Trim eager read tool schemas

internal/agent/compaction.go

@@ -38,9 +38,8 @@ const compactionTriggerRatio = 0.7
 // transcript (and so tests can assert on it).
 const summaryLabel = "[Summary of earlier conversation]"
 
-// CompactionSummaryInstructions is the system prompt handed to both automatic
-// and manually requested compaction summarizers.
-const CompactionSummaryInstructions = "You are compacting a coding-assistant conversation to save context. " +
+// summaryInstructions is the system prompt handed to the summarizer model.
+const summaryInstructions = "You are compacting a coding-assistant conversation to save context. " +
 	"Write a dense, factual summary of the conversation so far. Preserve: the user's goals and explicit constraints; " +
 	"decisions made and why; files created or modified (with paths) and key code changes; commands run and their important " +
 	"results; and anything still in progress or unresolved. Omit pleasantries. Use terse bullet points. Do not invent details. " +
@@ -76,12 +75,6 @@ type CompactionResult struct {
 	// summary message also includes summaryLabel and any preserved structured
 	// state needed by later compactions.
 	SummaryText string
-	// ProjectedChars is the text content sent to the summarizer after semantic
-	// projection, excluding provider protocol framing.
-	ProjectedChars int
-	// Truncated reports whether projection dropped content to satisfy its
-	// bounded brief or previous-summary limits.
-	Truncated bool
 	// Compacted reports whether Messages contains an injected summary.
 	Compacted bool
 }
@@ -223,11 +216,11 @@ func CompactMessages(messages []zeroruntime.Message, opts CompactionOptions) (Co
 		}, nil
 	}
 
-	summaryResult, err := SummarizeCompactionMessages(middle, opts.Summarize)
+	summary, err := opts.Summarize(middle)
 	if err != nil {
 		return CompactionResult{}, err
 	}
-	summary := summaryResult.SummaryText
+	summary = strings.TrimSpace(summary)
 
 	// Preserve structured state (active plan + loaded skills) from the elided
 	// middle verbatim, so it is not lost or paraphrased away by the prose summary.
@@ -245,53 +238,10 @@ func CompactMessages(messages []zeroruntime.Message, opts CompactionOptions) (Co
 		RemovedCount:   len(middle),
 		PreservedCount: len(messages) - len(middle),
 		SummaryText:    summary,
-		ProjectedChars: summaryResult.ProjectedChars,
-		Truncated:      summaryResult.Truncated,
 		Compacted:      true,
 	}, nil
 }
 
-// CompactionSummaryResult describes the shared summarization input and output.
-type CompactionSummaryResult struct {
-	SummaryText    string
-	ProjectedChars int
-	Truncated      bool
-}
-
-// SummarizeCompactionMessages applies the shared semantic projection before
-// invoking a caller-supplied summarizer. Automatic context-pressure compaction
-// and manual session compaction both use this path.
-func SummarizeCompactionMessages(messages []zeroruntime.Message, summarize func([]zeroruntime.Message) (string, error)) (CompactionSummaryResult, error) {
-	if summarize == nil {
-		return CompactionSummaryResult{}, errors.New("compaction requires a Summarize function")
-	}
-	projection := projectCompactionInput(messages)
-	summaryInput := projection.messages
-	if len(summaryInput) == 0 {
-		summaryInput = messages
-	}
-	summary, err := summarize(summaryInput)
-	if err != nil {
-		return CompactionSummaryResult{}, err
-	}
-	return CompactionSummaryResult{
-		SummaryText:    strings.TrimSpace(summary),
-		ProjectedChars: compactionMessageChars(summaryInput),
-		Truncated:      projection.truncated,
-	}, nil
-}
-
-func compactionMessageChars(messages []zeroruntime.Message) int {
-	total := 0
-	for _, message := range messages {
-		total += len(message.Content)
-		for _, call := range message.ToolCalls {
-			total += len(call.Name) + len(call.Arguments)
-		}
-	}
-	return total
-}
-
 // safeSuffixBoundary walks the preserve boundary backward (toward systemEnd) so
 // the preserved suffix begins on a user or assistant message rather than a
 // tool/tool_result message. A tool result with no preceding assistant tool call
@@ -626,7 +576,7 @@ func summarizeWithFallback(ctx context.Context, provider Provider, messages []ze
 func summarizeMessagesOnce(ctx context.Context, provider Provider, messages []zeroruntime.Message, onUsage func(Usage)) (string, error) {
 	request := zeroruntime.CompletionRequest{
 		Messages: []zeroruntime.Message{
-			{Role: zeroruntime.MessageRoleSystem, Content: CompactionSummaryInstructions},
+			{Role: zeroruntime.MessageRoleSystem, Content: summaryInstructions},
 			{Role: zeroruntime.MessageRoleUser, Content: "Summarize this conversation:\n\n" + renderTranscript(messages)},
 		},
 		// No tools: this is a plain text summarization call.

internal/agent/compaction_metadata_test.go

@@ -43,14 +43,8 @@ func TestCompactMessagesReturnsMetadataForManualCompaction(t *testing.T) {
 	if result.SummaryText != "manual summary" {
 		t.Fatalf("SummaryText = %q, want trimmed summary", result.SummaryText)
 	}
-	if result.ProjectedChars != compactionMessageChars(captured) || result.ProjectedChars == 0 {
-		t.Fatalf("ProjectedChars = %d, want %d", result.ProjectedChars, compactionMessageChars(captured))
-	}
-	if result.Truncated {
-		t.Fatal("Truncated = true for a projection within its limits")
-	}
-	if len(captured) != 1 || !strings.Contains(captured[0].Content, "first question") || !strings.Contains(captured[0].Content, "second question") {
-		t.Fatalf("summarized projection = %#v, want intent from the non-preserved middle", captured)
+	if len(captured) != 3 || captured[0].Content != "first question" || captured[2].Content != "second question" {
+		t.Fatalf("summarized middle = %#v, want the three non-preserved non-system messages", captured)
 	}
 	if len(result.Messages) != 4 {
 		t.Fatalf("compacted message count = %d, want 4", len(result.Messages))
@@ -102,46 +96,11 @@ func TestCompactMessagesNoopReturnsUncompactedMetadata(t *testing.T) {
 	if result.SummaryText != "" {
 		t.Fatalf("SummaryText = %q, want empty", result.SummaryText)
 	}
-	if result.ProjectedChars != 0 || result.Truncated {
-		t.Fatalf("no-op projection metadata = (%d, %t), want zero values", result.ProjectedChars, result.Truncated)
-	}
 	if !reflect.DeepEqual(result.Messages, messages) {
 		t.Fatalf("Messages changed on no-op: %#v", result.Messages)
 	}
 }
 
-func TestCompactMessagesReturnsTruncatedProjectionMetadata(t *testing.T) {
-	messages := []zeroruntime.Message{{Role: zeroruntime.MessageRoleSystem, Content: "system"}}
-	for index := range 20 {
-		messages = append(messages, zeroruntime.Message{
-			Role:    zeroruntime.MessageRoleUser,
-			Content: strings.Repeat("contextword ", 256) + string(rune('a'+index)),
-		})
-	}
-	messages = append(messages,
-		zeroruntime.Message{Role: zeroruntime.MessageRoleAssistant, Content: "recent answer"},
-		zeroruntime.Message{Role: zeroruntime.MessageRoleUser, Content: "latest question"},
-	)
-
-	var captured []zeroruntime.Message
-	result, err := CompactMessages(messages, CompactionOptions{
-		PreserveLast: 2,
-		Summarize: func(toSummarize []zeroruntime.Message) (string, error) {
-			captured = append([]zeroruntime.Message(nil), toSummarize...)
-			return "bounded summary", nil
-		},
-	})
-	if err != nil {
-		t.Fatal(err)
-	}
-	if !result.Compacted || !result.Truncated {
-		t.Fatalf("compaction metadata = compacted %t, truncated %t; want both true", result.Compacted, result.Truncated)
-	}
-	if result.ProjectedChars != compactionMessageChars(captured) || result.ProjectedChars == 0 {
-		t.Fatalf("ProjectedChars = %d, want %d", result.ProjectedChars, compactionMessageChars(captured))
-	}
-}
-
 func TestCompactMessagesPropagatesSummarizeError(t *testing.T) {
 	messages := []zeroruntime.Message{
 		{Role: zeroruntime.MessageRoleSystem, Content: "system"},

internal/agent/compaction_preserve.go

@@ -102,7 +102,7 @@ type skillEntry struct {
 	body string
 }
 
-// recentEdits returns files mutated by editing calls in messages
+// recentEdits returns the files mutated by write_file/edit_file calls in messages
 // — latest note per path, in last-seen order — as skillEntry{name: path, body:
 // note}. After compaction elides the editing turns, this tells the model WHAT it
 // changed in each file (from the tool's result) so it need not re-read to
@@ -113,7 +113,6 @@ type skillEntry struct {
 // rather than an earlier, now-stale entry.
 func recentEdits(messages []zeroruntime.Message) []skillEntry {
 	pathByID := map[string]string{}
-	noteByPath := map[string]string{}
 	sequence := make([]string, 0)
 	for _, message := range messages {
 		for _, call := range message.ToolCalls {
@@ -130,24 +129,12 @@ func recentEdits(messages []zeroruntime.Message) []skillEntry {
 			sequence = append(sequence, path)
 		}
 	}
-	for _, message := range messages {
-		if message.Role != zeroruntime.MessageRoleTool || len(message.ChangedFiles) == 0 {
-			continue
-		}
-		for _, path := range message.ChangedFiles {
-			path = strings.TrimSpace(path)
-			if path == "" {
-				continue
-			}
-			sequence = append(sequence, path)
-			noteByPath[path] = editNote(message.Content)
-		}
-	}
 	order := lastSeenOrder(sequence)
 	if len(order) == 0 {
 		return nil
 	}
 
+	noteByPath := map[string]string{}
 	for _, message := range messages {
 		if message.Role != zeroruntime.MessageRoleTool || message.ToolCallID == "" {
 			continue
@@ -438,20 +425,15 @@ type preservedState struct {
 }
 
 type preservedTaskState struct {
-	Objective           string              `json:"objective"`
-	Status              taskStatus          `json:"status,omitempty"`
-	Pending             int                 `json:"pending,omitempty"`
-	InProgress          int                 `json:"in_progress,omitempty"`
-	Completed           int                 `json:"completed,omitempty"`
-	Failed              int                 `json:"failed,omitempty"`
-	VerificationPassed  int                 `json:"verification_passed,omitempty"`
-	VerificationFailed  int                 `json:"verification_failed,omitempty"`
-	VerificationOutcome Outcome             `json:"verification_outcome,omitempty"`
-	Constraints         []string            `json:"constraints,omitempty"`
-	ChangedFiles        []string            `json:"changed_files,omitempty"`
-	UnresolvedFailures  []taskFailureState  `json:"unresolved_failures,omitempty"`
-	Approvals           []taskApprovalState `json:"approvals,omitempty"`
-	Artifacts           []taskArtifactState `json:"artifacts,omitempty"`
+	Objective           string     `json:"objective"`
+	Status              taskStatus `json:"status,omitempty"`
+	Pending             int        `json:"pending,omitempty"`
+	InProgress          int        `json:"in_progress,omitempty"`
+	Completed           int        `json:"completed,omitempty"`
+	Failed              int        `json:"failed,omitempty"`
+	VerificationPassed  int        `json:"verification_passed,omitempty"`
+	VerificationFailed  int        `json:"verification_failed,omitempty"`
+	VerificationOutcome Outcome    `json:"verification_outcome,omitempty"`
 }
 
 type preservedEdit struct {
@@ -486,12 +468,7 @@ func appendPreservedState(summary string, middle []zeroruntime.Message, taskSnap
 	task := priorState.Task
 	if taskSnapshot != nil {
 		task = &preservedTaskState{
-			Objective:          capTaskObjective(taskSnapshot.Objective),
-			Constraints:        mergeBoundedComparable(priorTaskConstraints(priorState.Task), taskSnapshot.Constraints, maxTaskConstraints),
-			ChangedFiles:       mergeBoundedComparable(priorTaskChangedFiles(priorState.Task), taskSnapshot.ChangedFiles, maxTaskEvidenceEntries),
-			UnresolvedFailures: mergeTaskFailures(priorTaskFailures(priorState.Task), taskSnapshot.UnresolvedFailures, taskSnapshot.ResolvedFailureKeys),
-			Approvals:          mergeBoundedComparable(priorTaskApprovals(priorState.Task), taskSnapshot.Approvals, maxTaskEvidenceEntries),
-			Artifacts:          mergeBoundedComparable(priorTaskArtifacts(priorState.Task), taskSnapshot.Artifacts, maxTaskEvidenceEntries),
+			Objective: capTaskObjective(taskSnapshot.Objective),
 		}
 		// Plan parity corroborates only the mutable task projection. The objective
 		// comes directly from the run prompt and is immutable, so it must survive
@@ -507,13 +484,6 @@ func appendPreservedState(summary string, middle []zeroruntime.Message, taskSnap
 			task.VerificationOutcome = taskSnapshot.Verification.LastOutcome
 		}
 	}
-	freshConstraints := explicitConstraintsFromMessages(middle)
-	if len(freshConstraints) > 0 {
-		if task == nil {
-			task = &preservedTaskState{}
-		}
-		task.Constraints = mergeBoundedComparable(task.Constraints, freshConstraints, maxTaskConstraints)
-	}
 
 	// Plan: a fresh update_plan in middle is authoritative; otherwise carry the
 	// plan preserved by an earlier compaction.
@@ -547,95 +517,6 @@ func appendPreservedState(summary string, middle []zeroruntime.Message, taskSnap
 	return summary
 }
 
-func explicitConstraintsFromMessages(messages []zeroruntime.Message) []string {
-	var constraints []string
-	for _, message := range messages {
-		if message.Role != zeroruntime.MessageRoleUser || strings.Contains(message.Content, preservedStateLabel) {
-			continue
-		}
-		if _, body := projectInstructionBlock(message.Content); body != "" {
-			continue
-		}
-		constraints = mergeBoundedComparable(constraints, extractExplicitConstraints(message.Content), maxTaskConstraints)
-	}
-	return constraints
-}
-
-func priorTaskConstraints(task *preservedTaskState) []string {
-	if task == nil {
-		return nil
-	}
-	return task.Constraints
-}
-
-func priorTaskChangedFiles(task *preservedTaskState) []string {
-	if task == nil {
-		return nil
-	}
-	return task.ChangedFiles
-}
-
-func priorTaskFailures(task *preservedTaskState) []taskFailureState {
-	if task == nil {
-		return nil
-	}
-	return task.UnresolvedFailures
-}
-
-func priorTaskApprovals(task *preservedTaskState) []taskApprovalState {
-	if task == nil {
-		return nil
-	}
-	return task.Approvals
-}
-
-func priorTaskArtifacts(task *preservedTaskState) []taskArtifactState {
-	if task == nil {
-		return nil
-	}
-	return task.Artifacts
-}
-
-func mergeTaskFailures(older, newer []taskFailureState, resolved []string) []taskFailureState {
-	resolvedSet := make(map[string]struct{}, len(resolved))
-	for _, key := range resolved {
-		resolvedSet[key] = struct{}{}
-	}
-	merged := make([]taskFailureState, 0, len(older)+len(newer))
-	for _, failure := range append(append([]taskFailureState(nil), older...), newer...) {
-		if _, ok := resolvedSet[failure.Key]; ok {
-			continue
-		}
-		withoutSameKey := make([]taskFailureState, 0, len(merged))
-		for _, existing := range merged {
-			if existing.Key != failure.Key {
-				withoutSameKey = append(withoutSameKey, existing)
-			}
-		}
-		merged = append(withoutSameKey, failure)
-	}
-	if len(merged) > maxTaskEvidenceEntries {
-		merged = merged[len(merged)-maxTaskEvidenceEntries:]
-	}
-	return merged
-}
-
-func mergeBoundedComparable[T comparable](older, newer []T, limit int) []T {
-	merged := make([]T, 0, len(older)+len(newer))
-	seen := make(map[T]struct{}, len(older)+len(newer))
-	for _, value := range append(append([]T(nil), older...), newer...) {
-		if _, ok := seen[value]; ok {
-			continue
-		}
-		seen[value] = struct{}{}
-		merged = append(merged, value)
-	}
-	if len(merged) > limit {
-		merged = merged[len(merged)-limit:]
-	}
-	return merged
-}
-
 func capTaskObjective(objective string) string {
 	objective = strings.TrimSpace(objective)
 	if len(objective) <= maxTaskObjectiveBytes {

internal/agent/compaction_preserve_test.go

@@ -6,7 +6,6 @@ import (
 	"testing"
 	"unicode/utf8"
 
