t.Cleanup(func() { _ = os.RemoveAll(home) })
-	t.Setenv("HOME", home)
-	t.Setenv("USERPROFILE", home)
-	t.Setenv("XDG_RUNTIME_DIR", "")
-	paths, err := DefaultPaths()
-	if err != nil {
-		t.Fatal(err)
-	}
-	dir := filepath.Dir(paths.Socket)
-	moved := filepath.Join(home, "trusted-runtime")
-	if err := os.Mkdir(dir, 0o700); err != nil {
-		t.Fatal(err)
-	}
-	launcher, _ := seqLauncher(&fakeWorker{pid: 1})
-	srv := newTestServerWithPaths(t, launcher, paths)
-	srv.opts.afterSocketPreflight = func() {
-		if err := os.Rename(dir, moved); err != nil {
-			t.Fatal(err)
-		}
-		if err := os.Mkdir(dir, 0o700); err != nil {
-			t.Fatal(err)
-		}
-	}
-
-	err = srv.Serve()
-	if err == nil || !strings.Contains(err.Error(), "changed after it was secured") {
-		t.Fatalf("Serve error = %v, want post-bind runtime replacement rejection", err)
-	}
-	if _, err := os.Stat(filepath.Join(moved, filepath.Base(paths.Lock))); err != nil {
-		t.Fatalf("rooted lock was not retained in the trusted directory: %v", err)
-	}
-	if _, err := os.Lstat(paths.Socket); !errors.Is(err, os.ErrNotExist) {
-		t.Fatalf("substitute runtime retained stale socket: %v", err)
-	}
-	listener, err := net.Listen("unix", paths.Socket)
-	if err != nil {
-		t.Fatalf("substitute runtime remained unbindable after rollback: %v", err)
-	}
-	if err := listener.Close(); err != nil {
-		t.Fatal(err)
-	}
-}
-
-func TestOpenRuntimeLogHardensDefaultRootBeforeOpen(t *testing.T) {
-	if runtime.GOOS == "windows" {
-		t.Skip("Windows DACL hardening has platform-specific coverage")
-	}
-	home := t.TempDir()
-	t.Setenv("HOME", home)
-	t.Setenv("USERPROFILE", home)
-	t.Setenv("XDG_RUNTIME_DIR", "")
-	paths, err := DefaultPaths()
-	if err != nil {
-		t.Fatal(err)
-	}
-	dir := filepath.Dir(paths.Socket)
-	if err := os.MkdirAll(dir, 0o777); err != nil {
-		t.Fatal(err)
-	}
-	if err := os.Chmod(dir, 0o777); err != nil {
-		t.Fatal(err)
-	}
-	file, logPath, err := OpenRuntimeLog(paths)
-	if err != nil {
-		t.Fatalf("OpenRuntimeLog: %v", err)
-	}
-	if err := file.Close(); err != nil {
-		t.Fatal(err)
-	}
-	if logPath != filepath.Join(dir, "daemon.log") {
-		t.Fatalf("log path = %q", logPath)
-	}
-	info, err := os.Stat(dir)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if got := info.Mode().Perm(); got&0o077 != 0 {
-		t.Fatalf("default runtime directory permissions = %04o, want owner-only", got)
-	}
-}
-
 func newTestServer(t *testing.T, launcher Launcher) (*Server, Paths) {
 	t.Helper()
 	dir := t.TempDir()
-	secureStatusTestDir(t, dir)
 	paths := Paths{
 		Socket: filepath.Join(dir, "d.sock"),
 		Lock:   filepath.Join(dir, "d.lock"),
 		Status: filepath.Join(dir, "d.status"),
 	}
-	return newTestServerWithPaths(t, launcher, paths), paths
-}
-
-func newTestServerWithPaths(t *testing.T, launcher Launcher, paths Paths) *Server {
-	t.Helper()
 	pool, err := NewPool(PoolOptions{Size: 2, Launcher: launcher, KillTimeout: 200 * time.Millisecond})
 	if err != nil {
 		t.Fatalf("NewPool: %v", err)
@@ -209,7 +28,7 @@ func newTestServerWithPaths(t *testing.T, launcher Launcher, paths Paths) *Serve
 	if err != nil {
 		t.Fatalf("NewServer: %v", err)
 	}
-	return srv
+	return srv, paths
 }
 
 func waitForFile(t *testing.T, path string) {
@@ -317,153 +136,6 @@ func TestServerEndToEnd(t *testing.T) {
 	}
 }
 
-func TestServePreservesPreviousStatusWhenReplacementFails(t *testing.T) {
-	launcher, _ := seqLauncher(&fakeWorker{pid: 1, exitCode: 0})
-	dir, err := os.MkdirTemp("", "zero-daemon-status-")
-	if err != nil {
-		t.Fatal(err)
-	}
-	t.Cleanup(func() { _ = os.RemoveAll(dir) })
-	secureStatusTestDir(t, dir)
-	paths := Paths{Socket: filepath.Join(dir, "d.sock"), Lock: filepath.Join(dir, "d.lock"), Status: filepath.Join(dir, "d.status")}
-	srv := newTestServerWithPaths(t, launcher, paths)
-	previous := []byte(`{"pid":7,"socket":"previous","version":1}`)
-	if err := os.WriteFile(paths.Status, previous, 0o600); err != nil {
-		t.Fatal(err)
-	}
-	srv.opts.replaceStatusFile = func(*os.Root, string, string) error {
-		return errors.New("injected replacement failure")
-	}
-
-	if err := srv.Serve(); err == nil || !strings.Contains(err.Error(), "injected replacement failure") {
-		t.Fatal("Serve succeeded despite injected status replacement failure")
-	}
-	got, err := os.ReadFile(paths.Status)
-	if err != nil {
-		t.Fatalf("previous status was removed after failed publication: %v", err)
-	}
-	if string(got) != string(previous) {
-		t.Fatalf("previous status changed after failed publication: %q", got)
-	}
-}
-
-func TestServeCleansStatusThroughBoundDirectoryAfterSwap(t *testing.T) {
-	if runtime.GOOS == "windows" {
-		t.Skip("Windows does not permit renaming the directory containing the live socket")
-	}
-	parent, err := os.MkdirTemp("", "zero-daemon-swap-")
-	if err != nil {
-		t.Fatal(err)
-	}
-	t.Cleanup(func() { _ = os.RemoveAll(parent) })
-	dir := filepath.Join(parent, "live")
-	movedDir := filepath.Join(parent, "moved")
-	if err := os.Mkdir(dir, 0o700); err != nil {
-		t.Fatal(err)
-	}
-	secureStatusTestDir(t, dir)
-	paths := Paths{
-		Socket: filepath.Join(dir, "d.sock"),
-		Lock:   filepath.Join(dir, "d.lock"),
-		Status: filepath.Join(dir, "d.status"),
-	}
-	launcher, _ := seqLauncher(&fakeWorker{pid: 1, exitCode: 0})
-	srv := newTestServerWithPaths(t, launcher, paths)
-	substitute := []byte(`{"pid":999,"socket":"substitute"}`)
-	srv.opts.beforeStatusReplace = func() {
-		if err := os.Rename(dir, movedDir); err != nil {
-			t.Fatalf("move status directory: %v", err)
-		}
-		if err := os.Mkdir(dir, 0o700); err != nil {
-			t.Fatalf("create substitute directory: %v", err)
-		}
-		if err := os.WriteFile(paths.Status, substitute, 0o600); err != nil {
-			t.Fatalf("write substitute status: %v", err)
-		}
-	}
-
-	serveErr := make(chan error, 1)
-	go func() { serveErr <- srv.Serve() }()
-	waitForFile(t, filepath.Join(movedDir, "d.status"))
-	srv.Shutdown()
-	select {
-	case err := <-serveErr:
-		if err != nil {
-			t.Fatalf("Serve: %v", err)
-		}
-	case <-time.After(3 * time.Second):
-		t.Fatal("Serve did not return after shutdown")
-	}
-	if _, err := os.Stat(filepath.Join(movedDir, "d.status")); !errors.Is(err, os.ErrNotExist) {
-		t.Fatalf("bound status survived cleanup: %v", err)
-	}
-	got, err := os.ReadFile(paths.Status)
-	if err != nil {
-		t.Fatalf("substitute status was removed by pathname cleanup: %v", err)
-	}
-	if string(got) != string(substitute) {
-		t.Fatalf("substitute status changed during cleanup: %q", got)
-	}
-}
-
-func TestServerPublishesDefaultStatusAfterCrashReportCreatesRuntimeDirectory(t *testing.T) {
-	home, err := os.MkdirTemp("", "zero-home-")
-	if err != nil {
-		t.Fatal(err)
-	}
-	t.Cleanup(func() { _ = os.RemoveAll(home) })
-	t.Setenv("HOME", home)
-	t.Setenv("USERPROFILE", home)
-	t.Setenv("XDG_RUNTIME_DIR", "")
-
-	if _, err := observability.WriteCrashReport(
-		observability.DefaultCrashDir(),
-		"cli",
-		"boom",
-		[]byte("stack"),
-		time.Now(),
-	); err != nil {
-		t.Fatalf("WriteCrashReport: %v", err)
-	}
-	paths, err := DefaultPaths()
-	if err != nil {
-		t.Fatalf("DefaultPaths: %v", err)
-	}
-	if paths.Status != filepath.Join(home, ".zero", "daemon.status") {
-		t.Fatalf("default status path = %q, want path beneath temporary home", paths.Status)
-	}
-
-	launcher, _ := seqLauncher(&fakeWorker{pid: 1})
-	srv := newTestServerWithPaths(t, launcher, paths)
-	serveErr := make(chan error, 1)
-	go func() { serveErr <- srv.Serve() }()
-
-	deadline := time.NewTimer(3 * time.Second)
-	defer deadline.Stop()
-	for {
-		if _, err := os.Stat(paths.Status); err == nil {
-			break
-		}
-		select {
-		case err := <-serveErr:
-			t.Fatalf("Serve returned before publishing status: %v", err)
-		case <-deadline.C:
-			t.Fatal("daemon did not publish its default status file")
-		case <-time.After(2 * time.Millisecond):
-		}
-	}
-
-	srv.Shutdown()
-	select {
-	case err := <-serveErr:
-		if err != nil {
-			t.Fatalf("Serve returned error: %v", err)
-		}
-	case <-time.After(3 * time.Second):
-		t.Fatal("Serve did not return after shutdown")
-	}
-}
-
 func TestServerSecondInstanceFails(t *testing.T) {
 	block := make(chan struct{})
 	defer close(block)

internal/daemon/socket.go

@@ -1,12 +1,9 @@
 package daemon
 
 import (
-	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
-
-	"github.com/Gitlawb/zero/internal/privatedir"
 )
 
 // maxUnixSocketPath bounds the socket path to the smallest platform sun_path
@@ -15,182 +12,10 @@ import (
 // safe cross-platform ceiling.
 const maxUnixSocketPath = 103
 
-func secureCustomRuntimeParents(paths Paths) error {
-	parents := []struct {
-		name string
-		path string
-	}{
-		{name: "socket", path: filepath.Dir(paths.Socket)},
-		{name: "lock", path: filepath.Dir(paths.Lock)},
-		{name: "status", path: filepath.Dir(paths.Status)},
-	}
-	seen := make(map[string]struct{}, len(parents))
-	for _, parent := range parents {
-		absolute, err := filepath.Abs(parent.path)
-		if err != nil {
-			return fmt.Errorf("daemon: resolve %s directory: %w", parent.name, err)
-		}
-		if _, ok := seen[absolute]; ok {
-			continue
-		}
-		seen[absolute] = struct{}{}
-		if err := os.MkdirAll(absolute, 0o700); err != nil {
-			return fmt.Errorf("daemon: create %s directory: %w", parent.name, err)
-		}
-		root, err := os.OpenRoot(absolute)
-		if err != nil {
-			return fmt.Errorf("daemon: open custom %s directory: %w", parent.name, err)
-		}
-		validateErr := validateStatusRoot(root)
-		closeErr := root.Close()
-		if validateErr != nil {
-			return fmt.Errorf("daemon: validate custom %s directory: %w", parent.name, validateErr)
-		}
-		if closeErr != nil {
-			return fmt.Errorf("daemon: close custom %s directory: %w", parent.name, closeErr)
-		}
-	}
-	return nil
-}
-
-// OpenRuntimeLog secures the default runtime root before acquiring the
-// detached daemon's log descriptor. Custom endpoint layouts remain supported,
-// but their existing parent permissions are caller-owned and left untouched.
-func OpenRuntimeLog(paths Paths) (*os.File, string, error) {
-	logPath := filepath.Join(filepath.Dir(paths.Socket), "daemon.log")
-	root, isDefault, err := openDefaultRuntimeRoot(paths)
-	if err != nil {
-		return nil, logPath, err
-	}
-	if isDefault {
-		defer root.Close()
-		file, err := openRootAppendRegular(root, filepath.Base(logPath))
-		if err != nil {
-			return nil, logPath, fmt.Errorf("daemon: open runtime log: %w", err)
-		}
-		return file, logPath, nil
-	}
-
-	parent := filepath.Dir(logPath)
-	if err := os.MkdirAll(parent, 0o700); err != nil {
-		return nil, logPath, fmt.Errorf("daemon: create custom log directory: %w", err)
-	}
-	info, err := os.Lstat(logPath)
-	if err == nil && !info.Mode().IsRegular() {
-		return nil, logPath, fmt.Errorf("daemon: custom runtime log is not a regular file")
-	}
-	if err != nil && !errors.Is(err, os.ErrNotExist) {
-		return nil, logPath, fmt.Errorf("daemon: inspect custom runtime log: %w", err)
-	}
-	file, err := os.OpenFile(logPath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o600)
-	if err != nil {
-		return nil, logPath, fmt.Errorf("daemon: open custom runtime log: %w", err)
-	}
-	return file, logPath, nil
-}
-
-func openDefaultRuntimeRoot(paths Paths) (*os.Root, bool, error) {
-	defaults, err := DefaultPaths()
-	if err != nil {
-		// A caller-supplied layout remains usable even when the process has no
-		// resolvable home directory. Production default paths can only reach this
-		// helper after DefaultPaths has already succeeded.
-		return nil, false, nil
-	}
-	matches, err := samePaths(paths, defaults)
-	if err != nil {
-		return nil, false, err
-	}
-	if !matches {
-		return nil, false, nil
-	}
-	root, err := privatedir.Open(filepath.Dir(defaults.Socket))
-	if err != nil {
-		return nil, false, fmt.Errorf("daemon: secure default runtime directory: %w", err)
-	}
-	return root, true, nil
-}
-
-func samePaths(left, right Paths) (bool, error) {
-	pairs := [][2]string{
-		{left.Socket, right.Socket},
-		{left.Lock, right.Lock},
-		{left.Status, right.Status},
-	}
-	for _, pair := range pairs {
-		leftAbs, err := filepath.Abs(pair[0])
-		if err != nil {
-			return false, fmt.Errorf("daemon: resolve runtime path: %w", err)
-		}
-		rightAbs, err := filepath.Abs(pair[1])
-		if err != nil {
-			return false, fmt.Errorf("daemon: resolve default runtime path: %w", err)
-		}
-		if filepath.Clean(leftAbs) != filepath.Clean(rightAbs) {
-			return false, nil
-		}
-	}
-	return true, nil
-}
-
-func runtimeRootStillNamesPath(root *os.Root, path string) error {
-	opened, err := root.Stat(".")
-	if err != nil {
-		return fmt.Errorf("inspect bound runtime directory: %w", err)
-	}
-	current, err := os.Lstat(path)
-	if err != nil {
-		return fmt.Errorf("inspect runtime directory entry: %w", err)
-	}
-	if current.Mode()&os.ModeSymlink != 0 || !os.SameFile(opened, current) {
-		return fmt.Errorf("daemon: default runtime directory changed after it was secured")
-	}
-	return nil
-}
-
-func captureBoundSocketRoot(path string) (*os.Root, string, error) {
-	root, err := os.OpenRoot(filepath.Dir(path))
-	if err != nil {
-		return nil, "", fmt.Errorf("open bound socket directory: %w", err)
-	}
-	name := filepath.Base(path)
-	info, err := root.Lstat(name)
-	if err != nil {
-		_ = root.Close()
-		return nil, "", fmt.Errorf("inspect bound socket: %w", err)
-	}
-	if info.Mode()&os.ModeSocket == 0 {
-		_ = root.Close()
-		return nil, "", fmt.Errorf("bound socket path is not a socket")
-	}
-	return root, name, nil
-}
-
-func openRootAppendRegular(root *os.Root, name string) (*os.File, error) {
-	info, err := root.Lstat(name)
-	if errors.Is(err, os.ErrNotExist) {
-		return root.OpenFile(name, os.O_CREATE|os.O_EXCL|os.O_WRONLY|os.O_APPEND, 0o600)
-	}
-	if err != nil {
-		return nil, err
-	}
-	if !info.Mode().IsRegular() {
-		return nil, fmt.Errorf("runtime log is not a regular file")
-	}
-	file, err := root.OpenFile(name, os.O_WRONLY|os.O_APPEND, 0o600)
-	if err != nil {
-		return nil, err
-	}
-	opened, err := file.Stat()
-	if err != nil {
-		_ = file.Close()
-		return nil, err
-	}
-	if !opened.Mode().IsRegular() {
-		_ = file.Close()
-		return nil, fmt.Errorf("runtime log changed while opening")
-	}
-	return file, nil
+// secureSocketParent creates the socket's parent directory owner-only (0700 on
+// POSIX; on Windows the per-user profile directory is already ACL-restricted).
+func secureSocketParent(socketPath string) error {
+	return os.MkdirAll(filepath.Dir(socketPath), 0o700)
 }
 