-	"github.com/Gitlawb/zero/internal/tools"
 	"github.com/Gitlawb/zero/internal/zeroruntime"
 )
 
@@ -65,9 +64,6 @@ func TestCompactPreservesBoundedTaskContext(t *testing.T) {
 	objective := strings.Repeat("世", maxTaskObjectiveBytes)
 	task := newTaskState(objective, nil)
 	task.observe(taskStateEvent{kind: taskStateEventPlan, arguments: `{"plan":[{"content":"write code","status":"in_progress"},{"content":"add tests","status":"pending"}]}`})
-	task.observe(taskStateEvent{kind: taskStateEventToolResult, arguments: `{"patch":"*** Update File: internal/db.go"}`, toolResult: ToolResult{
-		Name: "apply_patch", Status: tools.StatusOK, Output: "Done!", ChangedFiles: []string{"internal/db.go"},
-	}})
 	messages := stateConversation()
 	compacted, err := Compact(messages, CompactionOptions{
 		PreserveLast: 2,
@@ -84,69 +80,6 @@ func TestCompactPreservesBoundedTaskContext(t *testing.T) {
 	if len(state.Task.Objective) > maxTaskObjectiveBytes || !utf8.ValidString(state.Task.Objective) {
 		t.Fatalf("objective was not safely bounded: %d bytes %q", len(state.Task.Objective), state.Task.Objective)
 	}
-	if len(state.Task.ChangedFiles) != 1 || state.Task.ChangedFiles[0] != "internal/db.go" {
-		t.Fatalf("changed files were not preserved: %#v", state.Task.ChangedFiles)
-	}
-}
-
-func TestCompactPreservesRuntimeEvidenceAcrossRepeatedCompaction(t *testing.T) {
-	task := newTaskState("Please keep the change focused.", nil)
-	task.observe(taskStateEvent{kind: taskStateEventToolResult, arguments: `{"cmd":"go test ./..."}`, toolResult: ToolResult{
-		Name: "exec_command", Status: tools.StatusError, Output: "Error: tests failed",
-		Meta: map[string]string{"spill_path": ".zero/artifacts/tests.txt"},
-	}})
-	task.observe(taskStateEvent{kind: taskStateEventPermission, permission: PermissionEvent{
-		ToolName: "exec_command", DecisionAction: PermissionDecisionAllowForSession, Scope: "/tmp",
-	}})
-	messages := stateConversation()
-
-	first, err := Compact(messages, CompactionOptions{
-		PreserveLast: 2,
-		Summarize:    func([]zeroruntime.Message) (string, error) { return "FIRST", nil },
-		taskState:    task.snapshotForCompaction(messages),
-	})
-	if err != nil {
-		t.Fatal(err)
-	}
-	task.observe(taskStateEvent{kind: taskStateEventToolResult, arguments: `{"cmd":"go test ./..."}`, toolResult: ToolResult{
-		Name: "exec_command", Status: tools.StatusError, Output: "Error: tests still fail with newer evidence",
-		Meta: map[string]string{"spill_path": ".zero/artifacts/tests.txt"},
-	}})
-	secondInput := append(append([]zeroruntime.Message{}, first...),
-		zeroruntime.Message{Role: zeroruntime.MessageRoleUser, Content: "Never add background memory models."},
-		zeroruntime.Message{Role: zeroruntime.MessageRoleAssistant, Content: "understood"},
-		zeroruntime.Message{Role: zeroruntime.MessageRoleUser, Content: "continue"},
-		zeroruntime.Message{Role: zeroruntime.MessageRoleAssistant, Content: "working"},
-	)
-	second, err := Compact(secondInput, CompactionOptions{
-		PreserveLast: 2,
-		Summarize:    func([]zeroruntime.Message) (string, error) { return "SECOND", nil },
-		taskState:    task.snapshotForCompaction(secondInput),
-	})
-	if err != nil {
-		t.Fatal(err)
-	}
-	state := parsePreservedStateBlock(second[1].Content)
-	if state.Task == nil || len(state.Task.UnresolvedFailures) != 1 || len(state.Task.Approvals) != 1 || len(state.Task.Artifacts) != 1 {
-		t.Fatalf("runtime evidence did not survive repeated compaction: %#v", state.Task)
-	}
-	if got := state.Task.UnresolvedFailures[0].Summary; got != "Error: tests still fail with newer evidence" {
-		t.Fatalf("newer failure evidence did not replace the older summary: %#v", state.Task.UnresolvedFailures)
-	}
-	for _, want := range []string{"Please keep the change focused.", "Never add background memory models."} {
-		if !containsString(state.Task.Constraints, want) {
-			t.Fatalf("constraint %q missing after repeated compaction: %#v", want, state.Task.Constraints)
-		}
-	}
-}
-
-func containsString(values []string, want string) bool {
-	for _, value := range values {
-		if value == want {
-			return true
-		}
-	}
-	return false
 }
 
 func TestCompactPreservesObjectiveAfterPlanParityMismatch(t *testing.T) {

internal/agent/compaction_projection.go

@@ -1,315 +0,0 @@
-package agent
-
-import (
-	"encoding/json"
-	"fmt"
-	"regexp"
-	"strings"
-
-	"github.com/Gitlawb/zero/internal/zeroruntime"
-)
-
-const (
-	compactionUserWordBudget       = 256
-	compactionAssistantWordBudget  = 200
-	compactionToolCallsPerTurn     = 8
-	compactionToolArgumentBytes    = 120
-	compactionErrorBytes           = 150
-	compactionResultBytes          = 1200
-	compactionPreviousSummaryBytes = 16 * 1024
-	compactionBriefMaxBytes        = 24 * 1024
-)
-
-var compactionWordPattern = regexp.MustCompile(`[\p{L}\p{N}]+`)
-
-type compactionProjection struct {
-	messages  []zeroruntime.Message
-	truncated bool
-}
-
-// projectCompactionInput removes reconstructible tool output before the model
-// summary call. It retains a bounded transcript of user intent, assistant
-// decisions, tool actions, and concise errors. Exact durable state is appended
-// separately from the original messages after the summary returns.
-func projectCompactionInput(messages []zeroruntime.Message) compactionProjection {
-	sections := make([]string, 0, len(messages))
-	previousSummary := ""
-	truncated := false
-	for index, message := range messages {
-		switch message.Role {
-		case zeroruntime.MessageRoleUser:
-			content := message.Content
-			if marker := strings.Index(content, preservedStateLabel); marker >= 0 {
-				content = content[:marker]
-			}
-			trimmed := strings.TrimSpace(content)
-			if strings.HasPrefix(trimmed, summaryLabel) {
-				fullSummary := strings.TrimSpace(strings.TrimPrefix(trimmed, summaryLabel))
-				previousSummary = clipHeadTailBytes(fullSummary, compactionPreviousSummaryBytes)
-				truncated = truncated || len(fullSummary) > compactionPreviousSummaryBytes
-				continue
-			}
-			if content = clipInformativeWords(content, compactionUserWordBudget); content != "" {
-				sections = append(sections, fmt.Sprintf("[user #%d]\n%s", index, content))
-			}
-		case zeroruntime.MessageRoleAssistant:
-			lines := make([]string, 0, 1+len(message.ToolCalls))
-			if content := clipInformativeWords(message.Content, compactionAssistantWordBudget); content != "" {
-				lines = append(lines, content)
-			}
-			calls := message.ToolCalls
-			omitted := 0
-			if len(calls) > compactionToolCallsPerTurn {
-				omitted = len(calls) - compactionToolCallsPerTurn
-				calls = calls[omitted:]
-			}
-			if omitted > 0 {
-				lines = append(lines, fmt.Sprintf("* (%d earlier tool calls omitted)", omitted))
-			}
-			for _, call := range calls {
-				lines = append(lines, compactionToolCallLine(call))
-			}
-			if len(lines) > 0 {
-				sections = append(sections, fmt.Sprintf("[assistant #%d]\n%s", index, strings.Join(lines, "\n")))
-			}
-		case zeroruntime.MessageRoleTool:
-			// New tool-result messages carry the execution status directly, as the
-			// source ToolResult does. Keep the text check for older session history
-			// created before Message exposed IsError.
-			name := toolNameForResult(messages, index)
-			mustPreserve := name == "ask_user" || len(message.ChangedFiles) > 0
-			if !mustPreserve && !message.IsError && !isLikelyToolError(message.Content) {
-				continue
-			}
-			if name == "" {
-				name = "tool"
-			}
-			switch {
-			case message.IsError || isLikelyToolError(message.Content):
-				sections = append(sections, fmt.Sprintf("[tool_error #%d] %s\n%s", index, name, clipBytes(firstLine(message.Content), compactionErrorBytes)))
-			case name == "ask_user":
-				sections = append(sections, fmt.Sprintf("[user_answer #%d] %s\n%s", index, name, clipBytes(message.Content, compactionResultBytes)))
-			default:
-				sections = append(sections, fmt.Sprintf("[tool_result #%d] %s changed %s\n%s", index, name,
-					clipBytes(strings.Join(message.ChangedFiles, ", "), compactionToolArgumentBytes), clipBytes(firstLine(message.Content), compactionErrorBytes)))
-			}
-		}
-	}
-	if len(sections) == 0 && previousSummary == "" {
-		return compactionProjection{}
-	}
-	brief, briefTruncated := capCompactionBrief(strings.Join(sections, "\n\n"))
-	truncated = truncated || briefTruncated
-	if previousSummary != "" {
-		brief = "[previous summary]\n" + previousSummary + "\n\n" + brief
-	}
-	return compactionProjection{
-		messages:  []zeroruntime.Message{{Role: zeroruntime.MessageRoleUser, Content: strings.TrimSpace(brief)}},
-		truncated: truncated,
-	}
-}
-
-func capCompactionBrief(brief string) (string, bool) {
-	if len(brief) <= compactionBriefMaxBytes {
-		return brief, false
-	}
-	marker := "\n\n...[middle transcript omitted to fit compaction budget]...\n\n"
-	available := compactionBriefMaxBytes - len(marker)
-	// Keep both chronological edges: the oldest material has not necessarily
-	// been summarized before, while the newest material is most actionable.
-	headBytes := available * 2 / 5
-	tailBytes := available - headBytes
-	head := clipPrefixAtBoundary(brief, headBytes)
-	tail := clipSuffixAtBoundary(brief, tailBytes)
-	return strings.TrimSpace(head) + marker + strings.TrimSpace(tail), true
-}
-
-func compactionToolCallLine(call zeroruntime.ToolCall) string {
-	detail := ""
-	var arguments map[string]any
-	if json.Unmarshal([]byte(strings.TrimSpace(call.Arguments)), &arguments) == nil {
-		for _, key := range []string{"file_path", "path", "url", "query", "pattern", "prompt", "description", "question"} {
-			if value, ok := arguments[key].(string); ok && strings.TrimSpace(value) != "" {
-				detail = value
-				break
-			}
-		}
-		if detail == "" && call.Name == "ask_user" {
-			detail = askUserQuestionsDetail(arguments)
-		}
-		if detail == "" && call.Name == "apply_patch" {
-			if patch, ok := arguments["patch"].(string); ok {
-				detail = strings.Join(patchPaths(patch), ", ")
-			}
-		}
-	}
-	if detail == "" {
-		detail = commandFromArguments(call.Arguments)
-	}
-	if detail == "" {
-		return "* " + call.Name
-	}
-	return fmt.Sprintf("* %s %q", call.Name, clipBytes(detail, compactionToolArgumentBytes))
-}
-
-func isLikelyToolError(content string) bool {
-	prefix := strings.TrimSpace(content)
-	if len(prefix) > compactionErrorBytes {
-		prefix = prefix[:compactionErrorBytes]
-	}
-	lower := strings.ToLower(prefix)
-	for _, prefix := range []string{"error:", "tool error:", "failed:", "permission denied", "command failed"} {
-		if strings.HasPrefix(lower, prefix) {
-			return true
-		}
-	}
-	return false
-}
-
-func clipInformativeWords(text string, limit int) string {
-	flat := strings.Join(strings.Fields(text), " ")
-	if flat == "" || limit <= 0 {
-		return ""
-	}
-	count := 0
-	for _, location := range compactionWordPattern.FindAllStringIndex(flat, -1) {
-		word := strings.ToLower(flat[location[0]:location[1]])
-		if compactionStopWords[word] {
-			continue
-		}
-		count++
-		if count > limit {
-			end := location[0]
-			return strings.TrimSpace(flat[:end]) + "...(truncated)"
-		}
-	}
-	return flat
-}
-
-func clipBytes(text string, limit int) string {
-	text = strings.TrimSpace(text)
-	if limit <= 0 {
-		return ""
-	}
-	if len(text) <= limit {
-		return text
-	}
-	if limit <= 3 {
-		end := limit
-		for end > 0 && end < len(text) && text[end]&0xc0 == 0x80 {
-			end--
-		}
-		return text[:end]
-	}
-	end := limit - 3
-	for end > 0 && end < len(text) && text[end]&0xc0 == 0x80 {
-		end--
-	}
-	return strings.TrimSpace(text[:end]) + "..."
-}
-
-func clipHeadTailBytes(text string, limit int) string {
-	text = strings.TrimSpace(text)
-	if len(text) <= limit {
-		return text
-	}
-	if limit <= 0 {
-		return ""
-	}
-	marker := "\n...[middle omitted]...\n"
-	if limit <= len(marker) {
-		return clipBytes(text, limit)
-	}
-	available := limit - len(marker)
-	head := clipPrefixAtBoundary(text, available/2)
-	tail := clipSuffixAtBoundary(text, available-available/2)
-	return strings.TrimSpace(head) + marker + strings.TrimSpace(tail)
-}
-
-func clipPrefixAtBoundary(text string, limit int) string {
-	if limit <= 0 {
-		return ""
-	}
-	if len(text) <= limit {
-		return text
-	}
-	end := limit
-	for end > 0 && text[end]&0xc0 == 0x80 {
-		end--
-	}
-	if boundary := strings.LastIndex(text[:end], "\n\n["); boundary > 0 {
-		end = boundary
-	}
-	return text[:end]
-}
-
-func clipSuffixAtBoundary(text string, limit int) string {
-	if limit <= 0 {
-		return ""
-	}
-	if len(text) <= limit {
-		return text
-	}
-	start := len(text) - limit
-	for start < len(text) && text[start]&0xc0 == 0x80 {
-		start++
-	}
-	if boundary := strings.Index(text[start:], "\n\n["); boundary >= 0 {
-		start += boundary + 2
-	}
-	return text[start:]
-}
-
-func askUserQuestionsDetail(arguments map[string]any) string {
-	raw, ok := arguments["questions"].([]any)
-	if !ok {
-		return ""
-	}
-	questions := make([]string, 0, len(raw))
-	for _, item := range raw {
-		object, ok := item.(map[string]any)
-		if !ok {
-			continue
-		}
-		if question, ok := object["question"].(string); ok && strings.TrimSpace(question) != "" {
-			questions = append(questions, strings.TrimSpace(question))
-		}
-	}
-	return strings.Join(questions, " | ")
-}
-
-func patchPaths(patch string) []string {
-	var paths []string
-	seen := map[string]bool{}
-	for _, line := range strings.Split(patch, "\n") {
-		for _, prefix := range []string{"*** Add File: ", "*** Update File: ", "*** Delete File: ", "*** Move to: "} {
-			if !strings.HasPrefix(line, prefix) {
-				continue
-			}
-			path := strings.TrimSpace(strings.TrimPrefix(line, prefix))
-			if path != "" && !seen[path] {
-				seen[path] = true
-				paths = append(paths, path)
-			}
-		}
-	}
-	return paths
-}
-
-var compactionStopWords = map[string]bool{
-	"a": true, "an": true, "the": true, "is": true, "are": true, "was": true, "were": true,
-	"be": true, "been": true, "being": true, "have": true, "has": true, "had": true,
-	"do": true, "does": true, "did": true, "will": true, "would": true, "could": true,
-	"should": true, "may": true, "might": true, "shall": true, "can": true, "need": true, "must": true,
-	"to": true, "of": true, "in": true, "for": true, "on": true, "with": true, "at": true,
-	"by": true, "from": true, "as": true, "into": true, "through": true, "during": true,
-	"before": true, "after": true, "above": true, "below": true, "between": true, "under": true, "over": true,
-	"and": true, "but": true, "or": true, "nor": true, "not": true, "so": true, "yet": true,
-	"both": true, "either": true, "neither": true, "each": true, "every": true, "all": true,
-	"any": true, "few": true, "more": true, "most": true, "other": true, "some": true, "such": true, "no": true,
-	"that": true, "this": true, "these": true, "those": true, "it": true, "its": true,
-	"i": true, "me": true, "my": true, "we": true, "our": true, "you": true, "your": true,
-	"he": true, "him": true, "his": true, "she": true, "her": true, "they": true, "them": true, "their": true,
-	"who": true, "which": true, "what": true, "if": true, "then": true, "than": true,
-	"when": true, "where": true, "how": true, "just": true, "also": true,
-}

internal/agent/compaction_projection_test.go

@@ -1,130 +0,0 @@
-package agent
-
-import (
-	"strings"
-	"testing"
-	"unicode/utf8"
-
-	"github.com/Gitlawb/zero/internal/zeroruntime"
-)
-
-func TestClipBytesHandlesTinyLimitsOnRuneBoundaries(t *testing.T) {
-	for _, limit := range []int{0, 1, 2, 3} {
-		if clipped := clipBytes("世界", limit); len(clipped) > limit || !utf8.ValidString(clipped) {
-			t.Fatalf("clipBytes limit %d returned invalid result %q", limit, clipped)
-		}
-	}
-}
-
-func TestBoundaryClippersHandleNonPositiveLimits(t *testing.T) {
-	for _, clip := range []func(string, int) string{clipPrefixAtBoundary, clipSuffixAtBoundary} {
-		for _, limit := range []int{-1, 0} {
-			if got := clip("世界", limit); got != "" {
-				t.Fatalf("clipper limit %d = %q, want empty", limit, got)
-			}
-		}
-	}
-}
-
-func TestProjectCompactionInputDropsRecoverableToolBodies(t *testing.T) {
-	largeBody := strings.Repeat("recoverable source line\n", 1000)
-	messages := []zeroruntime.Message{
-		{Role: zeroruntime.MessageRoleUser, Content: "Inspect the parser and preserve its current behavior."},
-		{Role: zeroruntime.MessageRoleAssistant, Content: "I will inspect before editing.", ToolCalls: []zeroruntime.ToolCall{{ID: "read", Name: "read_file", Arguments: `{"path":"internal/parser.go"}`}}},
-		{Role: zeroruntime.MessageRoleTool, ToolCallID: "read", Content: largeBody},
-		{Role: zeroruntime.MessageRoleAssistant, ToolCalls: []zeroruntime.ToolCall{{ID: "test", Name: "exec_command", Arguments: `{"cmd":"go test ./internal/parser"}`}}},
-		{Role: zeroruntime.MessageRoleTool, ToolCallID: "test", Content: "Error: parser regression\nlong diagnostic details"},
-	}
-
-	projection := projectCompactionInput(messages)
-	projected := projection.messages
-	if len(projected) != 1 {
-		t.Fatalf("projection = %#v, want one compact message", projected)
-	}
-	content := projected[0].Content
-	for _, want := range []string{"Inspect the parser", `read_file "internal/parser.go"`, `exec_command "go test ./internal/parser"`, "Error: parser regression"} {
-		if !strings.Contains(content, want) {
-			t.Fatalf("projection missing %q: %q", want, content)
-		}
-	}
-	if strings.Contains(content, "recoverable source line") || strings.Contains(content, "long diagnostic details") {
-		t.Fatalf("projection retained reconstructible or overlong tool output: %q", content)
-	}
-	if estimateTokens(projected)*20 >= estimateTokens(messages) {
-		t.Fatalf("projection did not materially reduce tokens: before=%d after=%d", estimateTokens(messages), estimateTokens(projected))
-	}
-}
-
-func TestProjectCompactionInputRetainsStructurallyMarkedToolErrors(t *testing.T) {
-	messages := []zeroruntime.Message{
-		{Role: zeroruntime.MessageRoleAssistant, ToolCalls: []zeroruntime.ToolCall{{ID: "git", Name: "exec_command", Arguments: `{"cmd":"git status"}`}}},
-		{Role: zeroruntime.MessageRoleTool, ToolCallID: "git", Content: "fatal: not a git repository", IsError: true},
-	}
-
-	projected := projectCompactionInput(messages).messages
-	if len(projected) != 1 || !strings.Contains(projected[0].Content, "fatal: not a git repository") {
-		t.Fatalf("structured tool error was dropped from projection: %#v", projected)
-	}
-}
-
-func TestProjectCompactionInputRetainsAskUserExchangeAndSemanticArguments(t *testing.T) {
-	messages := []zeroruntime.Message{
-		{Role: zeroruntime.MessageRoleAssistant, ToolCalls: []zeroruntime.ToolCall{{ID: "ask", Name: "ask_user", Arguments: `{"questions":[{"question":"Which database should remain?"}]}`}}},
-		{Role: zeroruntime.MessageRoleTool, ToolCallID: "ask", Content: "Which database should remain?: Postgres only; do not touch MySQL."},
-		{Role: zeroruntime.MessageRoleAssistant, ToolCalls: []zeroruntime.ToolCall{
-			{ID: "patch", Name: "apply_patch", Arguments: `{"patch":"*** Begin Patch\n*** Update File: internal/db.go\n*** End Patch"}`},
-			{ID: "fetch", Name: "web_fetch", Arguments: `{"url":"https://example.com/spec"}`},
-			{ID: "task", Name: "task", Arguments: `{"prompt":"Inspect the Windows implementation"}`},
-		}},
-		{Role: zeroruntime.MessageRoleTool, ToolCallID: "patch", Content: "Done!", ChangedFiles: []string{"internal/db.go"}},
-	}
-
-	content := projectCompactionInput(messages).messages[0].Content
-	for _, want := range []string{"Which database should remain?", "Postgres only; do not touch MySQL", "internal/db.go", "https://example.com/spec", "Inspect the Windows implementation"} {
-		if !strings.Contains(content, want) {
-			t.Fatalf("projection missing %q: %q", want, content)
-		}
-	}
-}
-
-func TestProjectCompactionInputCapsToolCallsPerTurn(t *testing.T) {
-	calls := make([]zeroruntime.ToolCall, 12)
-	for index := range calls {
-		calls[index] = zeroruntime.ToolCall{Name: "read_file", Arguments: `{"path":"file.go"}`}
-	}
-	projected := projectCompactionInput([]zeroruntime.Message{{Role: zeroruntime.MessageRoleAssistant, ToolCalls: calls}}).messages
-	content := projected[0].Content
-	if strings.Count(content, "* read_file") != compactionToolCallsPerTurn || !strings.Contains(content, "4 earlier tool calls omitted") {
-		t.Fatalf("tool-call tail was not bounded: %q", content)
-	}
-}
-
-func TestProjectCompactionInputCarriesPreviousSummaryOutsideBriefCap(t *testing.T) {
-	previous := "keep the earlier architecture decision\n" + strings.Repeat("prior detail ", 2000) + "\nkeep the newest prior decision"
-	messages := []zeroruntime.Message{{Role: zeroruntime.MessageRoleUser, Content: summaryLabel + "\n" + previous + "\n\n" + preservedStateLabel + "\n{}"}}
-	for index := range 500 {
-		messages = append(messages, zeroruntime.Message{Role: zeroruntime.MessageRoleAssistant, Content: strings.Repeat("later transcript detail ", 20)})
-		messages = append(messages, zeroruntime.Message{Role: zeroruntime.MessageRoleUser, Content: "later request " + strings.Repeat("context ", 20) + string(rune('a'+index%26))})
-	}
-
-	projection := projectCompactionInput(messages)
-	content := projection.messages[0].Content
-	if !strings.Contains(content, "[previous summary]\nkeep the earlier architecture decision") || !strings.Contains(content, "keep the newest prior decision") {
-		t.Fatalf("previous summary was lost when the brief tail was capped: %q", content)
-	}
-	if !strings.Contains(content, "middle transcript omitted to fit compaction budget") {
-		t.Fatalf("oversized brief was not head/tail capped: %q", content)
-	}
-	if !projection.truncated {
-		t.Fatal("projection did not structurally report truncation")
-	}
-}
-
-func TestProjectCompactionInputDoesNotInferTruncationFromUserText(t *testing.T) {
-	projection := projectCompactionInput([]zeroruntime.Message{{
-		Role: zeroruntime.MessageRoleUser, Content: "Keep this literal marker: [middle omitted]",
-	}})
-	if projection.truncated {
-		t.Fatal("literal user text produced a false truncation signal")
-	}
-}

internal/agent/compaction_recent_edits_test.go

@@ -20,15 +20,11 @@ func TestRecentEditsExtractsPathsAndNotes(t *testing.T) {
 			{ID: "e2", Name: "edit_file", Arguments: `{"path":"internal/bar.go","old_string":"a","new_string":"b"}`},
 		}},
 		{Role: zeroruntime.MessageRoleTool, ToolCallID: "e2", Content: "Applied edit to internal/bar.go"},
-		{Role: zeroruntime.MessageRoleAssistant, ToolCalls: []zeroruntime.ToolCall{
-			{ID: "e3", Name: "apply_patch", Arguments: `{"patch":"*** Update File: internal/baz.go"}`},
-		}},
-		{Role: zeroruntime.MessageRoleTool, ToolCallID: "e3", Content: "Done!", ChangedFiles: []string{"internal/baz.go"}},
 	}
 
 	edits := recentEdits(messages)
-	if len(edits) != 3 {
-		t.Fatalf("expected 3 edited files, got %d: %#v", len(edits), edits)
+	if len(edits) != 2 {
+		t.Fatalf("expected 2 edited files, got %d: %#v", len(edits), edits)
 	}
 	if edits[0].name != "internal/foo.go" || !strings.Contains(edits[0].body, "12 lines") {
 		t.Fatalf("first edit = %#v, want foo.go with its note", edits[0])
@@ -36,9 +32,6 @@ func TestRecentEditsExtractsPathsAndNotes(t *testing.T) {
 	if edits[1].name != "internal/bar.go" || !strings.Contains(edits[1].body, "Applied edit") {
 		t.Fatalf("second edit = %#v, want bar.go with its note", edits[1])
 	}
-	if edits[2].name != "internal/baz.go" || edits[2].body != "Done!" {
-		t.Fatalf("third edit = %#v, want apply_patch changed file with its note", edits[2])
-	}
 }
 
 // After compaction elides the editing turns, the preserved-state block still

internal/agent/compaction_test.go

@@ -58,15 +58,12 @@ func TestCompactKeepsSystemAndPreservedSuffix(t *testing.T) {
 	if last.Content != "most recent question" {
 		t.Fatalf("expected most recent message preserved, got %q", last.Content)
 	}
-	// The summarizer receives a compact semantic projection of the middle rather
-	// than reconstructible raw tool output.
-	if len(captured) != 1 || captured[0].Role != zeroruntime.MessageRoleUser {
-		t.Fatalf("expected one projected summary input, got %#v", captured)
+	// The summarized middle excludes system and preserved suffix.
+	if len(captured) != 3 {
+		t.Fatalf("expected 3 summarized messages, got %d: %#v", len(captured), captured)
 	}
-	for _, want := range []string{"[user #0]", "first question", "[assistant #1]", "first answer", "second question"} {
-		if !strings.Contains(captured[0].Content, want) {
-			t.Fatalf("projected summary input missing %q: %q", want, captured[0].Content)
-		}
+	if captured[0].Content != "first question" {
+		t.Fatalf("expected oldest non-system message first, got %#v", captured[0])
 	}
 	// Compaction must shrink the conversation.
 	if estimateTokens(result) >= estimateTokens(messages) {

internal/agent/loop.go

@@ -187,13 +187,6 @@ func Run(ctx context.Context, prompt string, provider Provider, options Options)
 
 	guards := newGuardState()
 	task := newTaskState(prompt, options.Trace)
-	onPermission := options.OnPermission
-	options.OnPermission = func(event PermissionEvent) {
-		task.observe(taskStateEvent{kind: taskStateEventPermission, permission: event})
-		if onPermission != nil {
-			onPermission(event)
-		}
-	}
 	compactor := newCompactionState(options, task)
 	defer func() {
 		// A final transcript comparison is observational. It records drift but
@@ -705,7 +698,7 @@ func Run(ctx context.Context, prompt string, provider Provider, options Options)
 			}
 			options.Trace.Counter(trace.CounterToolCalls, 1)
 			recordOutputBudgetTrace(options.Trace, toolResult)
-			task.observe(taskStateEvent{kind: taskStateEventToolResult, arguments: call.Arguments, toolResult: toolResult})
+			task.observe(taskStateEvent{kind: taskStateEventToolResult, toolResult: toolResult})
 			if options.OnToolResult != nil {
 				options.OnToolResult(toolResult)
 			}
@@ -719,11 +712,9 @@ func Run(ctx context.Context, prompt string, provider Provider, options Options)
 				turnRequestedModel = toolResult.RequestedModel
 			}
 			messages = append(messages, zeroruntime.Message{
-				Role:         zeroruntime.MessageRoleTool,
-				Content:      toolResult.Output,
-				ToolCallID:   toolResult.ToolCallID,
-				IsError:      toolResult.Status == tools.StatusError,
-				ChangedFiles: append([]string(nil), toolResult.ChangedFiles...),
+				Role:       zeroruntime.MessageRoleTool,
+				Content:    toolResult.Output,
+				ToolCallID: toolResult.ToolCallID,
 			})
 			// Images ride a following USER message rather than the tool result
 			// above. Every provider drops images on a tool-role message —
@@ -3287,7 +3278,6 @@ func appendAbortedToolResults(messages []Message, remaining []ToolCall) []Messag
 			Role:       zeroruntime.MessageRoleTool,
 			Content:    abortedToolResultNotice,
 			ToolCallID: call.ID,
-			IsError:    true,
 		})
 	}
 	return messages
@@ -3318,9 +3308,6 @@ func copyMessages(messages []Message) []Message {
 		if message.Reasoning != nil {
 			copied[index].Reasoning = append([]zeroruntime.ReasoningBlock{}, message.Reasoning...)
 		}
-		if message.ChangedFiles != nil {
-			copied[index].ChangedFiles = append([]string(nil), message.ChangedFiles...)
-		}
 		// Deep-copy image attachments (slice AND each Data byte slice) so the
 		// raw image bytes are never aliased across history/request/result copies.
 		copied[index].Images = zeroruntime.CloneImageBlocks(message.Images)

internal/agent/loop_test.go

@@ -3592,11 +3592,6 @@ func TestRunAppendsAbortedPlaceholderForUnexecutedToolCallsOnGuardStop(t *testin
 	if !strings.Contains(strings.ToLower(placeholder), "aborted") {
 		t.Fatalf("expected the placeholder result to mark the call as aborted, got %q", placeholder)
 	}
-	for _, message := range result.Messages {
-		if message.ToolCallID == "flaky-2" && !message.IsError {
-			t.Fatalf("aborted placeholder must carry error status: %#v", message)
-		}
-	}
 
 	// Every tool_use in the final assistant message must have a matching result.
 	for _, message := range result.Messages {
@@ -3611,33 +3606,6 @@ func TestRunAppendsAbortedPlaceholderForUnexecutedToolCallsOnGuardStop(t *testin
 	}
 }
 