 // checkSocketPathLength rejects an over-long unix socket path before bind.

internal/daemon/socket_posix.go

@@ -10,7 +10,3 @@ import "os"
 func hardenSocketFile(path string) error {
 	return os.Chmod(path, 0o600)
 }
-
-func hardenSocketFileRoot(root *os.Root, name string) error {
-	return root.Chmod(name, 0o600)
-}

internal/daemon/socket_windows.go

@@ -2,12 +2,8 @@
 
 package daemon
 
-import "os"
-
 // hardenSocketFile is a no-op on Windows: AF_UNIX socket files do not honor POSIX
 // mode bits, and the daemon places the socket under the per-user profile
 // directory, which is already ACL-restricted to the owner. A dedicated restricted
 // ACL (or a named pipe with an explicit DACL) is a documented follow-up.
 func hardenSocketFile(string) error { return nil }
-
-func hardenSocketFileRoot(*os.Root, string) error { return nil }

internal/daemon/status_dir_owner_unix.go

@@ -1,20 +0,0 @@
-//go:build !windows
-
-package daemon
-
-import (
-	"fmt"
-	"os"
-	"syscall"
-)
-
-func checkStatusDirOwner(_ *os.Root, info os.FileInfo) error {
-	stat, ok := info.Sys().(*syscall.Stat_t)
-	if !ok {
-		return fmt.Errorf("status directory ownership metadata is unavailable")
-	}
-	if int(stat.Uid) != os.Geteuid() {
-		return fmt.Errorf("status directory is owned by uid %d, not the current user", stat.Uid)
-	}
-	return nil
-}

internal/daemon/status_dir_owner_unix_test.go

@@ -1,51 +0,0 @@
-//go:build !windows
-
-package daemon
-
-import (
-	"os"
-	"strings"
-	"syscall"
-	"testing"
-	"time"
-)
-
-func secureStatusTestDirPlatform(t *testing.T, dir string) {
-	t.Helper()
-	if err := os.Chmod(dir, 0o700); err != nil {
-		t.Fatal(err)
-	}
-}
-
-func broadenStatusTestDirPlatform(t *testing.T, dir string) {
-	t.Helper()
-	if err := os.Chmod(dir, 0o755); err != nil {
-		t.Fatal(err)
-	}
-}
-
-func TestCheckStatusDirOwnerRejectsMissingMetadata(t *testing.T) {
-	err := checkStatusDirOwner(nil, statusDirOwnerTestInfo{})
-	if err == nil || !strings.Contains(err.Error(), "metadata is unavailable") {
-		t.Fatalf("checkStatusDirOwner error = %v, want unavailable metadata rejection", err)
-	}
-}
-
-func TestCheckStatusDirOwnerRejectsDifferentUser(t *testing.T) {
-	info := statusDirOwnerTestInfo{sys: &syscall.Stat_t{Uid: uint32(os.Geteuid() + 1)}}
-	err := checkStatusDirOwner(nil, info)
-	if err == nil || !strings.Contains(err.Error(), "not the current user") {
-		t.Fatalf("checkStatusDirOwner error = %v, want owner mismatch rejection", err)
-	}
-}
-
-type statusDirOwnerTestInfo struct {
-	sys any
-}
-
-func (statusDirOwnerTestInfo) Name() string       { return "." }
-func (statusDirOwnerTestInfo) Size() int64        { return 0 }
-func (statusDirOwnerTestInfo) Mode() os.FileMode  { return os.ModeDir | 0o700 }
-func (statusDirOwnerTestInfo) ModTime() time.Time { return time.Time{} }
-func (statusDirOwnerTestInfo) IsDir() bool        { return true }
-func (info statusDirOwnerTestInfo) Sys() any      { return info.sys }

internal/daemon/status_dir_owner_windows.go

@@ -1,137 +0,0 @@
-//go:build windows
-
-package daemon
-
-import (
-	"errors"
-	"fmt"
-	"os"
-	"unsafe"
-
-	"golang.org/x/sys/windows"
-)
-
-const statusDirectoryWriteAccess = windows.ACCESS_MASK(
-	windows.GENERIC_ALL |
-		windows.GENERIC_WRITE |
-		windows.DELETE |
-		windows.WRITE_DAC |
-		windows.WRITE_OWNER |
-		windows.FILE_WRITE_DATA |
-		windows.FILE_APPEND_DATA |
-		windows.FILE_WRITE_ATTRIBUTES |
-		windows.FILE_WRITE_EA |
-		0x40, // FILE_DELETE_CHILD
-)
-
-// checkStatusDirOwner validates ownership and write access through a handle
-// opened beneath root. Path-based ACL inspection would recreate the ancestor
-// swap race that Root is intended to close.
-func checkStatusDirOwner(root *os.Root, _ os.FileInfo) (returnErr error) {
-	directory, err := root.Open(".")
-	if err != nil {
-		return fmt.Errorf("open status directory for access validation: %w", err)
-	}
-	defer func() {
-		if err := directory.Close(); err != nil {
-			returnErr = errors.Join(returnErr, fmt.Errorf("close status directory access handle: %w", err))
-		}
-	}()
-
-	raw, err := directory.SyscallConn()
-	if err != nil {
-		return fmt.Errorf("access status directory handle: %w", err)
-	}
-	var descriptor *windows.SECURITY_DESCRIPTOR
-	var queryErr error
-	if err := raw.Control(func(handle uintptr) {
-		descriptor, queryErr = windows.GetSecurityInfo(
-			windows.Handle(handle),
-			windows.SE_FILE_OBJECT,
-			windows.OWNER_SECURITY_INFORMATION|windows.DACL_SECURITY_INFORMATION,
-		)
-	}); err != nil {
-		return fmt.Errorf("inspect status directory access: %w", err)
-	}
-	if queryErr != nil {
-		return fmt.Errorf("inspect status directory owner and DACL: %w", queryErr)
-	}
-	if descriptor == nil {
-		return fmt.Errorf("status directory security descriptor is unavailable")
-	}
-
-	token := windows.GetCurrentProcessToken()
-	user, err := token.GetTokenUser()
-	if err != nil {
-		return fmt.Errorf("resolve current Windows user: %w", err)
-	}
-	tokenOwner, err := currentWindowsTokenOwner(token)
-	if err != nil {
-		return fmt.Errorf("resolve current Windows token owner: %w", err)
-	}
-	owner, _, err := descriptor.Owner()
-	if err != nil {
-		return fmt.Errorf("read status directory owner: %w", err)
-	}
-	if owner == nil || (!owner.Equals(user.User.Sid) && !owner.Equals(tokenOwner)) {
-		return fmt.Errorf("status directory is not owned by the current Windows token")
-	}
-
-	dacl, _, err := descriptor.DACL()
-	if err != nil {
-		return fmt.Errorf("read status directory DACL: %w", err)
-	}
-	if dacl == nil {
-		return fmt.Errorf("status directory has an unrestricted Windows DACL")
-	}
-	for index := uint16(0); index < dacl.AceCount; index++ {
-		var ace *windows.ACCESS_ALLOWED_ACE
-		if err := windows.GetAce(dacl, uint32(index), &ace); err != nil {
-			return fmt.Errorf("read status directory DACL entry %d: %w", index, err)
-		}
-		switch ace.Header.AceType {
-		case windows.ACCESS_DENIED_ACE_TYPE:
-			continue
-		case windows.ACCESS_ALLOWED_ACE_TYPE:
-		default:
-			return fmt.Errorf("status directory DACL entry %d has unsupported type %d", index, ace.Header.AceType)
-		}
-		if ace.Mask&statusDirectoryWriteAccess == 0 {
-			continue
-		}
-		trustee := (*windows.SID)(unsafe.Pointer(&ace.SidStart))
-		if !allowedStatusDirectoryTrustee(trustee, user.User.Sid) {
-			return fmt.Errorf("status directory DACL grants write access to unexpected trustee %s", trustee.String())
-		}
-	}
-	return nil
-}
-
-type statusDirectoryTokenOwner struct {
-	owner *windows.SID
-}
-
-func currentWindowsTokenOwner(token windows.Token) (*windows.SID, error) {
-	var size uint32
-	err := windows.GetTokenInformation(token, windows.TokenOwner, nil, 0, &size)
-	if err != windows.ERROR_INSUFFICIENT_BUFFER {
-		return nil, err
-	}
-	buffer := make([]byte, size)
-	if err := windows.GetTokenInformation(token, windows.TokenOwner, &buffer[0], size, &size); err != nil {
-		return nil, err
-	}
-	owner := (*statusDirectoryTokenOwner)(unsafe.Pointer(&buffer[0])).owner
-	if owner == nil {
-		return nil, errors.New("windows access token has no default owner")
-	}
-	return owner.Copy()
-}
-
-func allowedStatusDirectoryTrustee(trustee, user *windows.SID) bool {
-	return trustee != nil && (trustee.Equals(user) ||
-		trustee.IsWellKnown(windows.WinLocalSystemSid) ||
-		trustee.IsWellKnown(windows.WinBuiltinAdministratorsSid) ||
-		trustee.IsWellKnown(windows.WinCreatorOwnerSid) ||
-		trustee.IsWellKnown(windows.WinCreatorOwnerRightsSid))
-}

internal/daemon/status_dir_owner_windows_test.go

@@ -1,97 +0,0 @@
-//go:build windows
-
-package daemon
-
-import (
-	"fmt"
-	"os"
-	"runtime"
-	"strings"
-	"testing"
-
-	"golang.org/x/sys/windows"
-)
-
-func secureStatusTestDirPlatform(t *testing.T, dir string) {
-	t.Helper()
-	user, err := windows.GetCurrentProcessToken().GetTokenUser()
-	if err != nil {
-		t.Fatal(err)
-	}
-	descriptor, err := windows.SecurityDescriptorFromString(
-		fmt.Sprintf("O:%sD:P(A;OICI;GA;;;%s)(A;OICI;GA;;;SY)", user.User.Sid.String(), user.User.Sid.String()),
-	)
-	if err != nil {
-		t.Fatal(err)
-	}
-	dacl, _, err := descriptor.DACL()
-	if err != nil {
-		t.Fatal(err)
-	}
-	if err := windows.SetNamedSecurityInfo(
-		dir,
-		windows.SE_FILE_OBJECT,
-		windows.DACL_SECURITY_INFORMATION|windows.PROTECTED_DACL_SECURITY_INFORMATION,
-		nil,
-		nil,
-		dacl,
-		nil,
-	); err != nil {
-		t.Fatal(err)
-	}
-}
-
-func broadenStatusTestDirPlatform(t *testing.T, dir string) {
-	t.Helper()
-	worldSID, err := windows.CreateWellKnownSid(windows.WinWorldSid)
-	if err != nil {
-		t.Fatal(err)
-	}
-	var pinner runtime.Pinner
-	pinner.Pin(worldSID)
-	defer pinner.Unpin()
-	broadDACL, err := windows.ACLFromEntries([]windows.EXPLICIT_ACCESS{{
-		AccessPermissions: windows.GENERIC_ALL,
-		AccessMode:        windows.GRANT_ACCESS,
-		Inheritance:       windows.SUB_CONTAINERS_AND_OBJECTS_INHERIT,
-		Trustee: windows.TRUSTEE{
-			TrusteeForm:  windows.TRUSTEE_IS_SID,
-			TrusteeType:  windows.TRUSTEE_IS_WELL_KNOWN_GROUP,
-			TrusteeValue: windows.TrusteeValueFromSID(worldSID),
-		},
-	}}, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if err := windows.SetNamedSecurityInfo(
-		dir,
-		windows.SE_FILE_OBJECT,
-		windows.DACL_SECURITY_INFORMATION|windows.PROTECTED_DACL_SECURITY_INFORMATION,
-		nil,
-		nil,
-		broadDACL,
-		nil,
-	); err != nil {
-		t.Fatal(err)
-	}
-}
-
-func TestCheckStatusDirOwnerRejectsBroadDACL(t *testing.T) {
-	dir := t.TempDir()
-	secureStatusTestDirPlatform(t, dir)
-	broadenStatusTestDirPlatform(t, dir)
-
-	root, err := os.OpenRoot(dir)
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer root.Close()
-	info, err := root.Stat(".")
-	if err != nil {
-		t.Fatal(err)
-	}
-	err = checkStatusDirOwner(root, info)
-	if err == nil || !strings.Contains(err.Error(), "unexpected trustee") {
-		t.Fatalf("checkStatusDirOwner error = %v, want broad DACL rejection", err)
-	}
-}

internal/daemon/status_file.go

@@ -1,169 +0,0 @@
-package daemon
-
-import (
-	"crypto/rand"
-	"encoding/hex"
-	"errors"
-	"fmt"
-	"os"
-	"path/filepath"
-	"runtime"
-
-	"github.com/Gitlawb/zero/internal/fsutil"
-)
-
-const (
-	statusTempPrefix  = ".daemon-status-"
-	statusTempPattern = statusTempPrefix + "*"
-)
-
-func openStatusRoot(path string) (*os.Root, error) {
-	root, err := os.OpenRoot(filepath.Dir(path))
-	if err != nil {
-		return nil, fmt.Errorf("open status directory: %w", err)
-	}
-	if err := validateStatusRoot(root); err != nil {
-		_ = root.Close()
-		return nil, err
-	}
-	return root, nil
-}
-
-// writeStatusFileAtomicallyRoot publishes through a caller-owned, already
-// bound directory root. The returned boolean crosses the commit boundary: once
-// true, err is a durability/cleanup warning and the complete document is live.
-func writeStatusFileAtomicallyRoot(
-	root *os.Root,
-	statusName string,
-	data []byte,
-	perm os.FileMode,
-	beforeReplace func(),
-	replace func(root *os.Root, src, dst string) error,
-	syncParent func(root *os.Root) error,
-) (committed bool, returnErr error) {
-	if err := validateStatusRoot(root); err != nil {
-		return false, err
-	}
-
-	temp, tempName, err := createStatusTemp(root, perm)
-	if err != nil {
-		return false, err
-	}
-	closed := false
-	defer func() {
-		if !closed {
-			if err := temp.Close(); err != nil {
-				returnErr = errors.Join(returnErr, fmt.Errorf("close temporary status file during cleanup: %w", err))
-			}
-			closed = true
-		}
-		if err := root.Remove(tempName); err != nil && !errors.Is(err, os.ErrNotExist) {
-			returnErr = errors.Join(returnErr, fmt.Errorf("remove temporary status file: %w", err))
-		}
-	}()
-
-	if err := temp.Chmod(perm); err != nil {
-		return false, fmt.Errorf("set temporary status file permissions: %w", err)
-	}
-	if _, err := temp.Write(data); err != nil {
-		return false, fmt.Errorf("write temporary status file: %w", err)
-	}
-	if err := temp.Sync(); err != nil {
-		return false, fmt.Errorf("sync temporary status file: %w", err)
-	}
-	closeErr := temp.Close()
-	closed = true
-	if closeErr != nil {
-		return false, fmt.Errorf("close temporary status file: %w", closeErr)
-	}
-	if beforeReplace != nil {
-		beforeReplace()
-	}
-	if err := prepareStatusReplacement(root, tempName, statusName); err != nil {
-		return false, fmt.Errorf("prepare status replacement: %w", err)
-	}
-
-	rename := root.Rename
-	if replace != nil {
-		rename = func(src, dst string) error { return replace(root, src, dst) }
-	}
-	// On Windows an existing reader that omitted FILE_SHARE_DELETE can block
-	// this replacement even though an in-place write would succeed. Keep the
-	// atomic publication boundary: RenameWithRetry bounds transient sharing
-	// failures to ten short attempts, and a persistent failure leaves the old
-	// status document intact instead of exposing a partially written one.
-	var committedWarning error
-	if err := fsutil.RenameWithRetry(tempName, statusName, rename); err != nil {
-		var committedReplacement *fsutil.CommittedReplacementCleanupError
-		if !errors.As(err, &committedReplacement) {
-			return false, fmt.Errorf("replace status file: %w", err)
-		}
-		committedWarning = fmt.Errorf("clean up replaced status file: %w", err)
-	}
-	committed = true
-	if syncParent == nil {
-		syncParent = syncStatusRoot
-	}
-	if err := syncParent(root); err != nil {
-		committedWarning = errors.Join(committedWarning, fmt.Errorf("sync status directory: %w", err))
-	}
-	if committedWarning != nil {
-		return committed, committedWarning
-	}
-	return committed, nil
-}
-
-func validateStatusRoot(root *os.Root) error {
-	info, err := root.Stat(".")
-	if err != nil {
-		return fmt.Errorf("inspect status directory: %w", err)
-	}
-	if !info.IsDir() {
-		return fmt.Errorf("status directory is not a directory")
-	}
-	if runtime.GOOS != "windows" && info.Mode().Perm()&0o022 != 0 {
-		return fmt.Errorf("status directory permissions are %04o, want no group/other write access", info.Mode().Perm())
-	}
-	if err := checkStatusDirOwner(root, info); err != nil {
-		return err
-	}
-	return nil
-}
-
-func createStatusTemp(root *os.Root, perm os.FileMode) (*os.File, string, error) {
-	for range 100 {
-		var suffix [16]byte
-		if _, err := rand.Read(suffix[:]); err != nil {
-			return nil, "", fmt.Errorf("generate temporary status file name: %w", err)
-		}
-		name := statusTempPrefix + hex.EncodeToString(suffix[:])
-		file, err := root.OpenFile(name, os.O_WRONLY|os.O_CREATE|os.O_EXCL, perm)
-		if err == nil {
-			return file, name, nil
-		}
-		if errors.Is(err, os.ErrExist) {
-			continue
-		}
-		return nil, "", fmt.Errorf("create temporary status file: %w", err)
-	}
-	return nil, "", fmt.Errorf("create temporary status file: exhausted unique names")
-}
-
-// syncStatusRoot makes the replacement directory entry durable through the
-// same bound root used for creation and replacement. Windows directory sync is
-// best-effort because Go cannot fsync a directory there.
-func syncStatusRoot(root *os.Root) error {
-	if runtime.GOOS == "windows" {
-		return nil
-	}
-	directory, err := root.Open(".")
-	if err != nil {
-		return err
-	}
-	syncErr := directory.Sync()
-	closeErr := directory.Close()
-	if syncErr != nil {
-		return syncErr
-	}
-	return closeErr
-}