-func TestRunCarriesToolErrorStatusIntoMessageHistory(t *testing.T) {
-	registry := tools.NewRegistry()
-	registry.Register(alwaysFailingTool{})
-	provider := &mockProvider{turns: [][]zeroruntime.StreamEvent{
-		{
-			{Type: zeroruntime.StreamEventToolCallStart, ToolCallID: "failed-call", ToolName: "flaky"},
-			{Type: zeroruntime.StreamEventToolCallEnd, ToolCallID: "failed-call"},
-			{Type: zeroruntime.StreamEventDone},
-		},
-		{{Type: zeroruntime.StreamEventText, Content: "done"}, {Type: zeroruntime.StreamEventDone}},
-	}}
-
-	result, err := Run(context.Background(), "go", provider, Options{Registry: registry})
-	if err != nil {
-		t.Fatal(err)
-	}
-	for _, message := range result.Messages {
-		if message.ToolCallID == "failed-call" {
-			if !message.IsError {
-				t.Fatalf("failed tool result lost its structured status: %#v", message)
-			}
-			return
-		}
-	}
-	t.Fatalf("failed tool result missing from message history: %#v", result.Messages)
-}
-
 type secretEmittingTool struct{ output string }
 
 func (t secretEmittingTool) Name() string        { return "leak" }

internal/agent/system_prompt.md

@@ -30,11 +30,13 @@ work.
    read-before-edit discipline: inspect the target file and nearby callers,
    tests, or config before you modify behavior. Never edit a file you have not
    read.
-2. **Plan.** For multi-step work, call update_plan with an ordered checklist and
-   keep it current at meaningful milestones. Mark completed work and the next
-   in-progress step together when practical; do not spend separate model turns
-   updating the plan after every file or command. Keep at most one item
-   in_progress. Skip the plan for trivial one-step tasks.
+2. **Plan.** Use update_plan for implementation or investigation that has at
+   least three meaningful dependent steps, then keep it current at milestones.
+   Mark completed work and the next in-progress step together when practical;
+   do not spend separate turns updating it after every file or command. Keep at
+   most one item in_progress. Skip plans for simple lookups, explanations, code
+   navigation, and other short tasks. Never create a plan after the work is
+   already complete merely to describe what you did.
 3. **Implement.** Make focused changes that match the surrounding code's style,
    naming, and conventions. Prefer the smallest change that fully solves the
    problem. Avoid broad refactors, unrelated rewrites, dependency churn, and
@@ -49,9 +51,13 @@ work.
 ## Editing discipline
 
 - Choose the narrowest tool that safely accomplishes the step. Prefer native
-  file tools - read_file, list_directory, glob, grep, write_file, edit_file,
-  apply_patch - over shelling out to cat/sed/awk/python for file operations.
+  file tools - read_file, read_minified_file, list_directory, glob, grep,
+  write_file, edit_file, apply_patch - over shelling out to
+  cat/sed/awk/python for file operations.
   They are safer, reviewable, and produce clean diffs.
+- Prefer read_minified_file when initially exploring source code; it preserves
+  code while removing comments and redundant whitespace. Use read_file when
+  exact text, comments, or line numbers are needed.
 - Keep edits focused and reviewable. A single patch may update several related
   files when they form one coherent change; do not hide unrelated edits in a
   bulk shell or script rewrite.

internal/agent/system_prompt_models.go

@@ -71,5 +71,6 @@ const geminiPromptAddendum = `<model_guidance>
   equivalent shell commands; they are safer and produce cleaner diffs.
 - Be concise and concrete. When you run a shell command with side effects, state
   in one short clause why it is needed.
-- Use update_plan for any multi-step task and keep it current.
+- Use update_plan only for work with at least three meaningful dependent steps;
+  skip it for simple lookups and never create one after the work is complete.
 </model_guidance>`

internal/agent/task_state.go

@@ -1,14 +1,10 @@
 package agent
 
 import (
-	"crypto/sha256"
 	"encoding/json"
-	"fmt"
 	"reflect"
-	"regexp"
 	"sort"
 	"strings"
-	"unicode/utf8"
 
 	"github.com/Gitlawb/zero/internal/tools"
 	"github.com/Gitlawb/zero/internal/trace"
@@ -56,41 +52,17 @@ type taskVerificationState struct {
 	LastOutcome Outcome `json:"last_outcome,omitempty"`
 }
 
-type taskFailureState struct {
-	Key     string `json:"key,omitempty"`
-	Tool    string `json:"tool"`
-	Command string `json:"command,omitempty"`
-	Summary string `json:"summary"`
-}
-
-type taskApprovalState struct {
-	Tool     string                   `json:"tool"`
-	Decision PermissionDecisionAction `json:"decision,omitempty"`
-	Scope    string                   `json:"scope,omitempty"`
-	Reason   string                   `json:"reason,omitempty"`
-}
-
-type taskArtifactState struct {
-	Tool string `json:"tool"`
-	Path string `json:"path"`
-}
-
 type taskStateSnapshot struct {
-	Revision            int                   `json:"revision"`
-	Objective           string                `json:"objective"`
-	Status              taskStatus            `json:"status"`
-	Plan                taskPlanState         `json:"plan"`
-	Tools               taskToolState         `json:"tools"`
-	Verification        taskVerificationState `json:"verification"`
-	ChangedFiles        []string              `json:"changed_files,omitempty"`
-	Constraints         []string              `json:"constraints,omitempty"`
-	UnresolvedFailures  []taskFailureState    `json:"unresolved_failures,omitempty"`
-	Approvals           []taskApprovalState   `json:"approvals,omitempty"`
-	Artifacts           []taskArtifactState   `json:"artifacts,omitempty"`
-	ResolvedFailureKeys []string              `json:"-"`
-	CompletionDecision  CompletionDecision    `json:"completion_decision,omitempty"`
-	CompletionReason    string                `json:"completion_reason,omitempty"`
-	PlanParity          taskPlanParity        `json:"plan_parity"`
+	Revision           int                   `json:"revision"`
+	Objective          string                `json:"objective"`
+	Status             taskStatus            `json:"status"`
+	Plan               taskPlanState         `json:"plan"`
+	Tools              taskToolState         `json:"tools"`
+	Verification       taskVerificationState `json:"verification"`
+	ChangedFiles       []string              `json:"changed_files,omitempty"`
+	CompletionDecision CompletionDecision    `json:"completion_decision,omitempty"`
+	CompletionReason   string                `json:"completion_reason,omitempty"`
+	PlanParity         taskPlanParity        `json:"plan_parity"`
 }
 
 type taskStateEventKind int
@@ -100,7 +72,6 @@ const (
 	taskStateEventToolResult
 	taskStateEventVerification
 	taskStateEventCompletion
-	taskStateEventPermission
 )
 
 type taskStateEvent struct {
@@ -109,7 +80,6 @@ type taskStateEvent struct {
 	toolResult   ToolResult
 	verification Outcome
 	completion   completionEvaluation
-	permission   PermissionEvent
 }
 
 // taskState is a deterministic projection of facts the loop already observes.
@@ -131,7 +101,6 @@ func newTaskState(objective string, recorder *trace.Recorder) *taskState {
 		},
 		changedFiles: map[string]struct{}{},
 	}
-	state.snapshotValue.Constraints = extractExplicitConstraints(objective)
 	state.recorder = recorder
 	return state
 }
@@ -165,7 +134,6 @@ func (state *taskState) observe(event taskStateEvent) bool {
 			}
 		}
 		state.snapshotValue.ChangedFiles = sortedKeys(state.changedFiles)
-		state.observeToolEvidence(event.arguments, event.toolResult)
 		changed = true
 	case taskStateEventVerification:
 		if event.verification == OutcomeDisabled {
@@ -192,10 +160,6 @@ func (state *taskState) observe(event taskStateEvent) bool {
 			state.snapshotValue.Status = taskStatusActive
 		}
 		changed = true
-	case taskStateEventPermission:
-		state.markActive()
-		state.observePermission(event.permission)
-		changed = true
 	}
 	if changed {
 		state.snapshotValue.Revision++
@@ -219,180 +183,9 @@ func (state *taskState) snapshot() taskStateSnapshot {
 	snapshot := state.snapshotValue
 	snapshot.Plan.Items = append([]taskPlanItem(nil), state.snapshotValue.Plan.Items...)
 	snapshot.ChangedFiles = append([]string(nil), state.snapshotValue.ChangedFiles...)
-	snapshot.Constraints = append([]string(nil), state.snapshotValue.Constraints...)
-	snapshot.UnresolvedFailures = append([]taskFailureState(nil), state.snapshotValue.UnresolvedFailures...)
-	snapshot.Approvals = append([]taskApprovalState(nil), state.snapshotValue.Approvals...)
-	snapshot.Artifacts = append([]taskArtifactState(nil), state.snapshotValue.Artifacts...)
-	snapshot.ResolvedFailureKeys = append([]string(nil), state.snapshotValue.ResolvedFailureKeys...)
 	return snapshot
 }
 
-const (
-	maxTaskEvidenceEntries = 8
-	maxTaskEvidenceBytes   = 320
-	maxTaskConstraints     = 10
-)
-
-func (state *taskState) observeToolEvidence(arguments string, result ToolResult) {
-	command := capTaskEvidence(commandFromArguments(arguments))
-	key := taskFailureKey(result.Name, command, arguments)
-	if result.Status == tools.StatusOK {
-		if hasTaskFailure(state.snapshotValue.UnresolvedFailures, key) {
-			state.snapshotValue.UnresolvedFailures = removeTaskFailure(state.snapshotValue.UnresolvedFailures, key)
-			state.snapshotValue.ResolvedFailureKeys = appendBoundedUnique(state.snapshotValue.ResolvedFailureKeys, key, maxTaskEvidenceEntries)
-		}
-	} else {
-		state.snapshotValue.ResolvedFailureKeys = removeString(state.snapshotValue.ResolvedFailureKeys, key)
-		state.snapshotValue.UnresolvedFailures = removeTaskFailure(state.snapshotValue.UnresolvedFailures, key)
-		state.snapshotValue.UnresolvedFailures = appendBounded(state.snapshotValue.UnresolvedFailures, taskFailureState{
-			Key: key, Tool: result.Name, Command: command, Summary: capTaskEvidence(firstLine(result.Output)),
-		}, maxTaskEvidenceEntries)
-	}
-	for _, metaKey := range []string{"spill_path", "artifact_path"} {
-		if path := strings.TrimSpace(result.Meta[metaKey]); path != "" {
-			state.snapshotValue.Artifacts = appendBoundedUnique(state.snapshotValue.Artifacts,
-				taskArtifactState{Tool: result.Name, Path: capTaskEvidence(path)}, maxTaskEvidenceEntries)
-		}
-	}
-}
-
-func taskFailureKey(toolName, command, arguments string) string {
-	identity := command
-	if identity == "" {
-		canonical := []byte(strings.TrimSpace(arguments))
-		var value any
-		if json.Unmarshal(canonical, &value) == nil {
-			if encoded, err := json.Marshal(value); err == nil {
-				canonical = encoded
-			}
-		}
-		digest := sha256.Sum256(canonical)
-		identity = fmt.Sprintf("args:%x", digest[:8])
-	}
-	return strings.TrimSpace(toolName) + "\x00" + identity
-}
-
-func (state *taskState) observePermission(event PermissionEvent) {
-	decision := event.DecisionAction
-	if decision == "" {
-		decision = PermissionDecisionAction(event.Action)
-	}
-	state.snapshotValue.Approvals = appendBoundedUnique(state.snapshotValue.Approvals, taskApprovalState{
-		Tool: event.ToolName, Decision: decision, Scope: capTaskEvidence(event.Scope),
-		Reason: capTaskEvidence(firstNonEmptyString(event.DecisionReason, event.Reason)),
-	}, maxTaskEvidenceEntries)
-}
-
-func commandFromArguments(arguments string) string {
-	var object map[string]json.RawMessage
-	if json.Unmarshal([]byte(strings.TrimSpace(arguments)), &object) != nil {
-		return ""
-	}
-	for _, key := range []string{"cmd", "command", "script", "shell"} {
-		var command string
-		if raw, ok := object[key]; ok && json.Unmarshal(raw, &command) == nil {
-			return strings.TrimSpace(command)
-		}
-	}
-	return ""
-}
-
-func firstLine(value string) string {
-	value = strings.TrimSpace(value)
-	if index := strings.IndexByte(value, '\n'); index >= 0 {
-		value = value[:index]
-	}
-	return value
-}
-
-func capTaskEvidence(value string) string {
-	value = strings.TrimSpace(value)
-	if len(value) <= maxTaskEvidenceBytes {
-		return value
-	}
-	limit := maxTaskEvidenceBytes - 3
-	for limit > 0 && !utf8.RuneStart(value[limit]) {
-		limit--
-	}
-	return strings.TrimSpace(value[:limit]) + "..."
-}
-
-var explicitConstraintPatterns = []*regexp.Regexp{
-	regexp.MustCompile(`(?i)\bprefer(?:s|red|ring)?\s+\w`),
-	regexp.MustCompile(`(?i)\bdon'?t want\b`),
-	regexp.MustCompile(`(?i)\balways (?:use|do|run|prefer|keep|make|format|write|add|set|put|prefix|start|include|append)\b`),
-	regexp.MustCompile(`(?i)\bnever (?:use|do|run|push|commit|write|ignore|add|set|put|remove|delete|include|deploy)\b`),
-	regexp.MustCompile(`(?i)\bplease (?:use|avoid|keep|make|don'?t|do not|format|write)\b`),
-	regexp.MustCompile(`(?i)\b(?:style|format|language|naming)\s*[:=]\s*\S`),
-}
-
-func extractExplicitConstraints(text string) []string {
-	var constraints []string
-	for _, line := range strings.Split(text, "\n") {
-		line = strings.TrimSpace(line)
-		if len(line) < 5 || len(line) > 200 || strings.HasSuffix(line, "?") || strings.Contains(line, "?...") {
-			continue
-		}
-		for _, pattern := range explicitConstraintPatterns {
-			if pattern.MatchString(line) {
-				constraints = appendBoundedUnique(constraints, line, maxTaskConstraints)
-				break
-			}
-		}
-		if len(constraints) == maxTaskConstraints {
-			break
-		}
-	}
-	return constraints
-}
-
-func appendBounded[T any](values []T, value T, limit int) []T {
-	values = append(values, value)
-	if len(values) > limit {
-		values = values[len(values)-limit:]
-	}
-	return values
-}
-
-func appendBoundedUnique[T comparable](values []T, value T, limit int) []T {
-	filtered := values[:0]
-	for _, existing := range values {
-		if existing != value {
-			filtered = append(filtered, existing)
-		}
-	}
-	return appendBounded(filtered, value, limit)
-}
-
-func hasTaskFailure(values []taskFailureState, key string) bool {
-	for _, value := range values {
-		if value.Key == key {
-			return true
-		}
-	}
-	return false
-}
-
-func removeTaskFailure(values []taskFailureState, key string) []taskFailureState {
-	out := values[:0]
-	for _, value := range values {
-		if value.Key != key {
-			out = append(out, value)
-		}
-	}
-	return out
-}
-
-func removeString(values []string, target string) []string {
-	out := make([]string, 0, len(values))
-	for _, value := range values {
-		if value != target {
-			out = append(out, value)
-		}
-	}
-	return out
-}
-
 // observePlanParity compares only the latest plan projection with the plan tool
 // calls still present in messages. It mutates the snapshot and emits when the
 // parity value changes; objective, tool, and verification fields are not part of

internal/agent/task_state_test.go

@@ -115,68 +115,6 @@ func TestTaskStateSnapshotIsImmutable(t *testing.T) {
 	}
 }
 
-func TestTaskStateRecordsDurableRuntimeEvidence(t *testing.T) {
-	state := newTaskState("Please keep the change focused.\nNever commit generated reports.", nil)
-	arguments := `{"cmd":"go test ./internal/agent"}`
-	state.observe(taskStateEvent{kind: taskStateEventToolResult, arguments: arguments, toolResult: ToolResult{
-		ToolCallID: "test-1", Name: "exec_command", Status: tools.StatusError,
-		Output: "Error: TestResumeRetainsState failed\nfull diagnostic",
-		Meta:   map[string]string{"spill_path": ".zero/artifacts/test-1.txt"},
-	}})
-	state.observe(taskStateEvent{kind: taskStateEventPermission, permission: PermissionEvent{
-		ToolName: "exec_command", DecisionAction: PermissionDecisionAllowForSession,
-		Scope: "/tmp", DecisionReason: "write a temporary fixture",
-	}})
-
-	snapshot := state.snapshot()
-	if !reflect.DeepEqual(snapshot.Constraints, []string{"Please keep the change focused.", "Never commit generated reports."}) {
-		t.Fatalf("unexpected explicit constraints: %#v", snapshot.Constraints)
-	}
-	if len(snapshot.UnresolvedFailures) != 1 || snapshot.UnresolvedFailures[0].Command != "go test ./internal/agent" || snapshot.UnresolvedFailures[0].Summary != "Error: TestResumeRetainsState failed" {
-		t.Fatalf("unexpected failure evidence: %#v", snapshot.UnresolvedFailures)
-	}
-	if len(snapshot.Artifacts) != 1 || snapshot.Artifacts[0].Path != ".zero/artifacts/test-1.txt" {
-		t.Fatalf("unexpected artifact evidence: %#v", snapshot.Artifacts)
-	}
-	if len(snapshot.Approvals) != 1 || snapshot.Approvals[0].Decision != PermissionDecisionAllowForSession || snapshot.Approvals[0].Scope != "/tmp" {
-		t.Fatalf("unexpected approval evidence: %#v", snapshot.Approvals)
-	}
-	state.observe(taskStateEvent{kind: taskStateEventToolResult, arguments: `{"path":"a.go"}`, toolResult: ToolResult{
-		ToolCallID: "read-a", Name: "read_file", Status: tools.StatusError, Output: "Error: a.go is unavailable",
-	}})
-	state.observe(taskStateEvent{kind: taskStateEventToolResult, arguments: `{"path":"b.go"}`, toolResult: ToolResult{
-		ToolCallID: "read-b", Name: "read_file", Status: tools.StatusOK, Output: "package b",
-	}})
-	if failures := state.snapshot().UnresolvedFailures; len(failures) != 2 || failures[1].Summary != "Error: a.go is unavailable" {
-		t.Fatalf("success for a different target resolved the wrong failure: %#v", failures)
-	}
-
-	state.observe(taskStateEvent{kind: taskStateEventToolResult, arguments: arguments, toolResult: ToolResult{
-		ToolCallID: "test-2", Name: "exec_command", Status: tools.StatusOK, Output: "ok",
-	}})
-	if failures := state.snapshot().UnresolvedFailures; len(failures) != 1 || failures[0].Summary != "Error: a.go is unavailable" {
-		t.Fatalf("successful retry did not resolve only its matching failure: %#v", failures)
-	}
-	state.observe(taskStateEvent{kind: taskStateEventToolResult, arguments: `{"path":"a.go"}`, toolResult: ToolResult{
-		ToolCallID: "read-a-2", Name: "read_file", Status: tools.StatusOK, Output: "package a",
-	}})
-	if failures := state.snapshot().UnresolvedFailures; len(failures) != 0 {
-		t.Fatalf("successful non-command retry did not resolve its matching failure: %#v", failures)
-	}
-	state.observe(taskStateEvent{kind: taskStateEventToolResult, arguments: `{"path":"a.go"}`, toolResult: ToolResult{
-		ToolCallID: "read-a-3", Name: "read_file", Status: tools.StatusError, Output: "Error: a.go failed again",
-	}})
-	snapshot = state.snapshot()
-	if len(snapshot.UnresolvedFailures) != 1 || snapshot.UnresolvedFailures[0].Summary != "Error: a.go failed again" {
-		t.Fatalf("a failure recurring after success was hidden: %#v", snapshot.UnresolvedFailures)
-	}
-	for _, key := range snapshot.ResolvedFailureKeys {
-		if key == snapshot.UnresolvedFailures[0].Key {
-			t.Fatalf("recurring failure retained a stale resolved key: %#v", snapshot.ResolvedFailureKeys)
-		}
-	}
-}
-
 func TestTaskStatePlanParityUsesLatestPlan(t *testing.T) {
 	state := newTaskState("objective", nil)
 	state.observe(taskStateEvent{kind: taskStateEventPlan, arguments: `{"plan":[{"content":"old","status":"completed"}]}`})

internal/cli/deferred_wiring_test.go

@@ -79,8 +79,8 @@ func TestRegisterToolSearchIfEligibleSkipsWhenThresholdZero(t *testing.T) {
 
 func TestDeferredEligibleCountIncludesOptionalBuiltins(t *testing.T) {
 	registry := newCoreRegistry(t.TempDir())
-	if got := deferredEligibleCount(registry, agent.PermissionModeAuto, nil, nil); got < 3 {
-		t.Fatalf("deferredEligibleCount(core) = %d, want at least 3 optional built-ins", got)
+	if got := deferredEligibleCount(registry, agent.PermissionModeAuto, nil, nil); got < 2 {
+		t.Fatalf("deferredEligibleCount(core) = %d, want at least 2 optional built-ins", got)
 	}
 }
 

internal/minify/minify.go

@@ -13,8 +13,10 @@ package minify
 
 import (
 	"bytes"
+	"go/ast"
 	"go/parser"
 	"go/printer"
+	"go/scanner"
 	"go/token"
 	"path/filepath"
 	"strings"
@@ -34,8 +36,11 @@ func File(path string, content []byte) Result {
 		if out, ok := minifyGo(content); ok {
 			return Result{Content: out, Language: "go", Applied: true}
 		}
-		// Unparsable Go (a snippet, generics edge, or syntax error): fall through
-		// to the safe generic path rather than risk a partial AST reprint.
+		if out, ok := minifyGoFragment(content); ok {
+			return Result{Content: out, Language: "go-fragment", Applied: true}
+		}
+		// An incomplete fragment that cannot be wrapped safely falls through to
+		// whitespace-only normalization; no source text is guessed or discarded.
 	} else if style, ok := commentStyles[ext]; ok {
 		// Strip comments with a string-aware lexer, then collapse the whitespace the
 		// removed comments left behind. The stripper only handles languages whose
@@ -46,6 +51,133 @@ func File(path string, content []byte) Result {
 	return Result{Content: minifyGeneric(content), Language: "text", Applied: false}
 }
 
+// Fragment minifies a bounded source range without assuming lexical state from
+// text outside the range. Go remains parser-validated; other languages use the
+// conservative whitespace-only transform because a range may begin inside a
+// multiline string or block comment.
+func Fragment(path string, content []byte) Result {
+	if strings.EqualFold(filepath.Ext(path), ".go") {
+		if out, ok := minifyGo(content); ok {
+			return Result{Content: out, Language: "go", Applied: true}
+		}
+		if out, ok := minifyGoFragment(content); ok {
+			return Result{Content: out, Language: "go-fragment", Applied: true}
+		}
+	}
+	return Result{Content: minifyGeneric(content), Language: "text", Applied: false}
+}
+
+// ContextualFragment minifies a bounded fragment after checking its starting
+// position against the complete source. A Go range that begins inside a string
+// or comment must remain verbatim apart from whitespace normalization: parsing
+// that fragment by itself would mistake literal text for Go syntax.
+func ContextualFragment(path string, source, content []byte, startOffset int) Result {
+	if strings.EqualFold(filepath.Ext(path), ".go") && goFragmentStartsInsideToken(source, startOffset) {
+		return Result{Content: minifyGeneric(content), Language: "text", Applied: false}
+	}
+	return Fragment(path, content)
+}
+
+func goFragmentStartsInsideToken(source []byte, startOffset int) bool {
+	if startOffset <= 0 || startOffset >= len(source) {
+		return false
+	}
+	fset := token.NewFileSet()
+	file := fset.AddFile("", fset.Base(), len(source))
+	var lexer scanner.Scanner
+	lexer.Init(file, source, nil, scanner.ScanComments)
+	for {
+		position, kind, literal := lexer.Scan()
+		if kind == token.EOF {
+			return false
+		}
+		if kind != token.STRING && kind != token.COMMENT {
+			continue
+		}
+		start := file.Offset(position)
+		if startOffset > start && startOffset < start+len(literal) {
+			return true
+		}
+	}
+}
+
+// minifyGoFragment handles bounded reads that do not contain a package clause.
+// It finds the longest complete declaration or statement prefix that the real
+// Go parser accepts, prints that prefix without comments, and preserves any
+// incomplete tail conservatively. Ranges are intentionally capped: repeatedly
+// parsing a large broken file would otherwise turn a cheap read into O(n²) work.
+func minifyGoFragment(content []byte) (string, bool) {
+	lines := strings.Split(strings.ReplaceAll(string(content), "\r\n", "\n"), "\n")
+	if len(lines) > 1 && lines[len(lines)-1] == "" {
+		lines = lines[:len(lines)-1]
+	}
+	if len(lines) > 512 {
+		return "", false
+	}
+	for end := len(lines); end > 0; end-- {
+		prefix := strings.Join(lines[:end], "\n")
+		if compact, ok := parseGoDeclarations(prefix); ok {
+			return joinCompactPrefix(compact, lines[end:]), true
+		}
+		if compact, ok := parseGoStatements(prefix); ok {
+			return joinCompactPrefix(compact, lines[end:]), true
+		}
+	}
+	return "", false
+}
+
+func parseGoDeclarations(fragment string) (string, bool) {
+	fset := token.NewFileSet()
+	file, err := parser.ParseFile(fset, "", "package compact\n"+fragment, parser.SkipObjectResolution)
+	if err != nil || len(file.Decls) == 0 {
+		return "", false
+	}
+	nodes := make([]ast.Node, len(file.Decls))
+	for i, declaration := range file.Decls {
+		nodes[i] = declaration
+	}
+	return printGoNodes(fset, nodes)
+}
+
+func parseGoStatements(fragment string) (string, bool) {
+	fset := token.NewFileSet()
+	file, err := parser.ParseFile(fset, "", "package compact\nfunc _(){\n"+fragment+"\n}", parser.SkipObjectResolution)
+	if err != nil || len(file.Decls) != 1 {
+		return "", false
+	}
+	function, ok := file.Decls[0].(*ast.FuncDecl)
+	if !ok || function.Body == nil || len(function.Body.List) == 0 {
+		return "", false
+	}
+	nodes := make([]ast.Node, len(function.Body.List))
+	for i, statement := range function.Body.List {
+		nodes[i] = statement
+	}
+	return printGoNodes(fset, nodes)
+}
+
+func printGoNodes(fset *token.FileSet, nodes []ast.Node) (string, bool) {
+	var buf bytes.Buffer
+	cfg := printer.Config{Mode: printer.TabIndent, Tabwidth: 1}
+	for i, node := range nodes {
+		if i > 0 {
+			buf.WriteByte('\n')
+		}
+		if err := cfg.Fprint(&buf, fset, node); err != nil {
+			return "", false
+		}
+	}
+	return strings.TrimSpace(buf.String()), true
+}
+
+func joinCompactPrefix(compact string, remainder []string) string {
+	tail := minifyGeneric([]byte(strings.Join(remainder, "\n")))
+	if tail == "" {
+		return compact
+	}
+	return compact + "\n" + tail
+}
+
 // minifyGo parses Go WITHOUT comments (omitting parser.ParseComments leaves them
 // unattached) and reprints the AST, yielding valid, comment-free, gofmt-shaped
 // source with tab indentation (1 char per level). It returns ok=false on any

internal/minify/minify_test.go

@@ -39,17 +39,58 @@ func Greet(name string) string {
 	}
 }
 
-func TestMinifyGoFallsBackOnUnparsableGo(t *testing.T) {
-	// A snippet (no package clause) cannot parse as a file -> safe generic path.
+func TestMinifyGoStatementFragment(t *testing.T) {
 	r := File("snippet.go", []byte("x := 1   \n\n\n// keep me\ny := 2\n"))
-	if r.Applied {
-		t.Fatalf("expected fallback for unparsable Go, got %+v", r)
+	if !r.Applied || r.Language != "go-fragment" {
+		t.Fatalf("expected parsed Go fragment, got %+v", r)
 	}
 	if strings.Contains(r.Content, "\n\n\n") {
-		t.Errorf("generic should collapse blank runs:\n%q", r.Content)
+		t.Errorf("fragment should collapse blank runs:\n%q", r.Content)
 	}
-	if !strings.Contains(r.Content, "// keep me") {
-		t.Errorf("generic must NOT strip comments (unsafe without a parser): %q", r.Content)
+	if strings.Contains(r.Content, "keep me") || !strings.Contains(r.Content, "y := 2") {
+		t.Errorf("fragment was not compacted safely: %q", r.Content)
+	}
+}
+
+func TestMinifyGoFragmentAccepts512LinesWithFinalNewline(t *testing.T) {
+	src := strings.Repeat("x++\n", 512)
+	r := File("snippet.go", []byte(src))
+	if !r.Applied || r.Language != "go-fragment" {
+		t.Fatalf("expected 512-line fragment to remain eligible, got %+v", r)
+	}
+	if got := strings.Count(r.Content, "x++"); got != 512 {
+		t.Fatalf("compacted statement count = %d, want 512", got)
+	}
+}
+
+func TestMinifyGoDeclarationPrefixPreservesIncompleteTail(t *testing.T) {
+	src := `func Handle737(n int) (int, error) {
+	if n%2 == 1 {
+		return 0, errBad
+	}
+	return n + 737, nil
+}
+
+// Handle738 begins outside the requested range.
+func Handle738(n int) (int, error) {
+	if n%2 == 1 {`
+	r := File("range.go", []byte(src))
+	if !r.Applied || r.Language != "go-fragment" {
+		t.Fatalf("expected declaration-prefix compaction, got %+v", r)
+	}
+	if strings.Contains(r.Content, "Handle737 returns") || !strings.Contains(r.Content, "return n + 737") {
+		t.Fatalf("complete declaration was not compacted correctly:\n%s", r.Content)
+	}
+	if !strings.Contains(r.Content, "func Handle738") || !strings.Contains(r.Content, "if n%2 == 1 {") {
+		t.Fatalf("incomplete tail was not preserved:\n%s", r.Content)
+	}
+}
+
+func TestMinifyGoLargeInvalidInputFallsBackConservatively(t *testing.T) {
+	src := strings.Repeat("x := 1 // keep\n", 513)
+	r := File("broken.go", []byte(src))
+	if r.Applied || !strings.Contains(r.Content, "// keep") {
+		t.Fatalf("large invalid input must retain conservative fallback: %+v", r)
 	}
 }
 

internal/sessions/replay.go

@@ -7,7 +7,6 @@ import (
 	"unicode/utf8"
 
 	"github.com/Gitlawb/zero/internal/redaction"
-	"github.com/Gitlawb/zero/internal/zeroruntime"
 )
 
 type EventRef struct {
@@ -38,7 +37,6 @@ type RewindPlan struct {
 type CompactionOptions struct {
 	PreserveLast   int
 	MaxPromptChars int
-	SkipPrompt     bool
 }
 
 type CompactionPlan struct {
@@ -49,9 +47,8 @@ type CompactionPlan struct {
 	CompactableEvents []EventRef `json:"compactableEvents"`
 	PreservedEvents   []EventRef `json:"preservedEvents"`
 	SummaryPrompt     string     `json:"summaryPrompt"`
-	// PromptChars counts prompt text content and excludes provider protocol framing.
-	PromptChars int  `json:"promptChars"`
-	Truncated   bool `json:"truncated,omitempty"`
+	PromptChars       int        `json:"promptChars"`
+	Truncated         bool       `json:"truncated,omitempty"`
 }
 
 type RecordCompactionInput struct {
@@ -167,11 +164,7 @@ func (store *Store) PlanCompaction(sessionID string, options CompactionOptions)
 	}
 	compactable := events[:split]
 	preserved := events[split:]
-	prompt := ""
-	truncated := false
-	if !options.SkipPrompt {
-		prompt, truncated = buildCompactionPrompt(compactable, maxPromptChars)
-	}
+	prompt, truncated := buildCompactionPrompt(compactable, maxPromptChars)
 	return CompactionPlan{
 		SessionID:         sessionID,
 		PreserveLast:      preserveLast,
@@ -319,88 +312,6 @@ func buildCompactionPrompt(events []Event, maxChars int) (string, bool) {
 	return prompt, false
 }
 