internal/daemon/status_file_test.go

@@ -1,476 +0,0 @@
-package daemon
-
-import (
-	"encoding/json"
-	"errors"
-	"os"
-	"path/filepath"
-	"runtime"
-	"strings"
-	"testing"
-	"time"
-
-	"github.com/Gitlawb/zero/internal/fsutil"
-	"github.com/Gitlawb/zero/internal/privatedir"
-)
-
-func TestWriteStatusFilePreservesPreviousDocumentWhenReplaceFails(t *testing.T) {
-	dir := t.TempDir()
-	secureStatusTestDir(t, dir)
-	path := filepath.Join(dir, "daemon.status")
-	previous := []byte(`{"pid":7,"socket":"old.sock","version":1,"startedAt":"2026-08-01T00:00:00Z"}`)
-	if err := os.WriteFile(path, previous, 0o600); err != nil {
-		t.Fatal(err)
-	}
-
-	replaceErr := errors.New("injected replacement failure")
-	server := &Server{
-		startedAt: time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC),
-		opts: ServerOptions{
-			Paths:   Paths{Status: path},
-			Version: 2,
-			replaceStatusFile: func(root *os.Root, src, dst string) error {
-				staged, err := root.ReadFile(src)
-				if err != nil {
-					t.Fatalf("read staged status: %v", err)
-				}
-				var decoded StatusFile
-				if err := json.Unmarshal(staged, &decoded); err != nil {
-					t.Fatalf("staged status is incomplete JSON: %v", err)
-				}
-				current, err := root.ReadFile(dst)
-				if err != nil {
-					t.Fatalf("read previous status at commit boundary: %v", err)
-				}
-				if string(current) != string(previous) {
-					t.Fatalf("previous status changed before commit: %q", current)
-				}
-				return replaceErr
-			},
-		},
-	}
-
-	err := server.writeStatusFile()
-	if !errors.Is(err, replaceErr) {
-		t.Fatalf("writeStatusFile error = %v, want injected replacement failure", err)
-	}
-	current, err := os.ReadFile(path)
-	if err != nil {
-		t.Fatalf("read preserved status: %v", err)
-	}
-	if string(current) != string(previous) {
-		t.Fatalf("status after failed publication = %q, want previous document", current)
-	}
-	assertNoStatusTemps(t, dir)
-}
-
-func TestWriteStatusFilePublishesCompleteRestrictedDocument(t *testing.T) {
-	dir := t.TempDir()
-	secureStatusTestDir(t, dir)
-	path := filepath.Join(dir, "daemon.status")
-	if err := os.WriteFile(path, []byte(`{"pid":7}`), 0o644); err != nil {
-		t.Fatal(err)
-	}
-
-	startedAt := time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC)
-	parentSynced := false
-	server := &Server{
-		startedAt: startedAt,
-		opts: ServerOptions{
-			Paths:   Paths{Socket: filepath.Join(dir, "daemon.sock"), Status: path},
-			Version: 3,
-			syncStatusParent: func(root *os.Root) error {
-				if _, err := root.Stat("."); err != nil {
-					t.Fatalf("stat bound status parent: %v", err)
-				}
-				parentSynced = true
-				return nil
-			},
-		},
-	}
-
-	if err := server.writeStatusFile(); err != nil {
-		t.Fatalf("writeStatusFile: %v", err)
-	}
-	data, err := os.ReadFile(path)
-	if err != nil {
-		t.Fatal(err)
-	}
-	var status StatusFile
-	if err := json.Unmarshal(data, &status); err != nil {
-		t.Fatalf("published status is invalid JSON: %v", err)
-	}
-	if status.PID != os.Getpid() || status.Socket != server.opts.Paths.Socket || status.Version != 3 || !status.StartedAt.Equal(startedAt) {
-		t.Fatalf("published status = %+v", status)
-	}
-	if !parentSynced {
-		t.Fatal("status parent directory was not synced")
-	}
-	if runtime.GOOS != "windows" {
-		info, err := os.Stat(path)
-		if err != nil {
-			t.Fatal(err)
-		}
-		if got := info.Mode().Perm(); got != 0o600 {
-			t.Fatalf("status mode = %04o, want 0600", got)
-		}
-	}
-	assertNoStatusTemps(t, dir)
-}
-
-func TestWriteStatusFileReaderSeesCompleteDocumentsDuringPublication(t *testing.T) {
-	dir := t.TempDir()
-	secureStatusTestDir(t, dir)
-	path := filepath.Join(dir, "daemon.status")
-	previous := StatusFile{
-		PID:       7,
-		Socket:    filepath.Join(dir, "old.sock"),
-		Version:   1,
-		StartedAt: time.Date(2026, 8, 1, 0, 0, 0, 0, time.UTC),
-	}
-	previousData, err := json.Marshal(previous)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if err := os.WriteFile(path, previousData, 0o600); err != nil {
-		t.Fatal(err)
-	}
-
-	replacementReady := make(chan struct{})
-	publish := make(chan struct{})
-	writeDone := make(chan error, 1)
-	server := &Server{
-		startedAt: time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC),
-		opts: ServerOptions{
-			Paths:   Paths{Socket: filepath.Join(dir, "new.sock"), Status: path},
-			Version: 2,
-			replaceStatusFile: func(root *os.Root, src, dst string) error {
-				close(replacementReady)
-				<-publish
-				return fsutil.RenameWithRetry(src, dst, root.Rename)
-			},
-		},
-	}
-	go func() {
-		writeDone <- server.writeStatusFile()
-	}()
-
-	<-replacementReady
-	for range 100 {
-		status := readStatusDocument(t, path)
-		if status != previous {
-			t.Fatalf("status before commit = %+v, want previous document %+v", status, previous)
-		}
-	}
-	close(publish)
-	if err := <-writeDone; err != nil {
-		t.Fatalf("writeStatusFile: %v", err)
-	}
-
-	status := readStatusDocument(t, path)
-	if status.PID != os.Getpid() || status.Socket != server.opts.Paths.Socket || status.Version != 2 || !status.StartedAt.Equal(server.startedAt) {
-		t.Fatalf("status after commit = %+v", status)
-	}
-	assertNoStatusTemps(t, dir)
-}
-
-func TestWriteStatusFileContinuesAfterDirectorySyncWarning(t *testing.T) {
-	dir := t.TempDir()
-	secureStatusTestDir(t, dir)
-	path := filepath.Join(dir, "daemon.status")
-	if err := os.WriteFile(path, []byte(`{"pid":7}`), 0o600); err != nil {
-		t.Fatal(err)
-	}
-
-	syncErr := errors.New("injected directory sync failure")
-	var logs []string
-	server := &Server{
-		startedAt: time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC),
-		opts: ServerOptions{
-			Paths:            Paths{Socket: filepath.Join(dir, "daemon.sock"), Status: path},
-			Version:          4,
-			Log:              func(message string) { logs = append(logs, message) },
-			syncStatusParent: func(*os.Root) error { return syncErr },
-		},
-	}
-
-	if err := server.writeStatusFile(); err != nil {
-		t.Fatalf("writeStatusFile returned a post-commit warning as failure: %v", err)
-	}
-	status := readStatusDocument(t, path)
-	if status.Version != 4 {
-		t.Fatalf("published status = %+v, want version 4", status)
-	}
-	if len(logs) != 1 || !strings.Contains(logs[0], syncErr.Error()) {
-		t.Fatalf("logs = %q, want directory sync warning", logs)
-	}
-	assertNoStatusTemps(t, dir)
-}
-
-func TestWriteStatusFileContinuesAfterCommittedReplacementWarning(t *testing.T) {
-	dir := t.TempDir()
-	secureStatusTestDir(t, dir)
-	path := filepath.Join(dir, "daemon.status")
-	if err := os.WriteFile(path, []byte(`{"pid":7}`), 0o600); err != nil {
-		t.Fatal(err)
-	}
-
-	cleanupErr := errors.New("injected backup cleanup failure")
-	parentSynced := false
-	var logs []string
-	server := &Server{
-		startedAt: time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC),
-		opts: ServerOptions{
-			Paths:   Paths{Socket: filepath.Join(dir, "daemon.sock"), Status: path},
-			Version: 5,
-			Log:     func(message string) { logs = append(logs, message) },
-			replaceStatusFile: func(root *os.Root, src, dst string) error {
-				if err := fsutil.RenameWithRetry(src, dst, root.Rename); err != nil {
-					return err
-				}
-				return &fsutil.CommittedReplacementCleanupError{
-					BackupPath: filepath.Join(dir, ".zero-replace-backup"),
-					Cause:      cleanupErr,
-				}
-			},
-			syncStatusParent: func(*os.Root) error {
-				parentSynced = true
-				return nil
-			},
-		},
-	}
-
-	if err := server.writeStatusFile(); err != nil {
-		t.Fatalf("writeStatusFile returned a post-commit warning as failure: %v", err)
-	}
-	if !parentSynced {
-		t.Fatal("status directory was not synced after committed replacement warning")
-	}
-	status := readStatusDocument(t, path)
-	if status.Version != 5 {
-		t.Fatalf("published status = %+v, want version 5", status)
-	}
-	if len(logs) != 1 || !strings.Contains(logs[0], cleanupErr.Error()) {
-		t.Fatalf("logs = %q, want committed cleanup warning", logs)
-	}
-	assertNoStatusTemps(t, dir)
-}
-
-func TestWriteStatusFileContinuesAfterCommittedTempCleanupWarning(t *testing.T) {
-	dir := t.TempDir()
-	secureStatusTestDir(t, dir)
-	path := filepath.Join(dir, "daemon.status")
-	if err := os.WriteFile(path, []byte(`{"pid":7}`), 0o600); err != nil {
-		t.Fatal(err)
-	}
-
-	var tempName string
-	var logs []string
-	server := &Server{
-		startedAt: time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC),
-		opts: ServerOptions{
-			Paths:   Paths{Socket: filepath.Join(dir, "daemon.sock"), Status: path},
-			Version: 6,
-			Log:     func(message string) { logs = append(logs, message) },
-			replaceStatusFile: func(root *os.Root, src, dst string) error {
-				if err := fsutil.RenameWithRetry(src, dst, root.Rename); err != nil {
-					return err
-				}
-				tempName = src
-				if err := root.Mkdir(src, 0o700); err != nil {
-					t.Fatalf("recreate staged path as directory: %v", err)
-				}
-				keep, err := root.OpenFile(filepath.Join(src, "keep"), os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0o600)
-				if err != nil {
-					t.Fatalf("make staged directory non-empty: %v", err)
-				}
-				if err := keep.Close(); err != nil {
-					t.Fatalf("close staged directory marker: %v", err)
-				}
-				return nil
-			},
-		},
-	}
-
-	if err := server.writeStatusFile(); err != nil {
-		t.Fatalf("writeStatusFile returned a post-commit warning as failure: %v", err)
-	}
-	status := readStatusDocument(t, path)
-	if status.Version != 6 {
-		t.Fatalf("published status = %+v, want version 6", status)
-	}
-	if len(logs) != 1 || !strings.Contains(logs[0], "remove temporary status file") {
-		t.Fatalf("logs = %q, want temporary cleanup warning", logs)
-	}
-	if err := os.Remove(filepath.Join(dir, tempName, "keep")); err != nil {
-		t.Fatal(err)
-	}
-	if err := os.Remove(filepath.Join(dir, tempName)); err != nil {
-		t.Fatal(err)
-	}
-	assertNoStatusTemps(t, dir)
-}
-
-func TestWriteStatusFileBindsDirectoryDuringAncestorSwap(t *testing.T) {
-	parent := t.TempDir()
-	dir := filepath.Join(parent, "live")
-	movedDir := filepath.Join(parent, "moved")
-	if err := os.Mkdir(dir, 0o700); err != nil {
-		t.Fatal(err)
-	}
-	secureStatusTestDir(t, dir)
-	path := filepath.Join(dir, "daemon.status")
-	if err := os.WriteFile(path, []byte(`{"pid":7}`), 0o600); err != nil {
-		t.Fatal(err)
-	}
-
-	substitute := []byte(`{"pid":999,"socket":"substitute"}`)
-	var swapErr error
-	server := &Server{
-		startedAt: time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC),
-		opts: ServerOptions{
-			Paths:   Paths{Socket: filepath.Join(dir, "daemon.sock"), Status: path},
-			Version: 6,
-			beforeStatusReplace: func() {
-				swapErr = os.Rename(dir, movedDir)
-				if swapErr != nil {
-					if runtime.GOOS == "windows" {
-						return
-					}
-					t.Fatalf("move bound status directory: %v", swapErr)
-				}
-				if err := os.Mkdir(dir, 0o700); err != nil {
-					t.Fatalf("create substitute status directory: %v", err)
-				}
-				if err := os.WriteFile(path, substitute, 0o600); err != nil {
-					t.Fatalf("write substitute status: %v", err)
-				}
-			},
-		},
-	}
-
-	if err := server.writeStatusFile(); err != nil {
-		t.Fatalf("writeStatusFile: %v", err)
-	}
-	if swapErr != nil {
-		if runtime.GOOS != "windows" {
-			t.Fatalf("unexpected directory-swap error: %v", swapErr)
-		}
-		status := readStatusDocument(t, path)
-		if status.Version != 6 {
-			t.Fatalf("status after blocked swap = %+v, want version 6", status)
-		}
-		if _, err := os.Lstat(movedDir); !os.IsNotExist(err) {
-			t.Fatalf("moved directory exists after blocked Windows swap: %v", err)
-		}
-		assertNoStatusTemps(t, dir)
-		return
-	}
-	if got, err := os.ReadFile(path); err != nil {
-		t.Fatal(err)
-	} else if string(got) != string(substitute) {
-		t.Fatalf("substitute destination changed: %q", got)
-	}
-	status := readStatusDocument(t, filepath.Join(movedDir, "daemon.status"))
-	if status.Version != 6 {
-		t.Fatalf("bound status = %+v, want version 6", status)
-	}
-	assertNoStatusTemps(t, dir)
-	assertNoStatusTemps(t, movedDir)
-}
-
-func TestWriteStatusFileAllowsReadOnlyCustomStatusDirectory(t *testing.T) {
-	if runtime.GOOS == "windows" {
-		t.Skip("Windows directory access is governed by DACLs, not Unix mode bits")
-	}
-	dir := t.TempDir()
-	if err := os.Chmod(dir, 0o755); err != nil {
-		t.Fatal(err)
-	}
-	path := filepath.Join(dir, "daemon.status")
-
-	server := &Server{
-		startedAt: time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC),
-		opts: ServerOptions{
-			Paths:   Paths{Status: path},
-			Version: 6,
-		},
-	}
-	err := server.writeStatusFile()
-	if err != nil {
-		t.Fatalf("writeStatusFile in 0755 directory: %v", err)
-	}
-	if _, err := os.Lstat(path); err != nil {
-		t.Fatalf("status file not created in read-only custom directory: %v", err)
-	}
-	assertNoStatusTemps(t, dir)
-}
-
-func TestWriteStatusFileRejectsWritableStatusDirectory(t *testing.T) {
-	if runtime.GOOS == "windows" {
-		t.Skip("Windows directory access is governed by DACLs, not Unix mode bits")
-	}
-	dir := t.TempDir()
-	if err := os.Chmod(dir, 0o777); err != nil {
-		t.Fatal(err)
-	}
-	path := filepath.Join(dir, "daemon.status")
-	server := &Server{
-		startedAt: time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC),
-		opts:      ServerOptions{Paths: Paths{Status: path}, Version: 6},
-	}
-	err := server.writeStatusFile()
-	if err == nil || !strings.Contains(err.Error(), "no group/other write access") {
-		t.Fatalf("writeStatusFile error = %v, want writable-directory rejection", err)
-	}
-	if _, err := os.Lstat(path); !os.IsNotExist(err) {
-		t.Fatalf("status file created in writable directory: %v", err)
-	}
-	assertNoStatusTemps(t, dir)
-}
-
-func TestPrivateDirHardensBroadCurrentUserStatusDirectory(t *testing.T) {
-	dir := t.TempDir()
-	broadenStatusTestDirPlatform(t, dir)
-	if err := privatedir.Ensure(dir); err != nil {
-		t.Fatalf("privatedir.Ensure: %v", err)
-	}
-	root, err := os.OpenRoot(dir)
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer root.Close()
-
-	if err := validateStatusRoot(root); err != nil {
-		t.Fatalf("validate hardened status root: %v", err)
-	}
-}
-
-func readStatusDocument(t *testing.T, path string) StatusFile {
-	t.Helper()
-	data, err := os.ReadFile(path)
-	if err != nil {
-		t.Fatalf("read status: %v", err)
-	}
-	var status StatusFile
-	if err := json.Unmarshal(data, &status); err != nil {
-		t.Fatalf("status is incomplete JSON: %v (content %q)", err, data)
-	}
-	return status
-}
-
-func assertNoStatusTemps(t *testing.T, dir string) {
-	t.Helper()
-	matches, err := filepath.Glob(filepath.Join(dir, statusTempPattern))
-	if err != nil {
-		t.Fatal(err)
-	}
-	if len(matches) != 0 {
-		t.Fatalf("temporary status files remain: %v", matches)
-	}
-}
-
-func secureStatusTestDir(t *testing.T, dir string) {
-	t.Helper()
-	secureStatusTestDirPlatform(t, dir)
-}