-// CompactionMessages converts durable session events into the same normalized
-// message shape used by the running agent's compaction pipeline. Provider usage
-// and checkpoint blobs are omitted. Message/tool fields rely on the session
-// writer's invariant that tool output is scrubbed before persistence;
-// ask_user answers and generic event previews are redacted here.
-func CompactionMessages(events []Event) []zeroruntime.Message {
-	messages := make([]zeroruntime.Message, 0, len(events))
-	for _, event := range events {
-		var payload map[string]any
-		_ = json.Unmarshal(event.Payload, &payload)
-		stringField := func(key string) string {
-			value, _ := payload[key].(string)
-			return strings.TrimSpace(value)
-		}
-		switch event.Type {
-		case EventMessage:
-			role := strings.ToLower(stringField("role"))
-			content := stringField("content")
-			switch role {
-			case "user":
-				messages = append(messages, zeroruntime.Message{Role: zeroruntime.MessageRoleUser, Content: content})
-			case "assistant":
-				messages = append(messages, zeroruntime.Message{Role: zeroruntime.MessageRoleAssistant, Content: content})
-			case "ask_user_answers":
-				if answers, ok := payload["answers"]; ok {
-					encoded, _ := json.Marshal(answers)
-					messages = append(messages, zeroruntime.Message{Role: zeroruntime.MessageRoleUser, Content: "User answers: " + redaction.RedactString(string(encoded), redaction.Options{})})
-				}
-			default:
-				if content != "" {
-					messages = append(messages, zeroruntime.Message{Role: zeroruntime.MessageRoleUser, Content: content})
-				}
-			}
-		case EventToolCall:
-			messages = append(messages, zeroruntime.Message{Role: zeroruntime.MessageRoleAssistant, ToolCalls: []zeroruntime.ToolCall{{
-				ID: firstSessionString(stringField("toolCallId"), stringField("id")), Name: firstSessionString(stringField("name"), stringField("toolName")), Arguments: stringField("arguments"),
-			}}})
-		case EventToolResult:
-			status := strings.ToLower(stringField("status"))
-			messages = append(messages, zeroruntime.Message{
-				Role: zeroruntime.MessageRoleTool, ToolCallID: firstSessionString(stringField("toolCallId"), stringField("id")),
-				Content: stringField("output"), IsError: status != "" && status != "ok", ChangedFiles: sessionStringSlice(payload["changedFiles"]),
-			})
-		case EventCompaction:
-			if summary := stringField("summary"); summary != "" {
-				messages = append(messages, zeroruntime.Message{Role: zeroruntime.MessageRoleUser, Content: "[Summary of earlier conversation]\n" + summary})
-			}
-		case EventProviderUsage, EventSessionCheckpoint:
-			continue
-		default:
-			preview := shapedPayloadPreview(event)
-			if strings.TrimSpace(preview) != "" && preview != "{}" {
-				messages = append(messages, zeroruntime.Message{Role: zeroruntime.MessageRoleUser, Content: fmt.Sprintf("[%s] %s", event.Type, preview)})
-			}
-		}
-	}
-	return messages
-}
-
-func firstSessionString(values ...string) string {
-	for _, value := range values {
-		if strings.TrimSpace(value) != "" {
-			return strings.TrimSpace(value)
-		}
-	}
-	return ""
-}
-
-func sessionStringSlice(value any) []string {
-	raw, ok := value.([]any)
-	if !ok {
-		return nil
-	}
-	values := make([]string, 0, len(raw))
-	for _, item := range raw {
-		if text, ok := item.(string); ok && strings.TrimSpace(text) != "" {
-			values = append(values, strings.TrimSpace(text))
-		}
-	}
-	return values
-}
-
 func shapedPayloadPreview(event Event) string {
 	switch event.Type {
 	case EventPermission, EventPermissionRequest, EventPermissionDecision:

internal/sessions/replay_test.go

@@ -5,27 +5,8 @@ import (
 	"strings"
 	"testing"
 	"time"
-
-	"github.com/Gitlawb/zero/internal/zeroruntime"
 )
 
-func TestCompactionMessagesPreservesInteractiveAndMutationEvidence(t *testing.T) {
-	events := []Event{
-		{Type: EventToolCall, Payload: json.RawMessage(`{"id":"ask","name":"ask_user","arguments":"{\"questions\":[{\"question\":\"Which database?\"}]}"}`)},
-		{Type: EventToolResult, Payload: json.RawMessage(`{"toolCallId":"ask","name":"ask_user","status":"ok","output":"Postgres only"}`)},
-		{Type: EventToolCall, Payload: json.RawMessage(`{"id":"patch","name":"apply_patch","arguments":"{\"patch\":\"*** Update File: db.go\"}"}`)},
-		{Type: EventToolResult, Payload: json.RawMessage(`{"toolCallId":"patch","name":"apply_patch","status":"ok","output":"Done!","changedFiles":["db.go"]}`)},
-	}
-
-	messages := CompactionMessages(events)
-	if len(messages) != 4 || messages[0].Role != zeroruntime.MessageRoleAssistant || messages[1].Role != zeroruntime.MessageRoleTool {
-		t.Fatalf("unexpected normalized compaction messages: %#v", messages)
-	}
-	if messages[1].Content != "Postgres only" || len(messages[3].ChangedFiles) != 1 || messages[3].ChangedFiles[0] != "db.go" {
-		t.Fatalf("interactive or mutation evidence was lost: %#v", messages)
-	}
-}
-
 func TestStorePlansRewindBySequence(t *testing.T) {
 	store := NewStore(StoreOptions{RootDir: t.TempDir(), Now: sequenceClock([]time.Time{
 		time.Date(2026, 6, 6, 10, 0, 0, 0, time.UTC),
@@ -149,26 +130,6 @@ func TestStorePlansCompactionWindow(t *testing.T) {
 	}
 }
 
-func TestStoreCanPlanCompactionWithoutBuildingLegacyPrompt(t *testing.T) {
-	store := NewStore(StoreOptions{RootDir: t.TempDir()})
-	session, err := store.Create(CreateInput{SessionID: "compactnoprompt"})
-	if err != nil {
-		t.Fatal(err)
-	}
-	for _, content := range []string{"one", "two", "three"} {
-		if _, err := store.AppendEvent(session.SessionID, AppendEventInput{Type: EventMessage, Payload: map[string]string{"content": content}}); err != nil {
-			t.Fatal(err)
-		}
-	}
-	plan, err := store.PlanCompaction(session.SessionID, CompactionOptions{PreserveLast: 1, SkipPrompt: true})
-	if err != nil {
-		t.Fatal(err)
-	}
-	if plan.CompactableCount != 2 || plan.SummaryPrompt != "" || plan.PromptChars != 0 || plan.Truncated {
-		t.Fatalf("unexpected prompt-free plan: %#v", plan)
-	}
-}
-
 func TestStoreCompactionShapesSensitivePermissionEvents(t *testing.T) {
 	secret := "sk-proj-abcdefghijklmnopqrstuvwxyz"
 	store := NewStore(StoreOptions{RootDir: t.TempDir()})

internal/tools/file_safety_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"os"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"testing"
 )
@@ -295,6 +296,40 @@ func TestEditFileAllowsSeenRangeAndRejectsUnseenRange(t *testing.T) {
 	}
 }
 
+func TestCanonicalLimitedReadAuthorizesEdit(t *testing.T) {
+	dir := t.TempDir()
+	var source strings.Builder
+	for line := 1; line <= 1000; line++ {
+		source.WriteString("line ")
+		source.WriteString(strconv.Itoa(line))
+		source.WriteByte('\n')
+	}
+	path := filepath.Join(dir, "f.txt")
+	if err := os.WriteFile(path, []byte(source.String()), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	registry := safetyRegistry(t, dir)
+	tracker := NewFileTracker()
+	opts := grantedOpts(tracker)
+
+	read := registry.RunWithOptions(context.Background(), "read_file", map[string]any{
+		"path": "f.txt", "offset": 500, "limit": 10,
+	}, opts)
+	if read.Status != StatusOK || read.Truncated {
+		t.Fatalf("bounded canonical read must be exact: status=%s truncated=%v meta=%#v", read.Status, read.Truncated, read.Meta)
+	}
+	if read.Meta["seen_lines"] != "500-509" {
+		t.Fatalf("bounded canonical read did not receive exact-read credit: %#v", read.Meta)
+	}
+
+	edit := registry.RunWithOptions(context.Background(), "edit_file", map[string]any{
+		"path": "f.txt", "old_string": "line 505", "new_string": "updated 505",
+	}, opts)
+	if edit.Status != StatusOK {
+		t.Fatalf("edit inside canonical read range was refused: %s", edit.Output)
+	}
+}
+
 func TestEditFileReplaceAllRecordsEveryShiftedReplacementSpan(t *testing.T) {
 	dir := t.TempDir()
 	path := filepath.Join(dir, "f.txt")

internal/tools/file_tools_test.go

@@ -38,6 +38,108 @@ func TestReadFileToolReadsLineRanges(t *testing.T) {
 	}
 }
 
+func TestReadFileToolReadsCanonicalLineRange(t *testing.T) {
+	root := t.TempDir()
+	writeTestFile(t, filepath.Join(root, "notes.txt"), "alpha\nbeta\ngamma\ndelta")
+
+	result := NewScopedReadFileTool(root, nil).Run(context.Background(), map[string]any{
+		"path":   "notes.txt",
+		"offset": 2,
+		"limit":  2,
+	})
+
+	if result.Status != StatusOK {
+		t.Fatalf("expected ok status, got %s: %s", result.Status, result.Output)
+	}
+	if result.Truncated {
+		t.Fatalf("canonical limit defines the requested range and must not mark it truncated: %#v", result.Meta)
+	}
+	if !strings.Contains(result.Output, "2 | beta") || !strings.Contains(result.Output, "3 | gamma") {
+		t.Fatalf("canonical range returned the wrong lines: %q", result.Output)
+	}
+	if strings.Contains(result.Output, "alpha") || strings.Contains(result.Output, "delta") {
+		t.Fatalf("canonical range leaked outside requested slice: %q", result.Output)
+	}
+}
+
+func TestReadFileToolCanonicalOffsetPastEnd(t *testing.T) {
+	root := t.TempDir()
+	writeTestFile(t, filepath.Join(root, "notes.txt"), "alpha\nbeta")
+
+	result := NewScopedReadFileTool(root, nil).Run(context.Background(), map[string]any{
+		"path": "notes.txt", "offset": 10,
+	})
+
+	if result.Status != StatusOK || !strings.Contains(result.Output, "offset 10 is past the end") {
+		t.Fatalf("expected canonical out-of-range message, got status=%s output=%q", result.Status, result.Output)
+	}
+	if strings.Contains(result.Output, "start_line") {
+		t.Fatalf("out-of-range message exposed legacy argument: %q", result.Output)
+	}
+}
+
+func TestReadFileToolMixedLegacyRangesPreferLines(t *testing.T) {
+	root := t.TempDir()
+	writeTestFile(t, filepath.Join(root, "notes.txt"), "alpha\nbeta\ngamma\ndelta")
+
+	result := NewScopedReadFileTool(root, nil).Run(context.Background(), map[string]any{
+		"path":        "notes.txt",
+		"start_line":  2,
+		"end_line":    3,
+		"max_lines":   2,
+		"byte_offset": 0,
+		"byte_limit":  readFileByteChunkMax,
+	})
+
+	if result.Status != StatusOK {
+		t.Fatalf("mixed legacy range should recover, got %s: %s", result.Status, result.Output)
+	}
+	if !strings.Contains(result.Output, "2 | beta") || !strings.Contains(result.Output, "3 | gamma") {
+		t.Fatalf("mixed legacy range did not prefer lines: %q", result.Output)
+	}
+}
+
+func TestReadFileToolCombinesLegacyStartWithCanonicalLimit(t *testing.T) {
+	root := t.TempDir()
+	writeTestFile(t, filepath.Join(root, "notes.txt"), "alpha\nbeta\ngamma\ndelta")
+
+	result := NewScopedReadFileTool(root, nil).Run(context.Background(), map[string]any{
+		"path": "notes.txt", "start_line": 2, "limit": 2,
+	})
+
+	if result.Status != StatusOK || result.Truncated {
+		t.Fatalf("mixed compatible range should be exact, got status=%s truncated=%v: %s", result.Status, result.Truncated, result.Output)
+	}
+	if !strings.Contains(result.Output, "2 | beta") || !strings.Contains(result.Output, "3 | gamma") {
+		t.Fatalf("mixed compatible range returned the wrong lines: %q", result.Output)
+	}
+	if strings.Contains(result.Output, "alpha") || strings.Contains(result.Output, "delta") {
+		t.Fatalf("mixed compatible range leaked outside requested slice: %q", result.Output)
+	}
+}
+
+func TestFileToolSchemasExposeOnlyCanonicalArguments(t *testing.T) {
+	readProperties := NewScopedReadFileTool(t.TempDir(), nil).Parameters().Properties
+	for _, want := range []string{"path", "offset", "limit", "byte_offset", "byte_limit"} {
+		if _, ok := readProperties[want]; !ok {
+			t.Fatalf("read_file schema missing %q", want)
+		}
+	}
+	for _, legacy := range []string{"start_line", "end_line", "max_lines"} {
+		if _, ok := readProperties[legacy]; ok {
+			t.Fatalf("read_file schema must not expose legacy argument %q", legacy)
+		}
+	}
+
+	grepProperties := NewScopedGrepTool(t.TempDir(), nil).Parameters().Properties
+	if _, ok := grepProperties["case_insensitive"]; !ok {
+		t.Fatal("grep schema missing case_insensitive")
+	}
+	if _, ok := grepProperties["-i"]; ok {
+		t.Fatal("grep schema must not expose the -i alias")
+	}
+}
+
 func TestReadFileToolMarksTruncation(t *testing.T) {
 	root := t.TempDir()
 	writeTestFile(t, filepath.Join(root, "notes.txt"), "a\nb\nc\nd\ne")
@@ -52,7 +154,7 @@ func TestReadFileToolMarksTruncation(t *testing.T) {
 	}
 	// The cut must be visible in the rendered output, not just the Truncated flag,
 	// and must tell the model where to continue.
-	if !strings.Contains(result.Output, "[truncated:") || !strings.Contains(result.Output, "start_line=3") {
+	if !strings.Contains(result.Output, "[truncated:") || !strings.Contains(result.Output, "offset=3") {
 		t.Fatalf("expected truncation marker pointing to the next line, got %q", result.Output)
 	}
 }
@@ -68,7 +170,7 @@ func TestReadFileToolAppliesByteBudget(t *testing.T) {
 	if result.Status != StatusOK || !result.Truncated {
 		t.Fatalf("expected ok+truncated, got status=%s truncated=%v", result.Status, result.Truncated)
 	}
-	if !strings.Contains(result.Output, "output exceeded") || !strings.Contains(result.Output, "start_line") {
+	if !strings.Contains(result.Output, "output exceeded") || !strings.Contains(result.Output, "offset/limit") {
 		t.Fatalf("expected byte-budget continuation hint, got %q", result.Output[len(result.Output)-200:])
 	}
 	if result.Meta["raw_bytes"] == "" || result.Meta["emitted_bytes"] == "" {

internal/tools/file_tracker.go

@@ -377,5 +377,5 @@ func fileConflictMessage(relativePath string) string {
 }
 
 func fileUnseenMessage(relativePath string) string {
-	return "Error writing " + relativePath + ": the intended change depends on content that has not been read exactly in this session. Read the affected lines with read_file, or use byte_offset/byte_limit for an oversized single line, then retry the edit."
+	return "Error writing " + relativePath + ": the intended change depends on content that has not been read exactly in this session. Read the affected lines with read_file using offset/limit (or byte_offset/byte_limit for a very long line), then retry the edit."
 }

internal/tools/grep.go

@@ -48,7 +48,6 @@ func NewScopedGrepTool(workspaceRoot string, scope PathScope) Tool {
 					"path":             {Type: "string", Description: "Directory or file to search. Relative paths stay in the workspace; use an absolute path to search a granted extra root. Defaults to workspace root.", Default: "."},
 					"glob":             {Type: "string", Description: `Optional glob filter, for example "**/*.go".`},
 					"output_mode":      {Type: "string", Description: "Output mode.", Enum: []string{"content", "files_with_matches", "count"}, Default: "content"},
-					"-i":               {Type: "boolean", Description: "Case insensitive search.", Default: false},
 					"case_insensitive": {Type: "boolean", Description: "Case insensitive search.", Default: false},
 					"head_limit":       {Type: "integer", Description: "Maximum content results to return.", Default: 50, Minimum: intPtr(1)},
 				},

internal/tools/read_file.go

@@ -31,16 +31,15 @@ func NewScopedReadFileTool(workspaceRoot string, scope PathScope) Tool {
 	return readFileTool{
 		baseTool: baseTool{
 			name:        "read_file",
-			description: "Read a file by 1-based inclusive line range, or by exact byte chunks for oversized single-line files.",
+			description: "Read exact file text with line numbers. Use for comments, formatting, or edits; prefer read_minified_file for initial code understanding. Use offset and limit for a line range.",
 			parameters: Schema{
 				Type: "object",
 				Properties: map[string]PropertySchema{
-					"path":        {Type: "string", Description: "Path of the file to read."},
-					"start_line":  {Type: "integer", Description: "1-based inclusive line number to start reading from.", Minimum: intPtr(1)},
-					"end_line":    {Type: "integer", Description: "1-based inclusive line number to stop reading at.", Minimum: intPtr(1)},
-					"max_lines":   {Type: "integer", Description: "Maximum number of lines to return.", Minimum: intPtr(1)},
-					"byte_offset": {Type: "integer", Description: "Zero-based byte offset for an exact chunk read. Use with byte_limit for oversized single-line files; cannot be combined with line ranges.", Minimum: intPtr(0)},
-					"byte_limit":  {Type: "integer", Description: "Maximum source bytes returned in exact byte mode. Defaults to 65536.", Default: readFileByteChunkMax, Minimum: intPtr(1), Maximum: intPtr(readFileByteChunkMax)},
+					"path":        {Type: "string", Description: "File path."},
+					"offset":      {Type: "integer", Description: "Optional 1-based source line to start from.", Minimum: intPtr(1)},
+					"limit":       {Type: "integer", Description: "Optional number of source lines to return.", Minimum: intPtr(1)},
+					"byte_offset": {Type: "integer", Description: "Optional zero-based offset for exact byte reads.", Minimum: intPtr(0)},
+					"byte_limit":  {Type: "integer", Description: "Optional byte count for an exact byte read; use with byte_offset.", Minimum: intPtr(1), Maximum: intPtr(readFileByteChunkMax)},
 				},
 				Required:             []string{"path"},
 				AdditionalProperties: false,
@@ -69,7 +68,27 @@ func (tool readFileTool) run(args map[string]any, options RunOptions, directBudg
 	if err != nil {
 		return errorResult("Error: Invalid arguments for read_file: " + err.Error())
 	}
-	startLine, err := intArg(args, "start_line", 1, 1, 0)
+	_, hasOffset := args["offset"]
+	_, hasLimit := args["limit"]
+	_, hasStartLine := args["start_line"]
+	_, hasEndLine := args["end_line"]
+	_, hasMaxLines := args["max_lines"]
+	if hasOffset && hasStartLine {
+		return errorResult("Error: Invalid arguments for read_file: use either offset or start_line, not both")
+	}
+	if hasLimit && (hasEndLine || hasMaxLines) {
+		return errorResult("Error: Invalid arguments for read_file: use limit instead of end_line or max_lines, not both")
+	}
+
+	startKey := "offset"
+	if !hasOffset && hasStartLine {
+		startKey = "start_line"
+	}
+	startLine, err := intArg(args, startKey, 1, 1, 0)
+	if err != nil {
+		return errorResult("Error: Invalid arguments for read_file: " + err.Error())
+	}
+	limit, err := intArg(args, "limit", 0, 1, 0)
 	if err != nil {
 		return errorResult("Error: Invalid arguments for read_file: " + err.Error())
 	}
@@ -81,19 +100,25 @@ func (tool readFileTool) run(args map[string]any, options RunOptions, directBudg
 	if err != nil {
 		return errorResult("Error: Invalid arguments for read_file: " + err.Error())
 	}
+	if hasLimit {
+		const maxInt = int(^uint(0) >> 1)
+		endLine = startLine + min(limit-1, maxInt-startLine)
+	}
+	hasLineRange := hasOffset || hasLimit || hasStartLine || hasEndLine || hasMaxLines
 	_, hasByteOffset := args["byte_offset"]
 	_, hasByteLimit := args["byte_limit"]
-	byteMode := hasByteOffset || hasByteLimit
-	byteOffset, err := intArg(args, "byte_offset", 0, 0, 0)
-	if err != nil {
-		return errorResult("Error: Invalid arguments for read_file: " + err.Error())
-	}
-	byteLimit, err := intArg(args, "byte_limit", readFileByteChunkMax, 1, readFileByteChunkMax)
-	if err != nil {
-		return errorResult("Error: Invalid arguments for read_file: " + err.Error())
-	}
-	if byteMode && (args["start_line"] != nil || args["end_line"] != nil || args["max_lines"] != nil) {
-		return errorResult("Error: Invalid arguments for read_file: byte_offset/byte_limit cannot be combined with line ranges")
+	byteMode := (hasByteOffset || hasByteLimit) && !hasLineRange
+	byteOffset := 0
+	byteLimit := readFileByteChunkMax
+	if byteMode {
+		byteOffset, err = intArg(args, "byte_offset", 0, 0, 0)
+		if err != nil {
+			return errorResult("Error: Invalid arguments for read_file: " + err.Error())
+		}
+		byteLimit, err = intArg(args, "byte_limit", readFileByteChunkMax, 1, readFileByteChunkMax)
+		if err != nil {
+			return errorResult("Error: Invalid arguments for read_file: " + err.Error())
+		}
 	}
 
 	absolutePath, relativePath, err := resolveScopedReadPath(tool.workspaceRoot, tool.scope, requestedPath)
@@ -169,7 +194,7 @@ func renderedReadRange(total, start, end, maxLines int) (int, int) {
 
 func renderReadFileRange(absolutePath string, relativePath string, total int, startLine int, endLine int, maxLines int, maxBytes int) Result {
 	if startLine > total {
-		return okResult(fmt.Sprintf("File: %s\n(start_line %d is past the end of the file, which has %d lines)", relativePath, startLine, total))
+		return okResult(fmt.Sprintf("File: %s\n(offset %d is past the end of the file, which has %d lines)", relativePath, startLine, total))
 	}
 	if endLine == 0 || endLine > total {
 		endLine = total
@@ -208,9 +233,9 @@ func renderReadFileRange(absolutePath string, relativePath string, total int, st
 	// Tool.Run calls preserve the legacy prefix-only byte budget.
 	var budgetedOutput *outputBudgetBuilder
 	if maxBytes > 0 {
-		budgetedOutput = newOutputBudgetBuilder(maxBytes, "use start_line/end_line or max_lines for normal files; use byte_offset/byte_limit for an oversized single line")
+		budgetedOutput = newOutputBudgetBuilder(maxBytes, "use offset/limit to request a smaller line range")
 	} else {
-		budgetedOutput = newHeadTailOutputBudgetBuilder(readOutputBudgetBytes, "use start_line/end_line or max_lines for normal files; use byte_offset/byte_limit for an oversized single line")
+		budgetedOutput = newHeadTailOutputBudgetBuilder(readOutputBudgetBytes, "use offset/limit to request a smaller line range")
 	}
 	budgetedOutput.WriteString(header)
 	budgetedOutput.WriteString("\n")
@@ -224,9 +249,9 @@ func renderReadFileRange(absolutePath string, relativePath string, total int, st
 	}
 	if truncated {
 		// The Truncated flag alone is invisible to the model in the rendered
-		// output, so it cannot tell a max_lines cut from a complete read. Make the
+		// output, so it cannot tell a limit cut from a complete read. Make the
 		// cut explicit and tell it how to continue.
-		budgetedOutput.WriteString(fmt.Sprintf("\n\n[truncated: %d more line(s) in the requested range not shown; set start_line=%d to continue]", endLine-lastLine, lastLine+1))
+		budgetedOutput.WriteString(fmt.Sprintf("\n\n[truncated: %d more line(s) in the requested range not shown; set offset=%d to continue]", endLine-lastLine, lastLine+1))
 	}
 
 	budgeted := budgetedOutput.Result()
@@ -241,7 +266,7 @@ func renderReadFileRange(absolutePath string, relativePath string, total int, st
 		if budgeted.Truncated {
 			meta["truncation_reason"] = "byte_budget"
 		} else {
-			meta["truncation_reason"] = "max_lines"
+			meta["truncation_reason"] = "limit"
 		}
 	}
 	return Result{

internal/tools/read_minified_file.go

@@ -28,12 +28,13 @@ func NewScopedReadMinifiedFileTool(workspaceRoot string, scope PathScope) Tool {
 	return readMinifiedFileTool{
 		baseTool: baseTool{
 			name:        "read_minified_file",
-			description: "Read a source file in a dense, token-cheap form: comments and redundant whitespace removed, no line numbers. Use it to scan or understand code for far fewer tokens than read_file. For exact text, comments, line numbers, or before editing, use read_file instead.",
-			deferred:    true,
+			description: "Read source code in a token-efficient, language-aware form. Prefer this for initial understanding; use read_file for exact text or line numbers.",
 			parameters: Schema{
 				Type: "object",
 				Properties: map[string]PropertySchema{
-					"path": {Type: "string", Description: "Path of the file to read in minified form."},
+					"path":   {Type: "string", Description: "Source file path."},
+					"offset": {Type: "integer", Description: "Optional 1-based source line to start from.", Minimum: intPtr(1)},
+					"limit":  {Type: "integer", Description: "Optional maximum number of source lines to minify.", Minimum: intPtr(1)},
 				},
 				Required:             []string{"path"},
 				AdditionalProperties: false,
@@ -59,6 +60,14 @@ func (tool readMinifiedFileTool) run(args map[string]any, options RunOptions, di
 	if err != nil {
 		return errorResult("Error: Invalid arguments for read_minified_file: " + err.Error())
 	}
+	offset, err := intArg(args, "offset", 1, 1, 0)
+	if err != nil {
+		return errorResult("Error: Invalid arguments for read_minified_file: " + err.Error())
+	}
+	limit, err := intArg(args, "limit", 0, 1, 0)
+	if err != nil {
+		return errorResult("Error: Invalid arguments for read_minified_file: " + err.Error())
+	}
 
 	absolutePath, relativePath, err := resolveScopedReadPath(tool.workspaceRoot, tool.scope, requestedPath)
 	if err != nil {
@@ -75,11 +84,19 @@ func (tool readMinifiedFileTool) run(args map[string]any, options RunOptions, di
 	info, _ := os.Stat(absolutePath)
 	options.FileTracker.Record(absolutePath, content, info)
 
-	result := minify.File(relativePath, content)
-	rawLines := lineCount(string(content))
+	selected := selectSourceLines(content, offset, limit)
+	if selected.pastEnd {
+		return okResult(fmt.Sprintf("File: %s\n(offset %d is past the end of the file, which has %d lines)", relativePath, offset, selected.totalLines))
+	}
+	ranged := offset > 1 || limit > 0
+	result := minify.File(relativePath, selected.content)
+	if ranged {
+		result = minify.ContextualFragment(relativePath, content, selected.content, selected.startByte)
+	}
+	rawLines := lineCount(string(selected.content))
 	minLines := lineCount(result.Content)
 	pct := 0
-	if rawBytes := len(content); rawBytes > 0 {
+	if rawBytes := len(selected.content); rawBytes > 0 {
 		if saved := rawBytes - len(result.Content); saved > 0 {
 			pct = saved * 100 / rawBytes
 		}
@@ -89,12 +106,15 @@ func (tool readMinifiedFileTool) run(args map[string]any, options RunOptions, di
 	if result.Applied {
 		header = fmt.Sprintf("File: %s — minified %s view (comments stripped, no line numbers; %d→%d lines, ~%d%% fewer bytes). For exact text/comments or before editing, use read_file.",
 			relativePath, result.Language, rawLines, minLines, pct)
+	} else if ranged {
+		header = fmt.Sprintf("File: %s — safe ranged view (whitespace normalized, no line numbers; %d→%d lines; context-sensitive stripping disabled because the range may begin inside a multiline construct). For exact text, use read_file.",
+			relativePath, rawLines, minLines)
 	} else {
 		header = fmt.Sprintf("File: %s — whitespace-normalized view (no line numbers; %d→%d lines; full minification not available for this file type). For exact text, use read_file.",
 			relativePath, rawLines, minLines)
 	}
 
-	rawBytes := len(content)
+	rawBytes := len(selected.content)
 	compactBytes := len(result.Content)
 	savedTokens := 0
 	if savedBytes := rawBytes - compactBytes; savedBytes > 0 {
@@ -113,11 +133,54 @@ func (tool readMinifiedFileTool) run(args map[string]any, options RunOptions, di
 	meta["estimated_tokens_saved"] = strconv.Itoa(savedTokens)
 	toolResult := Result{Status: StatusOK, Output: output, Meta: meta}
 	if directBudget {
-		return applyLegacyByteBudgetToResult(toolResult, readOutputBudgetBytes, "use read_file with start_line/end_line or max_lines for normal files, or byte_offset/byte_limit for an oversized single line")
+		return applyLegacyByteBudgetToResult(toolResult, readOutputBudgetBytes, "use offset/limit to request a smaller source range, or read_file when exact text is required")
 	}
 	return toolResult
 }
 
+type sourceSelection struct {
+	content    []byte
+	startByte  int
+	totalLines int
+	pastEnd    bool
+}
+
+func selectSourceLines(content []byte, offset, limit int) sourceSelection {
+	if offset <= 1 && limit == 0 {
+		return sourceSelection{content: content, totalLines: sourceLineCount(content)}
+	}
+	lines := strings.Split(string(content), "\n")
+	totalLines := sourceLineCount(content)
+	start := offset - 1
+	if start >= totalLines {
+		return sourceSelection{startByte: len(content), totalLines: totalLines, pastEnd: true}
+	}
+	startByte := 0
+	for index := 0; index < start; index++ {
+		startByte += len(lines[index]) + 1
+	}
+	end := totalLines
+	if limit > 0 && limit < end-start {
+		end = start + limit
+	}
+	return sourceSelection{
+		content:    []byte(strings.Join(lines[start:end], "\n")),
+		startByte:  startByte,
+		totalLines: totalLines,
+	}
+}
+
+func sourceLineCount(content []byte) int {
+	if len(content) == 0 {
+		return 1
+	}
+	lines := strings.Count(string(content), "\n")
+	if content[len(content)-1] != '\n' {
+		lines++
+	}
+	return lines
+}
+
 // lineCount reports the number of newline-separated lines in s (an empty string
 // counts as 0 lines, matching how a reader perceives an empty file).
 func lineCount(s string) int {

internal/tools/read_minified_file_test.go

@@ -45,6 +45,123 @@ func TestReadMinifiedFileRejectsTraversal(t *testing.T) {
 	}
 }
 