internal/daemon/status_file_windows_test.go

@@ -1,63 +0,0 @@
-//go:build windows
-
-package daemon
-
-import (
-	"os"
-	"path/filepath"
-	"strings"
-	"testing"
-	"time"
-
-	"golang.org/x/sys/windows"
-)
-
-func TestWriteStatusFilePreservesExistingProtectedDACL(t *testing.T) {
-	dir := t.TempDir()
-	secureStatusTestDir(t, dir)
-	path := filepath.Join(dir, "daemon.status")
-	if err := os.WriteFile(path, []byte(`{"pid":7}`), 0o600); err != nil {
-		t.Fatal(err)
-	}
-	restricted, err := windows.SecurityDescriptorFromString("D:P(A;;FA;;;OW)")
-	if err != nil {
-		t.Skipf("cannot build restrictive DACL: %v", err)
-	}
-	dacl, _, err := restricted.DACL()
-	if err != nil {
-		t.Skipf("cannot read restrictive DACL: %v", err)
-	}
-	if err := windows.SetNamedSecurityInfo(path, windows.SE_FILE_OBJECT,
-		windows.DACL_SECURITY_INFORMATION|windows.PROTECTED_DACL_SECURITY_INFORMATION,
-		nil, nil, dacl, nil); err != nil {
-		t.Skipf("cannot apply restrictive DACL: %v", err)
-	}
-	want := statusDACL(t, path)
-
-	server := &Server{
-		startedAt: time.Date(2026, 8, 30, 18, 0, 0, 0, time.UTC),
-		opts: ServerOptions{
-			Paths:   Paths{Socket: filepath.Join(dir, "daemon.sock"), Status: path},
-			Version: 2,
-		},
-	}
-	if err := server.writeStatusFile(); err != nil {
-		t.Fatalf("writeStatusFile: %v", err)
-	}
-	if got := statusDACL(t, path); got != want {
-		t.Fatalf("status DACL after replacement = %q, want %q", got, want)
-	}
-}
-
-func statusDACL(t *testing.T, path string) string {
-	t.Helper()
-	descriptor, err := windows.GetNamedSecurityInfo(path, windows.SE_FILE_OBJECT, windows.DACL_SECURITY_INFORMATION)
-	if err != nil {
-		t.Skipf("cannot read status DACL: %v", err)
-	}
-	text := descriptor.String()
-	if index := strings.Index(text, "D:"); index >= 0 {
-		return text[index:]
-	}
-	return text
-}

internal/daemon/status_replace_other.go

@@ -1,7 +0,0 @@
-//go:build !windows
-
-package daemon
-
-import "os"
-
-func prepareStatusReplacement(*os.Root, string, string) error { return nil }

internal/daemon/status_replace_windows.go

@@ -1,136 +0,0 @@
-//go:build windows
-
-package daemon
-
-import (
-	"errors"
-	"fmt"
-	"os"
-	"path/filepath"
-	"unsafe"
-
-	"golang.org/x/sys/windows"
-)
-
-// prepareStatusReplacement copies the existing status document's DACL to the
-// complete staging file before Root.Rename replaces it. Both files are opened
-// relative to the already-bound Root directory handle, so preserving Windows
-// security metadata does not reintroduce a pathname/ancestor-swap boundary.
-func prepareStatusReplacement(root *os.Root, src, dst string) (returnErr error) {
-	if filepath.Base(src) != src || filepath.Base(dst) != dst {
-		return fmt.Errorf("status replacement names must be root-relative base names")
-	}
-	directory, err := root.Open(".")
-	if err != nil {
-		return fmt.Errorf("open bound status directory for DACL preservation: %w", err)
-	}
-	defer func() {
-		if err := directory.Close(); err != nil {
-			returnErr = errors.Join(returnErr, fmt.Errorf("close bound status directory for DACL preservation: %w", err))
-		}
-	}()
-
-	raw, err := directory.SyscallConn()
-	if err != nil {
-		return fmt.Errorf("access bound status directory handle: %w", err)
-	}
-	var destination, source windows.Handle
-	var openErr error
-	if err := raw.Control(func(rootHandle uintptr) {
-		destination, openErr = openStatusSecurityHandle(windows.Handle(rootHandle), dst, windows.READ_CONTROL|windows.FILE_READ_ATTRIBUTES)
-		if isMissingStatusObject(openErr) {
-			openErr = nil // no destination descriptor exists to preserve
-			return
-		}
-		if openErr != nil {
-			return
-		}
-		source, openErr = openStatusSecurityHandle(windows.Handle(rootHandle), src, windows.READ_CONTROL|windows.WRITE_DAC|windows.FILE_READ_ATTRIBUTES)
-	}); err != nil {
-		return fmt.Errorf("open status files through bound directory: %w", err)
-	}
-	if destination != 0 {
-		defer windows.CloseHandle(destination)
-	}
-	if source != 0 {
-		defer windows.CloseHandle(source)
-	}
-	if openErr != nil {
-		return fmt.Errorf("open status files for DACL preservation: %w", openErr)
-	}
-	if destination == 0 {
-		return nil
-	}
-
-	descriptor, err := windows.GetSecurityInfo(destination, windows.SE_FILE_OBJECT, windows.DACL_SECURITY_INFORMATION)
-	if err != nil {
-		return fmt.Errorf("read existing status DACL: %w", err)
-	}
-	dacl, _, err := descriptor.DACL()
-	if err != nil {
-		return fmt.Errorf("decode existing status DACL: %w", err)
-	}
-	if dacl == nil {
-		return fmt.Errorf("existing status file has an unrestricted Windows DACL")
-	}
-	control, _, err := descriptor.Control()
-	if err != nil {
-		return fmt.Errorf("read existing status DACL control: %w", err)
-	}
-	securityInfo := windows.SECURITY_INFORMATION(windows.DACL_SECURITY_INFORMATION)
-	if control&windows.SE_DACL_PROTECTED != 0 {
-		securityInfo |= windows.SECURITY_INFORMATION(windows.PROTECTED_DACL_SECURITY_INFORMATION)
-	} else {
-		securityInfo |= windows.SECURITY_INFORMATION(windows.UNPROTECTED_DACL_SECURITY_INFORMATION)
-	}
-	if err := windows.SetSecurityInfo(source, windows.SE_FILE_OBJECT, securityInfo, nil, nil, dacl, nil); err != nil {
-		return fmt.Errorf("preserve existing status DACL on replacement: %w", err)
-	}
-	return nil
-}
-
-func openStatusSecurityHandle(root windows.Handle, name string, access uint32) (windows.Handle, error) {
-	objectName, err := windows.NewNTUnicodeString(name)
-	if err != nil {
-		return 0, err
-	}
-	attributes := &windows.OBJECT_ATTRIBUTES{
-		Length:        uint32(unsafe.Sizeof(windows.OBJECT_ATTRIBUTES{})),
-		RootDirectory: root,
-		ObjectName:    objectName,
-		Attributes:    windows.OBJ_CASE_INSENSITIVE | windows.OBJ_DONT_REPARSE,
-	}
-	var handle windows.Handle
-	var status windows.IO_STATUS_BLOCK
-	err = windows.NtCreateFile(
-		&handle,
-		access,
-		attributes,
-		&status,
-		nil,
-		0,
-		windows.FILE_SHARE_READ|windows.FILE_SHARE_WRITE|windows.FILE_SHARE_DELETE,
-		windows.FILE_OPEN,
-		windows.FILE_NON_DIRECTORY_FILE|windows.FILE_OPEN_REPARSE_POINT,
-		0,
-		0,
-	)
-	if err != nil {
-		return 0, err
-	}
-	var info windows.ByHandleFileInformation
-	if err := windows.GetFileInformationByHandle(handle, &info); err != nil {
-		windows.CloseHandle(handle)
-		return 0, err
-	}
-	if info.FileAttributes&windows.FILE_ATTRIBUTE_REPARSE_POINT != 0 {
-		windows.CloseHandle(handle)
-		return 0, fmt.Errorf("refusing status DACL operation on reparse point %q", name)
-	}
-	return handle, nil
-}
-
-func isMissingStatusObject(err error) bool {
-	return errors.Is(err, windows.STATUS_OBJECT_NAME_NOT_FOUND) ||
-		errors.Is(err, windows.STATUS_OBJECT_PATH_NOT_FOUND)
-}

internal/lockutil/lockutil.go

@@ -64,28 +64,6 @@ func TryAcquireFileLockAt(root, path string) (*FileLock, error) {
 	if err != nil {
 		return nil, fmt.Errorf("lockutil: open lock file: %w", err)
 	}
-	return acquireOpenedFileLock(file)
-}
-
-// TryAcquireFileLockRoot attempts to lock name relative to an already-bound
-// directory root. It is intended for lifecycle owners that must not resolve the
-// root pathname again between validation and lock acquisition.
-func TryAcquireFileLockRoot(root *os.Root, name, displayPath string) (*FileLock, error) {
-	if root == nil {
-		return nil, errors.New("lockutil: lock root is nil")
-	}
-	name = filepath.Clean(name)
-	if name == "." || name == ".." || filepath.IsAbs(name) || strings.HasPrefix(name, ".."+string(filepath.Separator)) {
-		return nil, fmt.Errorf("lockutil: lock name %q escapes root", name)
-	}
-	file, err := openLockFileRoot(root, name, displayPath)
-	if err != nil {
-		return nil, fmt.Errorf("lockutil: open rooted lock file: %w", err)
-	}
-	return acquireOpenedFileLock(file)
-}
-
-func acquireOpenedFileLock(file *os.File) (*FileLock, error) {
 	state, contended, err := tryLockFile(file)
 	if err != nil {
 		_ = file.Close()
@@ -104,41 +82,6 @@ func acquireOpenedFileLock(file *os.File) (*FileLock, error) {
 	return lock, nil
 }
 
-func openLockFileRoot(root *os.Root, name, displayPath string) (*os.File, error) {
-	info, err := root.Lstat(name)
-	if errors.Is(err, os.ErrNotExist) {
-		file, createErr := root.OpenFile(name, os.O_CREATE|os.O_EXCL|os.O_RDWR, 0o600)
-		if createErr != nil {
-			return nil, createErr
-		}
-		if err := validateRootLockFile(file); err != nil {
-			return nil, errors.Join(err, file.Close())
-		}
-		return file, nil
-	}
-	if err != nil {
-		return nil, err
-	}
-	if !info.Mode().IsRegular() {
-		return nil, errors.New("refusing non-regular rooted lock file")
-	}
-	file, err := root.OpenFile(name, os.O_RDWR, 0o600)
-	if err != nil {
-		return nil, err
-	}
-	opened, err := file.Stat()
-	if err != nil {
-		return nil, errors.Join(err, file.Close())
-	}
-	if !os.SameFile(info, opened) {
-		return nil, errors.Join(errors.New("rooted lock file changed while opening"), file.Close())
-	}
-	if err := validateRootLockFile(file); err != nil {
-		return nil, errors.Join(err, file.Close())
-	}
-	return file, nil
-}
-
 // WriteMetadata replaces the diagnostic contents of the lock file while the
 // caller holds it. Metadata does not establish ownership; the kernel lock does.
 func (lock *FileLock) WriteMetadata(data []byte) error {

internal/lockutil/lockutil_other.go

@@ -76,20 +76,6 @@ func openLockFileAt(root, relative, displayPath string) (_ *os.File, resultErr e
 	return file, nil
 }
 
-func validateRootLockFile(file *os.File) error {
-	var stat unix.Stat_t
-	if err := unix.Fstat(int(file.Fd()), &stat); err != nil {
-		return fmt.Errorf("inspect rooted lock file: %w", err)
-	}
-	if stat.Mode&unix.S_IFMT != unix.S_IFREG {
-		return errors.New("refusing non-regular rooted lock file")
-	}
-	if stat.Nlink != 1 {
-		return errors.New("refusing multiply-linked rooted lock file")
-	}
-	return nil
-}
-
 func tryLockFile(file *os.File) (platformLockState, bool, error) {
 	err := unix.Flock(int(file.Fd()), unix.LOCK_EX|unix.LOCK_NB)
 	if err == nil {

internal/lockutil/lockutil_windows.go

@@ -73,10 +73,6 @@ func openLockFileAt(root, relative, displayPath string) (_ *os.File, resultErr e
 	return file, nil
 }
 
-func validateRootLockFile(file *os.File) error {
-	return validateWindowsLockHandle(windows.Handle(file.Fd()), false)
-}
-
 func openLockDirectoryAt(parent windows.Handle, name string) (windows.Handle, error) {
 	handle, err := openLockPathAt(
 		parent,

internal/observability/crash.go

@@ -7,50 +7,17 @@
 package observability
 
 import (
-	"crypto/rand"
-	"encoding/hex"
-	"errors"
 	"fmt"
 	"io"
 	"os"
 	"path/filepath"
 	"runtime/debug"
-	"strings"
 	"time"
-
-	"github.com/Gitlawb/zero/internal/privatedir"
 )
 
 // crashExitCode is returned when a top-level panic is recovered.
 const crashExitCode = 1
 
-const crashTempPrefix = ".crash-report-"
-
-// ErrCrashReportCommitted marks an error that happened after a complete crash
-// report was published. Callers may still use the returned path and should
-// surface the error as a cleanup warning rather than as a failed publication.
-var ErrCrashReportCommitted = errors.New("crash report publication committed")
-
-type crashReportCommittedError struct {
-	cause error
-}
-
-func (err *crashReportCommittedError) Error() string {
-	return fmt.Sprintf("%v with warning: %v", ErrCrashReportCommitted, err.cause)
-}
-
-func (err *crashReportCommittedError) Unwrap() []error {
-	return []error{ErrCrashReportCommitted, err.cause}
-}
-
-type crashReportHooks struct {
-	beforePublish   func()
-	write           func(*os.File, []byte) (int, error)
-	link            func(*os.Root, string, string) error
-	renameNoReplace func(*os.Root, string, string) error
-	remove          func(*os.Root, string) error
-}
-
 // FormatCrashReport renders a human-readable crash report.
 func FormatCrashReport(label string, recovered any, stack []byte, ts time.Time) string {
 	return fmt.Sprintf("zero crash report\ntime:  %s\nlabel: %s\npanic: %v\n\nstack:\n%s\n",
@@ -59,189 +26,16 @@ func FormatCrashReport(label string, recovered any, stack []byte, ts time.Time)
 
 // WriteCrashReport writes a crash report file into dir and returns its path.
 func WriteCrashReport(dir, label string, recovered any, stack []byte, ts time.Time) (string, error) {
-	return writeCrashReport(dir, label, recovered, stack, ts, crashReportHooks{})
-}
-
-func writeCrashReport(dir, label string, recovered any, stack []byte, ts time.Time, hooks crashReportHooks) (path string, returnErr error) {
-	absoluteDir, err := filepath.Abs(dir)
-	if err != nil {
-		return "", fmt.Errorf("resolve crash report directory: %w", err)
-	}
-	root, err := openCrashDirectory(dir)
-	if err != nil {
+	if err := os.MkdirAll(dir, 0o755); err != nil {
 		return "", err
 	}
-	committed := false
-	defer func() {
-		if err := root.Close(); err != nil {
-			returnErr = errors.Join(returnErr, fmt.Errorf("close crash report directory: %w", err))
-		}
-		if committed && returnErr != nil && !errors.Is(returnErr, ErrCrashReportCommitted) {
-			returnErr = &crashReportCommittedError{cause: returnErr}
-		}
-		if !committed && returnErr != nil {
-			path = ""
-		}
-	}()
-
-	name := "crash-" + ts.UTC().Format("20060102-150405") + ".log"
-	path = filepath.Join(dir, name)
-	report, tempName, err := createCrashTemp(root)
-	if err != nil {
+	path := filepath.Join(dir, "crash-"+ts.UTC().Format("20060102-150405")+".log")
+	if err := os.WriteFile(path, []byte(FormatCrashReport(label, recovered, stack, ts)), 0o600); err != nil {
 		return "", err
 	}
-	defer func() {
-		if tempName == "" {
-			return
-		}
-		if err := removeCrashTemp(hooks, root, tempName); err != nil && !errors.Is(err, os.ErrNotExist) {
-			returnErr = errors.Join(returnErr, fmt.Errorf("remove temporary crash report: %w", err))
-		}
-	}()
-
-	data := []byte(FormatCrashReport(label, recovered, stack, ts))
-	writeReport := hooks.write
-	if writeReport == nil {
-		writeReport = func(file *os.File, data []byte) (int, error) { return file.Write(data) }
-	}
-	written, err := writeReport(report, data)
-	if err == nil && written != len(data) {
-		err = io.ErrShortWrite
-	}
-	if err != nil {
-		closeErr := report.Close()
-		if closeErr != nil {
-			return "", errors.Join(fmt.Errorf("write crash report: %w", err), fmt.Errorf("close crash report: %w", closeErr))
-		}
-		return "", fmt.Errorf("write crash report: %w", err)
-	}
-	if err := report.Sync(); err != nil {
-		closeErr := report.Close()
-		if closeErr != nil {
-			return "", errors.Join(fmt.Errorf("sync crash report: %w", err), fmt.Errorf("close crash report: %w", closeErr))
-		}
-		return "", fmt.Errorf("sync crash report: %w", err)
-	}
-	if err := report.Close(); err != nil {
-		return "", fmt.Errorf("close crash report: %w", err)
-	}
-	if hooks.beforePublish != nil {
-		hooks.beforePublish()
-	}
-	publishName := name
-	link := root.Link
-	if hooks.link != nil {
-		link = func(oldname, newname string) error { return hooks.link(root, oldname, newname) }
-	}
-	if linkErr := link(tempName, name); linkErr != nil {
-		publishName, err = publishCrashFallback(root, name, tempName, hooks.renameNoReplace)
-		if err != nil {
-			return "", errors.Join(fmt.Errorf("publish crash report with hard link: %w", linkErr), err)
-		}
-		committed = true
-		tempName = ""
-	} else {
-		committed = true
-	}
-	path = filepath.Join(dir, publishName)
-	if !crashPathUsesRoot(root, absoluteDir) {
-		path = ""
-	}
-	if tempName != "" {
-		if err := removeCrashTemp(hooks, root, tempName); err != nil && !errors.Is(err, os.ErrNotExist) {
-			tempName = ""
-			return path, fmt.Errorf("remove temporary crash report: %w", err)
-		}
-		tempName = ""
-	}
 	return path, nil
 }
 
-// publishCrashFallback atomically renames the complete staging file to an
-// unpredictable unused name. The no-replace operation is the collision check;
-// there is no check-then-rename window in which another report can be replaced.
-func publishCrashFallback(root *os.Root, timestampName, tempName string, rename func(*os.Root, string, string) error) (string, error) {
-	if rename == nil {
-		rename = renameNoReplace
-	}
-	base := strings.TrimSuffix(timestampName, filepath.Ext(timestampName))
-	if suffix := strings.TrimPrefix(tempName, crashTempPrefix); suffix != "" && suffix != tempName {
-		candidate := base + "-" + suffix + filepath.Ext(timestampName)
-		if err := rename(root, tempName, candidate); err == nil {
-			return candidate, nil
-		} else if !errors.Is(err, os.ErrExist) {
-			return "", fmt.Errorf("publish fallback crash report: %w", err)
-		}
-	}
-	for range 100 {
-		var suffix [16]byte
-		if _, err := rand.Read(suffix[:]); err != nil {
-			return "", fmt.Errorf("generate fallback crash report name: %w", err)
-		}
-		candidate := base + "-" + hex.EncodeToString(suffix[:]) + filepath.Ext(timestampName)
-		if err := rename(root, tempName, candidate); err == nil {
-			return candidate, nil
-		} else if !errors.Is(err, os.ErrExist) {
-			return "", fmt.Errorf("publish fallback crash report: %w", err)
-		}
-	}
-	return "", fmt.Errorf("generate fallback crash report name: exhausted unique names")
-}
-
-func removeCrashTemp(hooks crashReportHooks, root *os.Root, name string) error {
-	if hooks.remove != nil {
-		return hooks.remove(root, name)
-	}
-	return root.Remove(name)
-}
-
-func createCrashTemp(root *os.Root) (*os.File, string, error) {
-	for range 100 {
-		var suffix [16]byte
-		if _, err := rand.Read(suffix[:]); err != nil {
-			return nil, "", fmt.Errorf("generate temporary crash report name: %w", err)
-		}
-		name := crashTempPrefix + hex.EncodeToString(suffix[:])
-		file, err := root.OpenFile(name, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0o600)
-		if err == nil {
-			return file, name, nil
-		}
-		if errors.Is(err, os.ErrExist) {
-			continue
-		}
-		return nil, "", fmt.Errorf("create temporary crash report: %w", err)
-	}
-	return nil, "", fmt.Errorf("create temporary crash report: exhausted unique names")
-}
-
-func crashPathUsesRoot(root *os.Root, dir string) bool {
-	bound, err := root.Stat(".")
-	if err != nil {
-		return false
-	}
-	current, err := os.Stat(filepath.Clean(dir))
-	return err == nil && os.SameFile(bound, current)
-}
-
-func openCrashDirectory(dir string) (*os.Root, error) {
-	clean := filepath.Clean(dir)
-	defaultDir := filepath.Clean(DefaultCrashDir())
-	parent := filepath.Dir(clean)
-	// The default layout shares ~/.zero with the daemon runtime fallback. Keep
-	// both the shared parent and the crash-report child private. Custom crash
-	// destinations are hardened at the caller-supplied boundary only.
-	if clean == defaultDir && filepath.Base(clean) == "crashes" && filepath.Base(parent) == ".zero" {
-		if err := privatedir.Ensure(parent); err != nil {
-			return nil, fmt.Errorf("secure crash report parent: %w", err)
-		}
-	}
-	root, err := privatedir.Open(clean)
-	if err != nil {
-		return nil, fmt.Errorf("secure crash report directory: %w", err)
-	}
-	return root, nil
-}
-
 // DefaultCrashDir is where crash reports are written by default.
 func DefaultCrashDir() string {
 	if home, err := os.UserHomeDir(); err == nil && home != "" {
@@ -260,22 +54,8 @@ func Recover(dir, label string, stderr io.Writer, code *int) {
 		return
 	}
 	stack := debug.Stack()
-	reportRecoveredCrash(stderr, code, recovered, stack, func() (string, error) {
-		return WriteCrashReport(dir, label, recovered, stack, time.Now())
-	})
-}
-
-func reportRecoveredCrash(stderr io.Writer, code *int, recovered any, stack []byte, write func() (string, error)) {
-	path, err := write()
-	if err == nil || errors.Is(err, ErrCrashReportCommitted) {
-		if path != "" {
-			fmt.Fprintf(stderr, "zero crashed: %v\nA crash report was saved to %s\n", recovered, path)
-		} else {
-			fmt.Fprintf(stderr, "zero crashed: %v\nA crash report was saved, but its current path could not be determined\n", recovered)
-		}
-		if err != nil {
-			fmt.Fprintf(stderr, "Warning: %v\n", err)
-		}
+	if path, err := WriteCrashReport(dir, label, recovered, stack, time.Now()); err == nil {
+		fmt.Fprintf(stderr, "zero crashed: %v\nA crash report was saved to %s\n", recovered, path)
 	} else {
 		fmt.Fprintf(stderr, "zero crashed: %v\n%s\n", recovered, stack)
 	}

internal/observability/crash_test.go

@@ -2,10 +2,7 @@ package observability
 
 import (
 	"bytes"
-	"errors"
 	"os"
-	"path/filepath"
-	"runtime"
 	"strings"
 	"testing"
 	"time"
@@ -30,400 +27,6 @@ func TestWriteAndFormatCrashReport(t *testing.T) {
 	}
 }
 
-func TestWriteCrashReportKeepsTwoReportsFromTheSameSecond(t *testing.T) {
-	dir := t.TempDir()
-	ts := time.Date(2026, 8, 30, 18, 0, 0, 0, time.UTC)
-	first, err := WriteCrashReport(dir, "cli", "first panic", []byte("first stack"), ts)
-	if err != nil {
-		t.Fatal(err)
-	}
-	second, err := WriteCrashReport(dir, "cli", "second panic", []byte("second stack"), ts)
-	if err != nil {
-		t.Fatalf("second report in the same second: %v", err)
-	}
-	if first == second {
-		t.Fatalf("same-second reports shared path %q", first)
-	}
-	firstData, err := os.ReadFile(first)
-	if err != nil {
-		t.Fatal(err)
-	}
-	secondData, err := os.ReadFile(second)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if !strings.Contains(string(firstData), "first panic") || strings.Contains(string(firstData), "second panic") {
-		t.Fatalf("first report was replaced: %q", firstData)
-	}
-	if !strings.Contains(string(secondData), "second panic") {
-		t.Fatalf("second report was not persisted: %q", secondData)
-	}
-}
-
-func TestWriteCrashReportCreatesPrivateDefaultDirectories(t *testing.T) {
-	home := t.TempDir()
-	t.Setenv("HOME", home)
-	t.Setenv("USERPROFILE", home)
-
-	dir := DefaultCrashDir()
-	if dir != filepath.Join(home, ".zero", "crashes") {
-		t.Fatalf("DefaultCrashDir = %q, want path beneath temporary home", dir)
-	}
-	if _, err := WriteCrashReport(dir, "cli", "boom", []byte("stack"), time.Now()); err != nil {
-		t.Fatalf("WriteCrashReport: %v", err)
-	}
-	if runtime.GOOS == "windows" {
-		return
-	}
-	for _, path := range []string{filepath.Join(home, ".zero"), dir} {
-		info, err := os.Stat(path)
-		if err != nil {
-			t.Fatal(err)
-		}
-		if got := info.Mode().Perm(); got&0o077 != 0 {
-			t.Fatalf("directory %s permissions = %04o, want owner-only", path, got)
-		}
-	}
-}
-
-func TestWriteCrashReportHardensPreexistingDefaultDirectories(t *testing.T) {
-	if runtime.GOOS == "windows" {
-		t.Skip("Windows DACL migration is covered by the daemon integration test")
-	}
-	home := t.TempDir()
-	t.Setenv("HOME", home)
-	t.Setenv("USERPROFILE", home)
-	dir := DefaultCrashDir()
-	if err := os.MkdirAll(dir, 0o755); err != nil {
-		t.Fatal(err)
-	}
-	for _, path := range []string{filepath.Join(home, ".zero"), dir} {
-		if err := os.Chmod(path, 0o755); err != nil {
-			t.Fatal(err)
-		}
-	}
-
-	if _, err := WriteCrashReport(dir, "cli", "boom", []byte("stack"), time.Now()); err != nil {
-		t.Fatalf("WriteCrashReport: %v", err)
-	}
-	for _, path := range []string{filepath.Join(home, ".zero"), dir} {
-		info, err := os.Stat(path)
-		if err != nil {
-			t.Fatal(err)
-		}
-		if got := info.Mode().Perm(); got&0o077 != 0 {
-			t.Fatalf("directory %s permissions = %04o after migration, want owner-only", path, got)
-		}
-	}
-}
-
-func TestWriteCrashReportBindsDirectoryDuringSwap(t *testing.T) {
-	parent := t.TempDir()
-	dir := filepath.Join(parent, "live")
-	movedDir := filepath.Join(parent, "moved")
-	if err := os.Mkdir(dir, 0o700); err != nil {
-		t.Fatal(err)
-	}
-
-	ts := time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC)
-	var swapErr error
-	path, err := writeCrashReport(dir, "cli", "secret panic", []byte("secret stack"), ts, crashReportHooks{
-		beforePublish: func() {
-			swapErr = os.Rename(dir, movedDir)
-			if swapErr != nil {
-				return
-			}
-			if err := os.Mkdir(dir, 0o700); err != nil {
-				t.Fatalf("create substitute crash directory: %v", err)
-			}
-		},
-	})
-	if err != nil {
-		t.Fatalf("writeCrashReport: %v", err)
-	}
-	if swapErr != nil {
-		if runtime.GOOS != "windows" {
-			t.Fatalf("swap crash directory: %v", swapErr)
-		}
-		if _, err := os.Stat(path); err != nil {
-			t.Fatalf("report missing after Windows blocked directory swap: %v", err)
-		}
-		return
-	}
-
-	if path != "" {
-		t.Fatalf("writeCrashReport returned stale path %q after directory swap", path)
-	}
-	reportName := "crash-" + ts.UTC().Format("20060102-150405") + ".log"
-	data, err := os.ReadFile(filepath.Join(movedDir, reportName))
-	if err != nil {
-		t.Fatalf("read report through originally bound directory: %v", err)
-	}
-	if !strings.Contains(string(data), "secret panic") {
-		t.Fatalf("report in bound directory missing panic: %q", data)
-	}
-	if _, err := os.Stat(filepath.Join(dir, reportName)); !errors.Is(err, os.ErrNotExist) {
-		t.Fatalf("substitute directory received crash report: %v", err)
-	}
-}
-
-func TestWriteCrashReportPublishesOnlyCompleteContent(t *testing.T) {
-	dir := t.TempDir()
-	ts := time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC)
-	finalPath := filepath.Join(dir, "crash-20260824-120000.log")
-	staged := make(chan struct{})
-	release := make(chan struct{})
-	result := make(chan crashWriteResult, 1)
-	go func() {
-		path, err := writeCrashReport(dir, "cli", "boom", []byte("complete stack"), ts, crashReportHooks{
-			beforePublish: func() {
-				close(staged)
-				<-release
-			},
-		})
-		result <- crashWriteResult{path: path, err: err}
-	}()
-	select {
-	case <-staged:
-	case written := <-result:
-		t.Fatalf("writeCrashReport returned before publication hook: %v", written.err)
-	case <-time.After(time.Second):
-		t.Fatal("writeCrashReport did not reach publication hook")
-	}
-	defer func() {
-		select {
-		case <-release:
-		default:
-			close(release)
-		}
-	}()
-	if _, err := os.Stat(finalPath); !errors.Is(err, os.ErrNotExist) {
-		t.Fatalf("final report visible before complete publication: %v", err)
-	}
-	close(release)
-	written := <-result
-	if written.err != nil {
-		t.Fatalf("writeCrashReport: %v", written.err)
-	}
-	data, err := os.ReadFile(written.path)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if !strings.Contains(string(data), "complete stack") {
-		t.Fatalf("published report is incomplete: %q", data)
-	}
-}
-
-func TestWriteCrashReportRemovesTempAfterWriteFailure(t *testing.T) {
-	dir := t.TempDir()
-	injected := errors.New("injected write failure")
-	_, err := writeCrashReport(dir, "cli", "boom", []byte("stack"), time.Now(), crashReportHooks{
-		write: func(*os.File, []byte) (int, error) { return 0, injected },
-	})
-	if !errors.Is(err, injected) {
-		t.Fatalf("writeCrashReport error = %v, want injected failure", err)
-	}
-	entries, err := os.ReadDir(dir)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if len(entries) != 0 {
-		t.Fatalf("crash directory contains partial files after failure: %v", entries)
-	}
-}
-
-func TestWriteCrashReportDoesNotOverwriteExistingReport(t *testing.T) {
-	dir := t.TempDir()
-	ts := time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC)
-	path := filepath.Join(dir, "crash-20260824-120000.log")
-	if err := os.WriteFile(path, []byte("existing"), 0o600); err != nil {
-		t.Fatal(err)
-	}
-	published, err := WriteCrashReport(dir, "cli", "boom", []byte("stack"), ts)
-	if err != nil {
-		t.Fatalf("WriteCrashReport with existing timestamp: %v", err)
-	}
-	if published == path {
-		t.Fatal("new report reused the occupied timestamp path")
-	}
-	data, err := os.ReadFile(path)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if string(data) != "existing" {
-		t.Fatalf("existing report overwritten: %q", data)
-	}
-	entries, err := os.ReadDir(dir)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if len(entries) != 2 {
-		t.Fatalf("crash directory should contain existing and uniquely published reports: %v", entries)
-	}
-}
-
-func TestWriteCrashReportPreservesPathAfterCommittedCleanupWarning(t *testing.T) {
-	dir := t.TempDir()
-	ts := time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC)
-	injected := errors.New("injected cleanup failure")
-	path, err := writeCrashReport(dir, "cli", "boom", []byte("complete stack"), ts, crashReportHooks{
-		remove: func(*os.Root, string) error { return injected },
-	})
-	if !errors.Is(err, ErrCrashReportCommitted) || !errors.Is(err, injected) {
-		t.Fatalf("writeCrashReport error = %v, want committed cleanup warning", err)
-	}
-	wantPath := filepath.Join(dir, "crash-20260824-120000.log")
-	if path != wantPath {
-		t.Fatalf("writeCrashReport path = %q, want %q", path, wantPath)
-	}
-	data, readErr := os.ReadFile(path)
-	if readErr != nil {
-		t.Fatalf("read committed crash report: %v", readErr)
-	}
-	if !strings.Contains(string(data), "complete stack") {
-		t.Fatalf("committed crash report is incomplete: %q", data)
-	}
-}
-
-func TestWriteCrashReportDoesNotReturnStalePathWithCleanupWarning(t *testing.T) {
-	parent := t.TempDir()
-	dir := filepath.Join(parent, "live")
-	movedDir := filepath.Join(parent, "moved")
-	if err := os.Mkdir(dir, 0o700); err != nil {
-		t.Fatal(err)
-	}
-	injected := errors.New("injected cleanup failure")
-	ts := time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC)
-	var swapErr error
-	path, err := writeCrashReport(dir, "cli", "boom", []byte("complete stack"), ts, crashReportHooks{
-		beforePublish: func() {
-			swapErr = os.Rename(dir, movedDir)
-			if swapErr == nil {
-				if err := os.Mkdir(dir, 0o700); err != nil {
-					t.Fatalf("create substitute crash directory: %v", err)
-				}
-			}
-		},
-		remove: func(*os.Root, string) error { return injected },
-	})
-	if swapErr != nil {
-		if runtime.GOOS == "windows" {
-			t.Skipf("Windows kept the open crash directory from being renamed: %v", swapErr)
-		}
-		t.Fatalf("swap crash directory: %v", swapErr)
-	}
-	if !errors.Is(err, ErrCrashReportCommitted) || !errors.Is(err, injected) {
-		t.Fatalf("writeCrashReport error = %v, want committed cleanup warning", err)
-	}
-	if path != "" {
-		t.Fatalf("writeCrashReport returned stale path %q after directory swap", path)
-	}
-	report := filepath.Join(movedDir, "crash-20260824-120000.log")
-	data, readErr := os.ReadFile(report)
-	if readErr != nil {
-		t.Fatalf("read committed report through moved directory: %v", readErr)
-	}
-	if !strings.Contains(string(data), "complete stack") {
-		t.Fatalf("committed report is incomplete: %q", data)
-	}
-}
-
-func TestWriteCrashReportFallsBackWhenHardLinksAreUnavailable(t *testing.T) {
-	dir := t.TempDir()
-	ts := time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC)
-	unsupported := errors.New("hard links unavailable")
-	var collisionName string
-	path, err := writeCrashReport(dir, "cli", "boom", []byte("complete stack"), ts, crashReportHooks{
-		link: func(root *os.Root, oldname, _ string) error {
-			suffix := strings.TrimPrefix(oldname, crashTempPrefix)
-			collisionName = "crash-20260824-120000-" + suffix + ".log"
-			if err := root.WriteFile(collisionName, []byte("existing"), 0o600); err != nil {
-				t.Fatalf("create fallback-name collision: %v", err)
-			}
-			return unsupported
-		},
-	})
-	if err != nil {
-		t.Fatalf("writeCrashReport fallback: %v", err)
-	}
-	if path == filepath.Join(dir, collisionName) {
-		t.Fatalf("fallback replaced the existing report %q", collisionName)
-	}
-	if !strings.HasPrefix(filepath.Base(path), "crash-20260824-120000-") {
-		t.Fatalf("fallback path = %q, want timestamp and random suffix", path)
-	}
-	data, readErr := os.ReadFile(path)
-	if readErr != nil {
-		t.Fatalf("read fallback crash report: %v", readErr)
-	}
-	if !strings.Contains(string(data), "complete stack") {
-		t.Fatalf("fallback crash report is incomplete: %q", data)
-	}
-	existing, readErr := os.ReadFile(filepath.Join(dir, collisionName))
-	if readErr != nil {
-		t.Fatalf("read existing collision: %v", readErr)
-	}
-	if string(existing) != "existing" {
-		t.Fatalf("existing fallback collision was overwritten: %q", existing)
-	}
-	entries, readErr := os.ReadDir(dir)
-	if readErr != nil {
-		t.Fatal(readErr)
-	}
-	if len(entries) != 2 {
-		t.Fatalf("crash directory contains partial files after fallback: %v", entries)
-	}
-}
-
-func TestWriteCrashReportFallbackDoesNotReplaceCommitTimeCollision(t *testing.T) {
-	dir := t.TempDir()
-	ts := time.Date(2026, 8, 24, 12, 0, 0, 0, time.UTC)
-	unsupported := errors.New("hard links unavailable")
-	var collisionName string
-	attempts := 0
-	path, err := writeCrashReport(dir, "cli", "boom", []byte("complete stack"), ts, crashReportHooks{
-		link: func(*os.Root, string, string) error { return unsupported },
-		renameNoReplace: func(root *os.Root, oldname, newname string) error {
-			attempts++
-			if attempts == 1 {
-				collisionName = newname
-				if err := root.WriteFile(newname, []byte("concurrent report"), 0o600); err != nil {
-					t.Fatalf("create commit-time collision: %v", err)
-				}
-			}
-			return renameNoReplace(root, oldname, newname)
-		},
-	})
-	if err != nil {
-		t.Fatalf("writeCrashReport fallback: %v", err)
-	}
-	if attempts < 2 {
-		t.Fatalf("fallback rename attempts = %d, want collision retry", attempts)
-	}
-	if filepath.Base(path) == collisionName {
-		t.Fatalf("fallback replaced the concurrent report %q", collisionName)
-	}
-	existing, err := os.ReadFile(filepath.Join(dir, collisionName))
-	if err != nil {
-		t.Fatal(err)
-	}
-	if string(existing) != "concurrent report" {
-		t.Fatalf("concurrent report overwritten: %q", existing)
-	}
-	published, err := os.ReadFile(path)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if !strings.Contains(string(published), "complete stack") {
-		t.Fatalf("published fallback is incomplete: %q", published)
-	}
-}
-
-type crashWriteResult struct {
-	path string
-	err  error
-}
-
 func TestRecoverCapturesPanic(t *testing.T) {
 	dir := t.TempDir()
 	var stderr bytes.Buffer
@@ -460,25 +63,3 @@ func TestRecoverNoPanicIsNoop(t *testing.T) {
 		t.Fatalf("unexpected output without a panic: %q", stderr.String())
 	}
 }
-
-func TestReportRecoveredCrashReportsCommittedCleanupWarning(t *testing.T) {
-	var stderr bytes.Buffer
-	code := 0
-	injected := errors.New("injected cleanup failure")
-	reportRecoveredCrash(&stderr, &code, "kaboom", []byte("secret stack"), func() (string, error) {
-		return "/tmp/crash.log", &crashReportCommittedError{cause: injected}
-	})
-
-	if code != crashExitCode {
-		t.Fatalf("exit code = %d, want %d", code, crashExitCode)
-	}
-	output := stderr.String()
-	for _, want := range []string{"kaboom", "saved to /tmp/crash.log", "Warning:", injected.Error()} {
-		if !strings.Contains(output, want) {
-			t.Fatalf("crash notice missing %q: %q", want, output)
-		}
-	}
-	if strings.Contains(output, "secret stack") {
-		t.Fatalf("committed report warning fell back to inline stack: %q", output)
-	}
-}

internal/observability/rename_noreplace_darwin.go

@@ -1,19 +0,0 @@
-//go:build darwin
-
-package observability
-
-import (
-	"fmt"
-	"os"
-
-	"golang.org/x/sys/unix"
-)
-
-func renameNoReplace(root *os.Root, oldname, newname string) error {
-	directory, err := root.Open(".")
-	if err != nil {
-		return fmt.Errorf("open crash directory for publication: %w", err)
-	}
-	defer directory.Close()
-	return unix.RenameatxNp(int(directory.Fd()), oldname, int(directory.Fd()), newname, unix.RENAME_EXCL)
-}

internal/observability/rename_noreplace_linux.go

@@ -1,19 +0,0 @@
-//go:build linux
-
-package observability
-
-import (
-	"fmt"
-	"os"
-
-	"golang.org/x/sys/unix"
-)
-
-func renameNoReplace(root *os.Root, oldname, newname string) error {
-	directory, err := root.Open(".")
-	if err != nil {
-		return fmt.Errorf("open crash directory for publication: %w", err)
-	}
-	defer directory.Close()
-	return unix.Renameat2(int(directory.Fd()), oldname, int(directory.Fd()), newname, unix.RENAME_NOREPLACE)
-}

internal/observability/rename_noreplace_other.go

@@ -1,12 +0,0 @@
-//go:build !darwin && !linux && !windows
-
-package observability
-
-import (
-	"errors"
-	"os"
-)
-
-func renameNoReplace(*os.Root, string, string) error {
-	return errors.ErrUnsupported
-}

internal/observability/rename_noreplace_windows.go

@@ -1,84 +0,0 @@
-//go:build windows
-
-package observability
-
-import (
-	"errors"
-	"os"
-	"unsafe"
-
-	"golang.org/x/sys/windows"
-)
-
-type fileRenameInformation struct {
-	replaceIfExists uint32
-	rootDirectory   windows.Handle
-	fileNameLength  uint32
-	fileName        [1]uint16
-}
-
-func renameNoReplace(root *os.Root, oldname, newname string) (returnErr error) {
-	directory, err := root.Open(".")
-	if err != nil {
-		return err
-	}
-	defer directory.Close()
-	raw, err := directory.SyscallConn()
-	if err != nil {
-		return err
-	}
-	if err := raw.Control(func(rawHandle uintptr) {
-		rootHandle := windows.Handle(rawHandle)
-		oldObjectName, nameErr := windows.NewNTUnicodeString(oldname)
-		if nameErr != nil {
-			returnErr = nameErr
-			return
-		}
-		attributes := &windows.OBJECT_ATTRIBUTES{
-			Length:        uint32(unsafe.Sizeof(windows.OBJECT_ATTRIBUTES{})),
-			RootDirectory: rootHandle,
-			ObjectName:    oldObjectName,
-			Attributes:    windows.OBJ_CASE_INSENSITIVE | windows.OBJ_DONT_REPARSE,
-		}
-		var source windows.Handle
-		var status windows.IO_STATUS_BLOCK
-		returnErr = windows.NtCreateFile(
-			&source,
-			windows.DELETE|windows.SYNCHRONIZE,
-			attributes,
-			&status,
-			nil,
-			0,
-			windows.FILE_SHARE_READ|windows.FILE_SHARE_WRITE|windows.FILE_SHARE_DELETE,
-			windows.FILE_OPEN,
-			windows.FILE_NON_DIRECTORY_FILE|windows.FILE_SYNCHRONOUS_IO_NONALERT|windows.FILE_OPEN_REPARSE_POINT,
-			0,
-			0,
-		)
-		if returnErr != nil {
-			return
-		}
-		defer windows.CloseHandle(source)
-
-		newName, nameErr := windows.UTF16FromString(newname)
-		if nameErr != nil {
-			returnErr = nameErr
-			return
-		}
-		nameBytes := (len(newName) - 1) * 2
-		var layout fileRenameInformation
-		bufferSize := int(unsafe.Offsetof(layout.fileName)) + nameBytes
-		buffer := make([]byte, bufferSize)
-		info := (*fileRenameInformation)(unsafe.Pointer(&buffer[0]))
-		info.rootDirectory = rootHandle
-		info.fileNameLength = uint32(nameBytes)
-		copy((*[windows.MAX_LONG_PATH]uint16)(unsafe.Pointer(&info.fileName[0]))[:nameBytes/2:nameBytes/2], newName)
-		returnErr = windows.NtSetInformationFile(source, &status, &buffer[0], uint32(bufferSize), windows.FileRenameInformation)
-	}); err != nil {
-		return err
-	}
-	if errors.Is(returnErr, windows.STATUS_OBJECT_NAME_COLLISION) || errors.Is(returnErr, windows.STATUS_OBJECT_NAME_EXISTS) {
-		return os.ErrExist
-	}
-	return returnErr
-}

internal/privatedir/privatedir.go

@@ -1,85 +0,0 @@
-// Package privatedir creates and safely hardens current-user-owned state
-// directories without applying permission changes through a path-only check.
-package privatedir
-
-import (
-	"errors"
-	"fmt"
-	"os"
-	"path/filepath"
-)
-
-// Ensure creates path when needed and enforces owner-only access. Existing
-// directories are hardened only after ownership is verified through a bound
-// directory handle; foreign-owned paths fail closed.
-func Ensure(path string) error {
-	root, err := Open(path)
-	if err != nil {
-		return err
-	}
-	if err := root.Close(); err != nil {
-		return fmt.Errorf("close private directory: %w", err)
-	}
-	return nil
-}
-
-// Open creates path when needed, enforces owner-only access, and returns a
-// traversal-resistant handle that callers can retain across subsequent I/O.
-func Open(path string) (*os.Root, error) {
-	absolute, err := filepath.Abs(path)
-	if err != nil {
-		return nil, fmt.Errorf("resolve private directory: %w", err)
-	}
-	if err := os.MkdirAll(absolute, 0o700); err != nil {
-		return nil, fmt.Errorf("create private directory: %w", err)
-	}
-	before, err := os.Lstat(absolute)
-	if err != nil {
-		return nil, fmt.Errorf("inspect private directory entry: %w", err)
-	}
-	if before.Mode()&os.ModeSymlink != 0 {
-		return nil, fmt.Errorf("private directory entry is a symbolic link")
-	}
-	if !before.IsDir() {
-		return nil, fmt.Errorf("private directory path is not a directory")
-	}
-	root, err := os.OpenRoot(absolute)
-	if err != nil {
-		return nil, fmt.Errorf("open private directory: %w", err)
-	}
-	opened, err := root.Stat(".")
-	if err != nil {
-		_ = root.Close()
-		return nil, fmt.Errorf("inspect opened private directory: %w", err)
-	}
-	after, err := os.Lstat(absolute)
-	if err != nil {
-		_ = root.Close()
-		return nil, fmt.Errorf("reinspect private directory entry: %w", err)
-	}
-	if after.Mode()&os.ModeSymlink != 0 || !os.SameFile(opened, after) {
-		_ = root.Close()
-		return nil, fmt.Errorf("private directory entry changed while opening")
-	}
-	if err := harden(root); err != nil {
-		closeErr := root.Close()
-		if closeErr != nil {
-			return nil, errors.Join(err, fmt.Errorf("close private directory: %w", closeErr))
-		}
-		return nil, err
-	}
-	current, err := os.Lstat(absolute)
-	if err != nil || current.Mode()&os.ModeSymlink != 0 || !os.SameFile(opened, current) {
-		closeErr := root.Close()
-		if err == nil {
-			err = fmt.Errorf("private directory entry changed while hardening")
-		} else {
-			err = fmt.Errorf("verify private directory entry after hardening: %w", err)
-		}
-		if closeErr != nil {
-			err = errors.Join(err, fmt.Errorf("close private directory: %w", closeErr))
-		}
-		return nil, err
-	}
-	return root, nil
-}

internal/privatedir/privatedir_test.go

@@ -1,35 +0,0 @@
-package privatedir
-
-import (
-	"os"
-	"path/filepath"
-	"runtime"
-	"strings"
-	"testing"
-)
-
-func TestOpenRejectsFinalDirectorySymlinkWithoutHardeningTarget(t *testing.T) {
-	if runtime.GOOS == "windows" {
-		t.Skip("creating directory symlinks requires privileges on some Windows runners")
-	}
-	parent := t.TempDir()
-	target := filepath.Join(parent, "target")
-	if err := os.Mkdir(target, 0o755); err != nil {
-		t.Fatal(err)
-	}
-	link := filepath.Join(parent, "private")
-	if err := os.Symlink(target, link); err != nil {
-		t.Fatal(err)
-	}
-
-	if _, err := Open(link); err == nil || !strings.Contains(err.Error(), "symbolic link") {
-		t.Fatalf("Open symlink error = %v, want symbolic-link rejection", err)
-	}
-	info, err := os.Stat(target)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if got := info.Mode().Perm(); got != 0o755 {
-		t.Fatalf("symlink target permissions = %04o, want unchanged 0755", got)
-	}
-}

internal/privatedir/privatedir_unix.go

@@ -1,47 +0,0 @@
-//go:build !windows
-
-package privatedir
-
-import (
-	"errors"
-	"fmt"
-	"os"
-	"syscall"
-)
-
-func harden(root *os.Root) (returnErr error) {
-	directory, err := root.Open(".")
-	if err != nil {
-		return fmt.Errorf("open private directory hardening handle: %w", err)
-	}
-	defer func() {
-		if err := directory.Close(); err != nil {
-			returnErr = errors.Join(returnErr, fmt.Errorf("close private directory hardening handle: %w", err))
-		}
-	}()
-	info, err := directory.Stat()
-	if err != nil {
-		return fmt.Errorf("inspect private directory before hardening: %w", err)
-	}
-	if !info.IsDir() {
-		return fmt.Errorf("private directory path is not a directory")
-	}
-	stat, ok := info.Sys().(*syscall.Stat_t)
-	if !ok {
-		return fmt.Errorf("private directory ownership metadata is unavailable")
-	}
-	if int(stat.Uid) != os.Geteuid() {
-		return fmt.Errorf("private directory is owned by uid %d, not the current user", stat.Uid)
-	}
-	if err := directory.Chmod(0o700); err != nil {
-		return fmt.Errorf("harden private directory permissions: %w", err)
-	}
-	info, err = directory.Stat()
-	if err != nil {
-		return fmt.Errorf("verify private directory permissions: %w", err)
-	}
-	if info.Mode().Perm()&0o077 != 0 {
-		return fmt.Errorf("private directory permissions are %04o, want owner-only", info.Mode().Perm())
-	}
-	return nil
-}

internal/privatedir/privatedir_windows.go

@@ -1,135 +0,0 @@
-//go:build windows
-
-package privatedir
-
-import (
-	"errors"
-	"fmt"
-	"os"
-	"unsafe"
-
-	"golang.org/x/sys/windows"
-)
-
-func harden(root *os.Root) (returnErr error) {
-	directory, err := root.Open(".")
-	if err != nil {
-		return fmt.Errorf("open private directory hardening handle: %w", err)
-	}
-	defer func() {
-		if err := directory.Close(); err != nil {
-			returnErr = errors.Join(returnErr, fmt.Errorf("close private directory hardening handle: %w", err))
-		}
-	}()
-	raw, err := directory.SyscallConn()
-	if err != nil {
-		return fmt.Errorf("access private directory hardening handle: %w", err)
-	}
-	// Root.Open uses NtCreateFile, so ReOpenFile cannot accept its handle. An
-	// empty relative NT object name reopens the bound directory itself with the
-	// security rights needed for the DACL update and no pathname re-resolution.
-	var securityHandle windows.Handle
-	var openErr error
-	if err := raw.Control(func(rawHandle uintptr) {
-		objectName, nameErr := windows.NewNTUnicodeString("")
-		if nameErr != nil {
-			openErr = nameErr
-			return
-		}
-		openErr = windows.NtCreateFile(
-			&securityHandle,
-			windows.READ_CONTROL|windows.WRITE_DAC|windows.FILE_READ_ATTRIBUTES|windows.SYNCHRONIZE,
-			&windows.OBJECT_ATTRIBUTES{
-				Length:        uint32(unsafe.Sizeof(windows.OBJECT_ATTRIBUTES{})),
-				RootDirectory: windows.Handle(rawHandle),
-				ObjectName:    objectName,
-				Attributes:    windows.OBJ_CASE_INSENSITIVE | windows.OBJ_DONT_REPARSE,
-			},
-			&windows.IO_STATUS_BLOCK{},
-			nil,
-			windows.FILE_ATTRIBUTE_DIRECTORY,
-			windows.FILE_SHARE_READ|windows.FILE_SHARE_WRITE|windows.FILE_SHARE_DELETE,
-			windows.FILE_OPEN,
-			windows.FILE_DIRECTORY_FILE|windows.FILE_SYNCHRONOUS_IO_NONALERT|windows.FILE_OPEN_REPARSE_POINT|windows.FILE_OPEN_FOR_BACKUP_INTENT,
-			0,
-			0,
-		)
-	}); err != nil {
-		return fmt.Errorf("open private directory security handle: %w", err)
-	}
-	if openErr != nil {
-		return fmt.Errorf("open private directory with security access: %w", openErr)
-	}
-	if securityHandle == 0 || securityHandle == windows.InvalidHandle {
-		return fmt.Errorf("open private directory with security access: invalid handle")
-	}
-	defer func() {
-		if err := windows.CloseHandle(securityHandle); err != nil {
-			returnErr = errors.Join(returnErr, fmt.Errorf("close private directory security handle: %w", err))
-		}
-	}()
-
-	token := windows.GetCurrentProcessToken()
-	user, err := token.GetTokenUser()
-	if err != nil {
-		return fmt.Errorf("resolve current Windows user: %w", err)
-	}
-	tokenOwner, err := windowsTokenOwner(token)
-	if err != nil {
-		return fmt.Errorf("resolve current Windows token owner: %w", err)
-	}
-	current, err := windows.GetSecurityInfo(securityHandle, windows.SE_FILE_OBJECT, windows.OWNER_SECURITY_INFORMATION)
-	if err != nil {
-		return fmt.Errorf("read private directory owner before hardening: %w", err)
-	}
-	owner, _, err := current.Owner()
-	if err != nil {
-		return fmt.Errorf("read private directory owner before hardening: %w", err)
-	}
-	if owner == nil || (!owner.Equals(user.User.Sid) && !owner.Equals(tokenOwner)) {
-		return fmt.Errorf("private directory is not owned by the current Windows token")
-	}
-	desired, err := windows.SecurityDescriptorFromString(
-		fmt.Sprintf("O:%sD:P(A;OICI;GA;;;%s)(A;OICI;GA;;;SY)", user.User.Sid.String(), user.User.Sid.String()),
-	)
-	if err != nil {
-		return fmt.Errorf("build private Windows directory DACL: %w", err)
-	}
-	dacl, _, err := desired.DACL()
-	if err != nil {
-		return fmt.Errorf("read private Windows directory DACL: %w", err)
-	}
-	if err := windows.SetSecurityInfo(
-		securityHandle,
-		windows.SE_FILE_OBJECT,
-		windows.DACL_SECURITY_INFORMATION|windows.PROTECTED_DACL_SECURITY_INFORMATION,
-		nil,
-		nil,
-		dacl,
-		nil,
-	); err != nil {
-		return fmt.Errorf("harden private Windows directory DACL: %w", err)
-	}
-	return nil
-}
-
-type tokenOwnerInfo struct {
-	owner *windows.SID
-}
-
-func windowsTokenOwner(token windows.Token) (*windows.SID, error) {
-	var size uint32
-	err := windows.GetTokenInformation(token, windows.TokenOwner, nil, 0, &size)
-	if err != windows.ERROR_INSUFFICIENT_BUFFER {
-		return nil, err
-	}
-	buffer := make([]byte, size)
-	if err := windows.GetTokenInformation(token, windows.TokenOwner, &buffer[0], size, &size); err != nil {
-		return nil, err
-	}
-	owner := (*tokenOwnerInfo)(unsafe.Pointer(&buffer[0])).owner
-	if owner == nil {
-		return nil, errors.New("windows access token has no default owner")
-	}
-	return owner.Copy()
-}

internal/sessions/replay.go

@@ -226,20 +226,11 @@ func CompactionPayloadFromPlan(summary string, plan CompactionPlan) (CompactionP
 }
 
 func (store *Store) ReadRehydratedEvents(sessionID string) ([]Event, error) {
-	events, _, err := store.ReadRehydratedEventsWithPresence(sessionID)
-	return events, err
-}
-
-// ReadRehydratedEventsWithPresence carries the underlying event-log presence
-// through compaction projection without changing ReadRehydratedEvents' existing
-// empty-on-missing contract.
-func (store *Store) ReadRehydratedEventsWithPresence(sessionID string) ([]Event, bool, error) {
-	events, present, err := store.ReadEventsWithPresence(sessionID)
+	events, err := store.ReadEvents(sessionID)
 	if err != nil {
-		return nil, present, err
+		return nil, err
 	}
-	rehydrated, err := RehydrateEvents(events)
-	return rehydrated, present, err
+	return RehydrateEvents(events)
 }
 
 func (store *Store) ReadReplayEvents(sessionID string) ([]Event, error) {

internal/sessions/store.go

@@ -813,24 +813,15 @@ func (store *Store) UpdateModel(sessionID string, modelID string) (Metadata, err
 }
 
 func (store *Store) ReadEvents(sessionID string) ([]Event, error) {
-	events, _, err := store.ReadEventsWithPresence(sessionID)
-	return events, err
-}
-
-// ReadEventsWithPresence preserves the distinction between an intentionally
-// empty event log and a missing one. Most readers accept both as empty history,
-// but activation protocols that promise to restore previously populated
-// context need the stronger signal.
-func (store *Store) ReadEventsWithPresence(sessionID string) ([]Event, bool, error) {
 	if !ValidSessionID(sessionID) {
-		return nil, false, fmt.Errorf("invalid zero session id %q", sessionID)
+		return nil, fmt.Errorf("invalid zero session id %q", sessionID)
 	}
 	data, err := os.ReadFile(store.eventsPath(sessionID))
 	if err != nil {
 		if errors.Is(err, os.ErrNotExist) {
-			return []Event{}, false, nil
+			return []Event{}, nil
 		}
-		return nil, false, fmt.Errorf("read zero session events: %w", err)
+		return nil, fmt.Errorf("read zero session events: %w", err)
 	}
 	// A genuine torn tail is an INCOMPLETE final write — a crash mid-append leaves
 	// the last line without its terminating newline. If the file ends with a
@@ -860,11 +851,11 @@ func (store *Store) ReadEventsWithPresence(sessionID string) ([]Event, bool, err
 			if index == lastNonEmpty && tornTailPossible {
 				break
 			}
-			return nil, true, fmt.Errorf("invalid json in zero session %s %s at line %d: %w", sessionID, EventsFile, index+1, err)
+			return nil, fmt.Errorf("invalid json in zero session %s %s at line %d: %w", sessionID, EventsFile, index+1, err)
 		}
 		events = append(events, event)
 	}
-	return events, true, nil
+	return events, nil
 }
 
 func (store *Store) timestamp() string {

internal/tui/command_center.go

@@ -8,6 +8,7 @@ import (
 	"strconv"
 	"strings"
 	"time"
+	"unicode"
 
 	tea "charm.land/bubbletea/v2"
 
@@ -365,17 +366,30 @@ func (defaultModelSwitchCompactionPolicy) BeforeModelSwitch(request modelSwitchC
 
 var modelSwitchCompactionGuard modelSwitchCompactionPolicy = defaultModelSwitchCompactionPolicy{}
 
-// sanitizeCardField strips the card protocol's separator bytes from
-// user-controlled values (titles can legally contain anything --session-title
-// was given), so a hostile or accidental \x1f / newline cannot shift fields
-// or leak control characters into the transcript.
+// sanitizeCardField strips the card protocol's separator byte and every
+// control rune from user-controlled values (titles can legally contain
+// anything --session-title was given, and a directory name can legally
+// contain an ESC byte on Unix). Line separators and tabs become spaces so
+// words stay apart; the remaining controls — ESC/CSI/OSC initiators, BEL, BS,
+// VT, NEL, NUL — are dropped outright, since any of them can repaint the
+// terminal or shift cells when the value lands in a rendered row.
 func sanitizeCardField(value string) string {
-	value = strings.ReplaceAll(value, sessionsCardFieldSep, " ")
-	value = strings.ReplaceAll(value, "\n", " ")
-	return strings.ReplaceAll(value, "\x00", "")
+	var out strings.Builder
+	for _, r := range value {
+		switch {
+		case r == '\x1f' || r == '\n' || r == '\r' || r == '\t':
+			out.WriteRune(' ')
+		case unicode.IsControl(r):
+		default:
+			out.WriteRune(r)
+		}
+	}
+	return out.String()
 }
 
-// relativeAge renders an RFC3339 timestamp as a short age ("2h ago"); ""
+// relativeAge renders an RFC3339 timestamp as a short age ("2h ago"), falling
+// back to the month/day this year and the bare date for sessions older than a
+// month, so deep history reads as a calendar date rather than "400d ago"; ""
 // when the timestamp does not parse, so the card simply omits it.
 func relativeAge(timestamp string, now time.Time) string {
 	parsed, err := time.Parse(time.RFC3339, strings.TrimSpace(timestamp))
@@ -385,14 +399,19 @@ func relativeAge(timestamp string, now time.Time) string {
 	age := now.Sub(parsed)
 	switch {
 	case age < time.Minute:
-		return "just now"
+		return "now"
 	case age < time.Hour:
 		return fmt.Sprintf("%dm ago", int(age.Minutes()))
 	case age < 24*time.Hour:
 		return fmt.Sprintf("%dh ago", int(age.Hours()))
-	default:
+	case age <= 30*24*time.Hour:
 		return fmt.Sprintf("%dd ago", int(age.Hours()/24))
 	}
+	parsed, now = parsed.Local(), now.Local()
+	if parsed.Year() == now.Year() {
+		return parsed.Format("Jan _2")
+	}
+	return parsed.Format("2006-01-02")
 }
 
 // handleModelCommand applies a model switch against the ACTIVE provider (the

internal/tui/model_test.go

@@ -1087,16 +1087,16 @@ func TestResumeCommandListsRecentSessions(t *testing.T) {
 }
 
 func TestSessionPickerLabelAlignsTitles(t *testing.T) {
-	today := sessionPickerLabel("20:47:50", "Today title")
-	older := sessionPickerLabel("Jul 24 10:47", "Older title")
+	recent := sessionPickerLabel("2h ago", "Recent title")
+	older := sessionPickerLabel("2006-01-02", "Older title")
 
-	todayColumn := strings.Index(today, "Today title")
+	recentColumn := strings.Index(recent, "Recent title")
 	olderColumn := strings.Index(older, "Older title")
-	if todayColumn < 0 || olderColumn < 0 {
-		t.Fatalf("sessionPickerLabel omitted a title: today=%q older=%q", today, older)
+	if recentColumn < 0 || olderColumn < 0 {
+		t.Fatalf("sessionPickerLabel omitted a title: recent=%q older=%q", recent, older)
 	}
-	if todayColumn != olderColumn {
-		t.Fatalf("title columns differ: today=%d (%q), older=%d (%q)", todayColumn, today, olderColumn, older)
+	if recentColumn != olderColumn {
+		t.Fatalf("title columns differ: recent=%d (%q), older=%d (%q)", recentColumn, recent, olderColumn, older)
 	}
 }
 

internal/tui/mouse.go

@@ -513,10 +513,11 @@ func (m *model) selectGenericPickerAtMouse(msg tea.MouseMsg) (mouseSelectionTarg
 			return mouseSelectionTarget{}, false
 		}
 	}
-	maxVisible := minInt(pickerOverlayMaxVisible, len(m.picker.items))
+	maxVisible := pickerMaxVisible(m.picker, width)
 	selected := clampInt(m.picker.selected, 0, len(m.picker.items)-1)
 	start := selectableListStart(len(m.picker.items), maxVisible, selected)
 	visible := m.picker.items[start : start+maxVisible]
+	details := pickerShowsDetails(m.picker, width)
 	// y=0 titled top border, y=1 search line, y=2 separator; rows begin at y=3.
 	line := 3
 	lastGroup := ""
@@ -528,12 +529,18 @@ func (m *model) selectGenericPickerAtMouse(msg tea.MouseMsg) (mouseSelectionTarg
 			line++
 			lastGroup = item.Group
 		}
-		if hit.y == line {
+		// A rendered detail line belongs to its item: a click anywhere on the
+		// two-line block selects the same row.
+		rowLines := 1
+		if details && item.Detail != "" {
+			rowLines = 2
+		}
+		if hit.y >= line && hit.y < line+rowLines {
 			index := start + offset
 			m.picker.selected = index
 			return mouseSelectionTarget{Scope: "picker", Kind: int(m.picker.kind), Value: item.Value, Index: index}, true
 		}
-		line++
+		line += rowLines
 	}
 	return mouseSelectionTarget{}, false
 }

internal/tui/picker.go

@@ -34,12 +34,15 @@ const (
 // pickerItem is one selectable row: Label is shown, Value is passed to the
 // underlying command handler when chosen. Meta is the optional right-aligned
 // readout (ctx window · capabilities); the dot flags mark provider locality
-// for model rows (accent = remote, blue = local).
+// for model rows (accent = remote, blue = local). Detail is an optional faint
+// second line under the row (project · model · size for sessions), rendered
+// only on medium-and-wider tiers where the extra line reads cleanly.
 type pickerItem struct {
 	Group    string
 	Label    string
 	Value    string
 	Meta     string
+	Detail   string
 	Provider string // display tag (catalog id / locality)
 	// OwnerProvider is the saved provider profile name a model belongs to, so the
 	// /model picker can switch providers when a model from a non-active provider is
@@ -167,7 +170,7 @@ func (p *commandPicker) applyQuery() {
 // the joined haystack, and a fuzzy subsequence is the last-resort match.
 func scorePickerItem(item pickerItem, query string) (int, bool) {
 	label := strings.ToLower(item.Label)
-	hay := strings.ToLower(strings.Join([]string{item.Group, item.Label, item.Value, item.Meta}, " "))
+	hay := strings.ToLower(strings.Join([]string{item.Group, item.Label, item.Value, item.Meta, item.Detail}, " "))
 	switch {
 	case label == query:
 		return 0, true

internal/tui/rendering_lime_test.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 	"testing"
 	"time"
+	"unicode"
 
 	"charm.land/lipgloss/v2"
 	"github.com/charmbracelet/colorprofile"
@@ -1973,8 +1974,27 @@ func TestPermissionCollapseIsRunScoped(t *testing.T) {
 }
 
 func TestSessionsCardFieldsAreSanitized(t *testing.T) {
-	if got := sanitizeCardField("evil\x1ftitle\nwith\x00bytes"); strings.ContainsAny(got, "\x1f\n\x00") {
-		t.Fatalf("sanitizeCardField left separator bytes: %q", got)
+	inputs := []string{
+		"evil\x1ftitle",
+		"line\nbreak",
+		"line\rbreak",
+		"nul\x00byte",
+		"esc\x1b[31mred",
+		"csi\x1b[2J\x1b[H",
+		"osc\x1b]0;pwned\a",
+		"bell\aring",
+		"back\bspace",
+		"tab\there",
+		"vert\vtab",
+		"nel\u0085here",
+	}
+	for _, input := range inputs {
+		got := sanitizeCardField(input)
+		for _, r := range got {
+			if unicode.IsControl(r) {
+				t.Fatalf("sanitizeCardField(%q) left control rune %q in %q", input, r, got)
+			}
+		}
 	}
 }
 

internal/tui/session.go

@@ -8,7 +8,6 @@ import (
 	"path/filepath"
 	"runtime"
 	"strings"
-	"time"
 
 	"github.com/Gitlawb/zero/internal/agent"
 	"github.com/Gitlawb/zero/internal/execution"
@@ -360,28 +359,10 @@ func (m model) formatResumeSummary(session sessions.Metadata, eventCount int) st
 	})
 }
 
-// sessionWhen formats a session's RFC3339 timestamp for the picker: a precise
-// clock time (with seconds) for today so same-minute sessions stay distinct, the
-// month/day and time earlier this year, else the date. Empty on a parse error.
-func sessionWhen(timestamp string, now time.Time) string {
-	parsed, err := time.Parse(time.RFC3339, strings.TrimSpace(timestamp))
-	if err != nil {
-		return ""
-	}
-	parsed, now = parsed.Local(), now.Local()
-	switch {
-	case parsed.Year() == now.Year() && parsed.YearDay() == now.YearDay():
-		return parsed.Format("15:04:05")
-	case parsed.Year() == now.Year():
-		return parsed.Format("Jan _2 15:04")
-	default:
-		return parsed.Format("2006-01-02")
-	}
-}
-
 // newSessionPicker builds the interactive /resume picker (mirrors /model & /provider):
-// one row per resumable session — title (Label) + id and relative age (Meta). Returns
-// nil when there are no resumable sessions so the caller falls back to the text path.
+// one row per resumable session — age + title (Label), session id (Value), and a
+// project/model/size line (Detail). Returns nil when there are no resumable
+// sessions so the caller falls back to the text path.
 func (m model) newSessionPicker() *commandPicker {
 	if m.sessionStore == nil {
 		return nil
@@ -414,13 +395,17 @@ func (m model) newSessionPicker() *commandPicker {
 		// Lead with a fixed-width timestamp so titles form one scannable column.
 		// The raw id remains the selection/search value but stays out of the row:
 		// rendering it consumed half the picker and truncated the useful title.
-		label := displayValue(meta.Title, "untitled")
-		if when := sessionWhen(meta.UpdatedAt, now); when != "" {
+		// Session metadata is persisted, user-controlled text — a title from
+		// --session-title or /rename can legally contain newlines, which would
+		// break the picker's fixed row geometry.
+		label := displayValue(sanitizeCardField(meta.Title), "untitled")
+		if when := relativeAge(meta.UpdatedAt, now); when != "" {
 			label = sessionPickerLabel(when, label)
 		}
 		items = append(items, pickerItem{
-			Label: label,
-			Value: meta.SessionID,
+			Label:  label,
+			Value:  meta.SessionID,
+			Detail: m.sessionPickerDetail(meta),
 		})
 	}
 	if len(items) == 0 {
@@ -435,12 +420,45 @@ func (m model) newSessionPicker() *commandPicker {
 	}
 }
 
-const sessionPickerTimeWidth = len("Jan 02 15:04")
+const sessionPickerTimeWidth = len("2006-01-02")
 
 func sessionPickerLabel(when, title string) string {
 	return fmt.Sprintf("%-*s  %s", sessionPickerTimeWidth, when, title)
 }
 
+// sessionPickerDetail composes the faint second line under a /resume row:
+// the session's project directory (~/-contracted), the model it ran on, and a
+// short status chip when the session is not a plain mainline run (forks,
+// tagged sessions such as btw side-chats). Missing fields are simply omitted —
+// the picker is workspace-scoped, so the project column is a confirmation,
+// not a disambiguator.
+func (m model) sessionPickerDetail(meta sessions.Metadata) string {
+	parts := make([]string, 0, 3)
+	if project := displayPath(m.cwd, meta.Cwd); project != "" {
+		parts = append(parts, project)
+	}
+	if modelID := strings.TrimSpace(meta.ModelID); modelID != "" {
+		parts = append(parts, modelID)
+	}
+	if status := sessionPickerStatus(meta); status != "" {
+		parts = append(parts, status)
+	}
+	return sanitizeCardField(strings.Join(parts, " · "))
+}
+
+// sessionPickerStatus is the concise status chip for a /resume row: an
+// explicit tag when the session carries one, otherwise a marker for forked
+// sessions. Plain mainline sessions get none — their shape is the default.
+func sessionPickerStatus(meta sessions.Metadata) string {
+	if tag := strings.TrimSpace(meta.Tag); tag != "" {
+		return tag
+	}
+	if meta.SessionKind == sessions.SessionKindFork {
+		return "fork"
+	}
+	return ""
+}
+
 // sessionHasResumableContent reports whether a session has anything worth
 // resuming: a tool call/result, or a non-user message with real content (not the
 // no-output guardrail stop). Empty/failed runs return false and are hidden from

internal/tui/session_test.go

@@ -9,6 +9,7 @@ import (
 	"sync/atomic"
 	"testing"
 	"time"
+	"unicode"
 
 	tea "charm.land/bubbletea/v2"
 
@@ -1249,3 +1250,188 @@ func assertPayloadFieldContains(t *testing.T, event sessions.Event, key string,
 		t.Fatalf("expected payload %s to contain %q, got %#v in %#v", key, want, payload[key], payload)
 	}
 }
+
+func TestRelativeAgeFormatsLastActivity(t *testing.T) {
+	now := time.Date(2026, 9, 12, 15, 0, 0, 0, time.UTC)
+	cases := []struct {
+		name string
+		ts   time.Time
+		want string
+	}{
+		{"just now", now.Add(-10 * time.Second), "now"},
+		{"slight clock skew", now.Add(30 * time.Second), "now"},
+		{"minutes", now.Add(-42 * time.Minute), "42m ago"},
+		{"hours", now.Add(-3 * time.Hour), "3h ago"},
+		{"days", now.Add(-12 * 24 * time.Hour), "12d ago"},
+		{"exactly one month", now.Add(-30 * 24 * time.Hour), "30d ago"},
+		{"this year", time.Date(2026, 1, 5, 9, 0, 0, 0, time.UTC), "Jan  5"},
+		{"last year", time.Date(2025, 6, 1, 0, 0, 0, 0, time.UTC), "2025-06-01"},
+	}
+	for _, tc := range cases {
+		if got := relativeAge(tc.ts.Format(time.RFC3339), now); got != tc.want {
+			t.Errorf("%s: sessionAge = %q, want %q", tc.name, got, tc.want)
+		}
+	}
+	if got := relativeAge("not-a-time", now); got != "" {
+		t.Errorf("unparseable timestamp = %q, want empty", got)
+	}
+	if got := relativeAge("", now); got != "" {
+		t.Errorf("empty timestamp = %q, want empty", got)
+	}
+}
+
+func TestSessionPickerDetailComposesProjectAndModel(t *testing.T) {
+	m := model{cwd: "/repo"}
+	detail := m.sessionPickerDetail(sessions.Metadata{
+		Title:   "work",
+		Cwd:     "/repo",
+		ModelID: "gpt-5",
+	})
+	for _, want := range []string{"/repo", "gpt-5"} {
+		if !strings.Contains(detail, want) {
+			t.Fatalf("detail %q missing %q", detail, want)
+		}
+	}
+	// Missing fields are omitted rather than rendered as empty segments.
+	if sparse := m.sessionPickerDetail(sessions.Metadata{Title: "bare"}); sparse != "" {
+		t.Fatalf("empty metadata should produce no detail line, got %q", sparse)
+	}
+}
+
+func TestSessionPickerDetailStatusChips(t *testing.T) {
+	m := model{}
+	if got := m.sessionPickerDetail(sessions.Metadata{SessionKind: sessions.SessionKindFork}); !strings.Contains(got, "fork") {
+		t.Fatalf("fork session detail %q should carry the fork chip", got)
+	}
+	if got := m.sessionPickerDetail(sessions.Metadata{Tag: "btw"}); !strings.Contains(got, "btw") {
+		t.Fatalf("tagged session detail %q should carry the tag", got)
+	}
+	if got := m.sessionPickerDetail(sessions.Metadata{Title: "plain"}); got != "" {
+		t.Fatalf("plain session detail %q should have no status chip", got)
+	}
+}
+
+func TestResumePickerDetailRendersOnlyAtMediumWidth(t *testing.T) {
+	store := testSessionStore(t)
+	sess, err := store.Create(sessions.CreateInput{Title: "Detail row", ModelID: "gpt-5-pickertest", Provider: "openai"})
+	if err != nil {
+		t.Fatalf("Create returned error: %v", err)
+	}
+	if _, err := store.AppendEvent(sess.SessionID, sessions.AppendEventInput{
+		Type:    sessions.EventMessage,
+		Payload: map[string]any{"role": "assistant", "content": "hi"},
+	}); err != nil {
+		t.Fatalf("AppendEvent returned error: %v", err)
+	}
+	m := newModel(context.Background(), Options{SessionStore: store})
+	m.input.SetValue("/resume")
+	updated, _ := m.Update(testKey(tea.KeyEnter))
+	next := updated.(model)
+	if next.picker == nil || next.picker.kind != pickerSession {
+		t.Fatalf("expected /resume to open the session picker, got %#v", next.picker)
+	}
+
+	next.width = 120
+	if wide := viewString(next.View()); !strings.Contains(wide, "gpt-5-pickertest") {
+		t.Fatalf("wide picker should render the detail line with the model:\n%s", wide)
+	}
+	next.width = 60
+	if narrow := viewString(next.View()); strings.Contains(narrow, "gpt-5-pickertest") {
+		t.Fatalf("narrow picker should keep the single-line fallback:\n%s", narrow)
+	}
+}
+
+func TestResumePickerFilterMatchesDetailFields(t *testing.T) {
+	store := testSessionStore(t)
+	mk := func(title, modelID string) {
+		sess, err := store.Create(sessions.CreateInput{Title: title, ModelID: modelID, Provider: "openai"})
+		if err != nil {
+			t.Fatalf("Create %q returned error: %v", title, err)
+		}
+		if _, err := store.AppendEvent(sess.SessionID, sessions.AppendEventInput{
+			Type:    sessions.EventMessage,
+			Payload: map[string]any{"role": "assistant", "content": "hi"},
+		}); err != nil {
+			t.Fatalf("AppendEvent %q returned error: %v", title, err)
+		}
+	}
+	mk("alpha", "gpt-5")
+	mk("beta", "claude-sonnet-4.5")
+
+	m := newModel(context.Background(), Options{SessionStore: store})
+	m.input.SetValue("/resume")
+	updated, _ := m.Update(testKey(tea.KeyEnter))
+	next := updated.(model)
+	if next.picker == nil {
+		t.Fatal("expected /resume to open the session picker")
+	}
+	// The model id lives only on the detail line; it must still filter rows.
+	next.picker.query = "claude-sonnet"
+	next.picker.applyQuery()
+	if len(next.picker.items) != 1 || !strings.Contains(next.picker.items[0].Label, "beta") {
+		t.Fatalf("filter by model should keep only the matching session, got %#v", next.picker.items)
+	}
+}
+
+func TestResumePickerSanitizesMultilineMetadata(t *testing.T) {
+	// Persisted session metadata is user-controlled: a title or model id can
+	// legally contain newlines, which must not break the picker's fixed
+	// one-or-two-line row geometry (a stray line shifts every row below it and
+	// misaligns mouse hit-testing).
+	store := testSessionStore(t)
+	sess, err := store.Create(sessions.CreateInput{
+		Title:   "alpha\nbravo",
+		ModelID: "gpt\x1b[31m5",
+		Cwd:     "/repo",
+		Tag:     "side\x1b]0;x\achat",
+	})
+	if err != nil {
+		t.Fatalf("Create returned error: %v", err)
+	}
+	if _, err := store.AppendEvent(sess.SessionID, sessions.AppendEventInput{
+		Type:    sessions.EventMessage,
+		Payload: map[string]any{"role": "assistant", "content": "hi"},
+	}); err != nil {
+		t.Fatalf("AppendEvent returned error: %v", err)
+	}
+	m := newModel(context.Background(), Options{SessionStore: store, Cwd: "/repo"})
+	m.input.SetValue("/resume")
+	updated, _ := m.Update(testKey(tea.KeyEnter))
+	next := updated.(model)
+	if next.picker == nil || len(next.picker.items) != 1 {
+		t.Fatalf("expected one picker item, got %#v", next.picker)
+	}
+	item := next.picker.items[0]
+	for _, r := range item.Label + item.Detail {
+		if unicode.IsControl(r) {
+			t.Fatalf("picker row leaked control rune %q: label=%q detail=%q", r, item.Label, item.Detail)
+		}
+	}
+}
+
+func TestGenericPickerMouseSelectsItemFromDetailLine(t *testing.T) {
+	m := mouseTestModel()
+	m.width = 120
+	m.picker = &commandPicker{
+		kind: pickerSession,
+		items: []pickerItem{
+			{Label: "one", Value: "s1", Detail: "meta one"},
+			{Label: "two", Value: "s2", Detail: "meta two"},
+		},
+	}
+	m.picker.allItems = append([]pickerItem{}, m.picker.items...)
+
+	width := chatWidth(m.width)
+	overlay := m.pickerOverlay(width)
+	rect := m.overlayMouseRect(len(viewLines(overlay)), width)
+	// Rows begin at y=3 inside the overlay; item 1's detail line is y=6.
+	// Click near the horizontal middle so the point lands inside the
+	// centered overlay block.
+	target, ok := m.selectGenericPickerAtMouse(testMouseClick(tea.MouseLeft, width/2, rect.y+6))
+	if !ok {
+		t.Fatal("click on a detail line should select its item")
+	}
+	if target.Value != "s2" {
+		t.Fatalf("detail-line click selected %q, want s2", target.Value)
+	}
+}

internal/tui/view.go

@@ -773,7 +773,7 @@ func (m model) pickerOverlay(width int) string {
 		overlayWidth = width
 	}
 	innerWidth := maxInt(1, overlayWidth-4)
-	maxVisible := minInt(pickerOverlayMaxVisible, len(m.picker.items))
+	maxVisible := pickerMaxVisible(m.picker, width)
 	start := 0
 	visible := []pickerItem{}
 	if len(m.picker.items) > 0 {
@@ -781,6 +781,7 @@ func (m model) pickerOverlay(width int) string {
 		start = selectableListStart(len(m.picker.items), maxVisible, m.picker.selected)
 		visible = m.picker.items[start : start+maxVisible]
 	}
+	showDetails := pickerShowsDetails(m.picker, width)
 
 	lines := make([]string, 0, len(visible)+7)
 	title := strings.TrimSpace(m.picker.title)
@@ -821,6 +822,16 @@ func (m model) pickerOverlay(width int) string {
 		gap := innerWidth - lipgloss.Width(left) - lipgloss.Width(right)
 		line := left + surface(zeroTheme.ink).Render(strings.Repeat(" ", maxInt(1, gap))) + right
 		lines = append(lines, fitStyledLine(line, innerWidth))
+		if showDetails && item.Detail != "" {
+			// The detail line sits under the row on the same selection band,
+			// indented to the label column so it reads as part of the item.
+			// Pad the remainder like the row above so the band is full-width.
+			detailText := "  " + item.Detail
+			detailGap := innerWidth - lipgloss.Width(detailText)
+			detail := surface(zeroTheme.faint).Render(detailText) +
+				surface(zeroTheme.faint).Render(strings.Repeat(" ", maxInt(0, detailGap)))
+			lines = append(lines, fitStyledLine(detail, innerWidth))
+		}
 	}
 	if len(visible) == 0 {
 		if m.picker.loading {
@@ -845,6 +856,36 @@ func (m model) pickerOverlay(width int) string {
 	return centerRenderedBlock(styledBlockFillTitle(overlayWidth, title, lines, zeroTheme.lineStrong, lipgloss.NewStyle()), width)
 }
 
+// pickerShowsDetails reports whether the overlay renders each row's optional
+// Detail line: only when a row actually carries one and the terminal is at
+// least medium width, where the two-line treatment reads cleanly. Narrower
+// tiers keep the single-line list fallback.
+func pickerShowsDetails(p *commandPicker, width int) bool {
+	if p == nil || widthTier(width) < tierMedium {
+		return false
+	}
+	for _, item := range p.items {
+		if item.Detail != "" {
+			return true
+		}
+	}
+	return false
+}
+
+// pickerMaxVisible caps the visible window in items. When detail lines render,
+// each item costs two rows, so the budget halves to keep the overlay the same
+// height as the single-line list.
+func pickerMaxVisible(p *commandPicker, width int) int {
+	if p == nil {
+		return 0
+	}
+	budget := pickerOverlayMaxVisible
+	if pickerShowsDetails(p, width) {
+		budget = pickerOverlayMaxVisible / 2
+	}
+	return minInt(budget, len(p.items))
+}
+
 // themePickerOverlay keeps candidate rendering inside the picker. Moving through
 // themes therefore shows their hierarchy and code treatment without repainting the
 // transcript, terminal canvas, or any other active UI.