+func TestReadMinifiedFileSelectsSourceLineRangeBeforeMinifying(t *testing.T) {
+	dir := t.TempDir()
+	src := "package demo\n\nfunc One() int { return 1 }\n\nfunc Two() int { return 2 }\n"
+	if err := os.WriteFile(filepath.Join(dir, "f.go"), []byte(src), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	res := NewScopedReadMinifiedFileTool(dir, nil).Run(context.Background(), map[string]any{
+		"path": "f.go", "offset": 5, "limit": 1,
+	})
+	if res.Status != StatusOK || !strings.Contains(res.Output, "func Two") || strings.Contains(res.Output, "func One") {
+		t.Fatalf("unexpected ranged compact read: status=%s\n%s", res.Status, res.Output)
+	}
+}
+
+func TestReadMinifiedFileRangesPreserveUnknownLexicalContext(t *testing.T) {
+	tests := []struct {
+		name string
+		path string
+		src  string
+		want []string
+	}{
+		{
+			name: "multiline string",
+			path: "snippet.py",
+			src:  "value = \"\"\"\n# literal text\nstill literal\n\"\"\"\nprint(value)\n",
+			want: []string{"# literal text", "still literal"},
+		},
+		{
+			name: "template literal",
+			path: "snippet.js",
+			src:  "const value = `\n// literal text\nstill literal\n`;\n",
+			want: []string{"// literal text", "still literal"},
+		},
+		{
+			name: "block comment",
+			path: "snippet.c",
+			src:  "/* open\ncomment body\n*/\nint live;\n",
+			want: []string{"comment body", "*/"},
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			dir := t.TempDir()
+			if err := os.WriteFile(filepath.Join(dir, tc.path), []byte(tc.src), 0o644); err != nil {
+				t.Fatal(err)
+			}
+			res := NewScopedReadMinifiedFileTool(dir, nil).Run(context.Background(), map[string]any{
+				"path": tc.path, "offset": 2, "limit": 2,
+			})
+			if res.Status != StatusOK || res.Meta["compacted"] != "false" {
+				t.Fatalf("ranged read must use conservative normalization: status=%s meta=%#v\n%s", res.Status, res.Meta, res.Output)
+			}
+			for _, want := range tc.want {
+				if !strings.Contains(res.Output, want) {
+					t.Fatalf("ranged read lost lexical content %q:\n%s", want, res.Output)
+				}
+			}
+		})
+	}
+}
+
+func TestReadMinifiedFileRangeInsideGoRawStringIsConservative(t *testing.T) {
+	dir := t.TempDir()
+	src := "package demo\nvar value = `first\nSECRET-MARKER-ONE\n// literal line\nlast`\n"
+	if err := os.WriteFile(filepath.Join(dir, "f.go"), []byte(src), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	res := NewScopedReadMinifiedFileTool(dir, nil).Run(context.Background(), map[string]any{
+		"path": "f.go", "offset": 3, "limit": 2,
+	})
+	if res.Status != StatusOK || res.Meta["compacted"] != "false" {
+		t.Fatalf("raw-string range must use conservative normalization: status=%s meta=%#v\n%s", res.Status, res.Meta, res.Output)
+	}
+	for _, want := range []string{"SECRET-MARKER-ONE", "// literal line"} {
+		if !strings.Contains(res.Output, want) {
+			t.Fatalf("raw-string range lost or rewrote %q:\n%s", want, res.Output)
+		}
+	}
+	if strings.Contains(res.Output, "SECRET - MARKER - ONE") {
+		t.Fatalf("raw-string contents were parsed as Go code:\n%s", res.Output)
+	}
+}
+
+func TestReadMinifiedFileCanonicalOffsetPastEnd(t *testing.T) {
+	dir := t.TempDir()
+	if err := os.WriteFile(filepath.Join(dir, "f.go"), []byte("package demo\nvar value = 1\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	res := NewScopedReadMinifiedFileTool(dir, nil).Run(context.Background(), map[string]any{
+		"path": "f.go", "offset": 10,
+	})
+	if res.Status != StatusOK || !strings.Contains(res.Output, "offset 10 is past the end") {
+		t.Fatalf("expected canonical out-of-range response, got status=%s output=%q", res.Status, res.Output)
+	}
+}
+
+func TestReadMinifiedFileMaximumLimitDoesNotOverflow(t *testing.T) {
+	dir := t.TempDir()
+	if err := os.WriteFile(filepath.Join(dir, "notes.txt"), []byte("alpha\nbeta\ngamma\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	const maxInt = int(^uint(0) >> 1)
+
+	res := NewScopedReadMinifiedFileTool(dir, nil).Run(context.Background(), map[string]any{
+		"path": "notes.txt", "offset": 2, "limit": maxInt,
+	})
+	if res.Status != StatusOK {
+		t.Fatalf("maximum limit should return the remaining range without panicking: status=%s output=%q", res.Status, res.Output)
+	}
+	if !strings.Contains(res.Output, "beta") || !strings.Contains(res.Output, "gamma") || strings.Contains(res.Output, "alpha") {
+		t.Fatalf("maximum limit returned the wrong range: %q", res.Output)
+	}
+}
+
 func TestReadMinifiedFileAppliesByteBudget(t *testing.T) {
 	dir := t.TempDir()
 	if err := os.WriteFile(filepath.Join(dir, "large.txt"), []byte(strings.Repeat("0123456789abcdef\n", 9000)), 0o644); err != nil {

internal/tools/registry.go

@@ -297,8 +297,8 @@ func scrubResultSecrets(res Result) Result {
 
 func CoreReadOnlyToolsScoped(workspaceRoot string, scope PathScope) []Tool {
 	return []Tool{
-		NewScopedReadFileTool(workspaceRoot, scope),
 		NewScopedReadMinifiedFileTool(workspaceRoot, scope),
+		NewScopedReadFileTool(workspaceRoot, scope),
 		// view_image is read-only and shares read_file's path scoping, so it
 		// belongs with the other readers rather than behind a gate.
 		NewScopedViewImageTool(workspaceRoot, scope),

internal/tools/registry_test.go

@@ -523,25 +523,24 @@ func TestIsDeferralEligibleDecouplesFromDeferred(t *testing.T) {
 
 func TestOptionalBuiltinsUseDeferredDiscovery(t *testing.T) {
 	wantDeferred := map[string]bool{
-		"bash":               true,
-		"browser_action":     true,
-		"browser_click":      true,
-		"browser_connect":    true,
-		"browser_install":    true,
-		"browser_launch":     true,
-		"browser_open":       true,
-		"browser_press":      true,
-		"browser_snapshot":   true,
-		"browser_type":       true,
-		"capture_artifact":   true,
-		"desktop_action":     true,
-		"desktop_snapshot":   true,
-		"desktop_windows":    true,
-		"lsp_navigate":       true,
-		"read_minified_file": true,
-		"terminal_session":   true,
-		"web_fetch":          true,
-		"web_search":         true,
+		"bash":             true,
+		"browser_action":   true,
+		"browser_click":    true,
+		"browser_connect":  true,
+		"browser_install":  true,
+		"browser_launch":   true,
+		"browser_open":     true,
+		"browser_press":    true,
+		"browser_snapshot": true,
+		"browser_type":     true,
+		"capture_artifact": true,
+		"desktop_action":   true,
+		"desktop_snapshot": true,
+		"desktop_windows":  true,
+		"lsp_navigate":     true,
+		"terminal_session": true,
+		"web_fetch":        true,
+		"web_search":       true,
 	}
 	for _, tool := range BuiltinCatalog(t.TempDir()) {
 		if _, listed := wantDeferred[tool.Name()]; listed {
@@ -549,7 +548,7 @@ func TestOptionalBuiltinsUseDeferredDiscovery(t *testing.T) {
 				t.Errorf("%s should be deferred", tool.Name())
 			}
 			delete(wantDeferred, tool.Name())
-		} else if tool.Name() == "read_file" || tool.Name() == "grep" || tool.Name() == ExecCommandToolName || tool.Name() == "edit_file" {
+		} else if tool.Name() == "read_file" || tool.Name() == "read_minified_file" || tool.Name() == "grep" || tool.Name() == ExecCommandToolName || tool.Name() == "edit_file" {
 			if IsDeferred(tool) {
 				t.Errorf("essential tool %s must stay eager", tool.Name())
 			}

internal/tools/update_plan.go

@@ -26,7 +26,7 @@ func NewUpdatePlanTool() *updatePlanTool {
 	return &updatePlanTool{
 		baseTool: baseTool{
 			name: "update_plan",
-			description: "Create or update the in-memory plan for the current task. " +
+			description: "Create or update the in-memory plan for implementation or investigation with at least three meaningful dependent steps. Do not use it for simple lookups, explanations, or code navigation. " +
 				"Pass the full ordered list of steps each call; it replaces the previous plan. " +
 				"Each item needs a `content` string; `status` defaults to \"pending\" and `id` is " +
 				"auto-numbered, so you only need to supply `content` (and `status` as the task progresses). " +

internal/tui/session_controls.go

@@ -21,6 +21,7 @@ import (
 var responseStyles = []string{"balanced", "concise", "explanatory", "review"}
 
 const tuiCompactionPreserveLast = 8
+const tuiCompactionMaxPromptChars = 8000
 const compactStatusRowID = "compact/status"
 
 var compactFrames = []string{"⠂", "⠒", "⠲", "⠴"}
@@ -841,8 +842,8 @@ func (m model) compactActiveSession() (model, CompactResult, error) {
 	beforeEvents := append([]sessions.Event{}, m.sessionEvents...)
 	beforeTokens := estimateTranscriptTokens(m.transcript)
 	plan, err := m.sessionStore.PlanCompaction(m.activeSession.SessionID, sessions.CompactionOptions{
-		PreserveLast: tuiCompactionPreserveLast,
-		SkipPrompt:   true,
+		PreserveLast:   tuiCompactionPreserveLast,
+		MaxPromptChars: tuiCompactionMaxPromptChars,
 	})
 	if err != nil {
 		return m, CompactResult{}, err
@@ -856,26 +857,13 @@ func (m model) compactActiveSession() (model, CompactResult, error) {
 		}, nil
 	}
 
-	rawEvents, err := m.sessionStore.ReadEvents(m.activeSession.SessionID)
-	if err != nil {
-		return m, CompactResult{}, fmt.Errorf("read session events for compaction: %w", err)
-	}
-	compactableEvents, err := sessionEventsForRefs(rawEvents, plan.CompactableEvents)
+	summary, err := m.summarizeCompactionPlan(plan)
 	if err != nil {
 		return m, CompactResult{}, err
 	}
-	summaryResult, err := m.summarizeCompactionPlan(plan, sessions.CompactionMessages(compactableEvents))
-	if err != nil {
-		return m, CompactResult{}, err
-	}
-	// PromptChars counts the text content sent to the provider: the shared
-	// system instruction plus projected message/tool payloads. Provider protocol
-	// framing is intentionally excluded.
-	plan.PromptChars = len(agent.CompactionSummaryInstructions) + summaryResult.ProjectedChars
-	plan.Truncated = summaryResult.Truncated
 	if _, err := m.sessionStore.RecordCompaction(m.activeSession.SessionID, sessions.RecordCompactionInput{
 		Plan:    plan,
-		Summary: summaryResult.SummaryText,
+		Summary: summary,
 	}); err != nil {
 		return m, CompactResult{}, err
 	}
@@ -897,47 +885,32 @@ func (m model) compactActiveSession() (model, CompactResult, error) {
 		Compacted:    len(events) < len(beforeEvents)+1,
 		BeforeTokens: beforeTokens,
 		AfterTokens:  estimateTranscriptTokens(m.transcript),
-		Summary:      summaryResult.SummaryText,
+		Summary:      summary,
 	}, nil
 }
 
-func sessionEventsForRefs(events []sessions.Event, refs []sessions.EventRef) ([]sessions.Event, error) {
-	byID := make(map[string]sessions.Event, len(events))
-	for _, event := range events {
-		byID[event.ID] = event
+func (m model) summarizeCompactionPlan(plan sessions.CompactionPlan) (string, error) {
+	if m.provider == nil {
+		return deterministicCompactionSummary(plan), nil
 	}
-	selected := make([]sessions.Event, 0, len(refs))
-	for _, ref := range refs {
-		event, ok := byID[ref.ID]
-		if !ok || event.Sequence != ref.Sequence || event.Type != ref.Type {
-			return nil, fmt.Errorf("session changed while compaction was being planned; retry /compact")
-		}
-		selected = append(selected, event)
-	}
-	return selected, nil
-}
-
-func (m model) summarizeCompactionPlan(plan sessions.CompactionPlan, messages []zeroruntime.Message) (agent.CompactionSummaryResult, error) {
-	return agent.SummarizeCompactionMessages(messages, func(projected []zeroruntime.Message) (string, error) {
-		if m.provider == nil {
-			return deterministicCompactionSummary(plan), nil
-		}
-		stream, streamErr := m.provider.StreamCompletion(m.ctx, zeroruntime.CompletionRequest{
-			Messages: append([]zeroruntime.Message{{Role: zeroruntime.MessageRoleSystem, Content: agent.CompactionSummaryInstructions}}, projected...),
-		})
-		if streamErr != nil {
-			return "", fmt.Errorf("summarize compacted session: %w", streamErr)
-		}
-		collected := zeroruntime.CollectStream(m.ctx, stream)
-		if collected.Error != "" {
-			return "", fmt.Errorf("summarize compacted session: %s", collected.Error)
-		}
-		result := strings.TrimSpace(collected.Text)
-		if result == "" {
-			return "", fmt.Errorf("summarize compacted session: empty summary")
-		}
-		return result, nil
+	stream, err := m.provider.StreamCompletion(m.ctx, zeroruntime.CompletionRequest{
+		Messages: []zeroruntime.Message{
+			{Role: zeroruntime.MessageRoleSystem, Content: "Summarize compacted Zero session events for future coding context. Preserve user goals, decisions, files, tool outcomes, blockers, and exact next steps. Omit secrets and do not invent details."},
+			{Role: zeroruntime.MessageRoleUser, Content: plan.SummaryPrompt},
+		},
 	})
+	if err != nil {
+		return "", fmt.Errorf("summarize compacted session: %w", err)
+	}
+	collected := zeroruntime.CollectStream(m.ctx, stream)
+	if collected.Error != "" {
+		return "", fmt.Errorf("summarize compacted session: %s", collected.Error)
+	}
+	summary := strings.TrimSpace(collected.Text)
+	if summary == "" {
+		return "", fmt.Errorf("summarize compacted session: empty summary")
+	}
+	return summary, nil
 }
 
 func deterministicCompactionSummary(plan sessions.CompactionPlan) string {

internal/tui/session_controls_test.go

@@ -481,15 +481,6 @@ func TestCompactCommandUsesProviderSummaryWhenAvailable(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	for _, input := range []sessions.AppendEventInput{
-		{Type: sessions.EventToolCall, Payload: map[string]any{"id": "ask", "name": "ask_user", "arguments": `{"questions":[{"question":"Which database should remain?"}]}`}},
-		{Type: sessions.EventToolResult, Payload: map[string]any{"toolCallId": "ask", "name": "ask_user", "status": "ok", "output": "Postgres only"}},
-	} {
-		m, err = m.appendSessionEvent(input.Type, input.Payload)
-		if err != nil {
-			t.Fatal(err)
-		}
-	}
 	for _, content := range []string{
 		"old decision A",
 		"old decision B",
@@ -530,15 +521,6 @@ func TestCompactCommandUsesProviderSummaryWhenAvailable(t *testing.T) {
 	if len(provider.requests) != 1 {
 		t.Fatalf("expected one provider summarization request, got %d", len(provider.requests))
 	}
-	request := provider.requests[0]
-	if len(request.Messages) != 2 || request.Messages[0].Content != agent.CompactionSummaryInstructions {
-		t.Fatalf("manual compaction did not use the shared agent compaction prompt: %#v", request.Messages)
-	}
-	for _, want := range []string{"Which database should remain?", "Postgres only"} {
-		if !strings.Contains(request.Messages[1].Content, want) {
-			t.Fatalf("manual compaction projection lost %q: %q", want, request.Messages[1].Content)
-		}
-	}
 	if next.lastCompactResult == nil || next.lastCompactResult.Summary != "Provider summary keeps the actual old decisions." {
 		t.Fatalf("expected provider summary result, got %#v", next.lastCompactResult)
 	}
@@ -551,56 +533,6 @@ func TestCompactCommandUsesProviderSummaryWhenAvailable(t *testing.T) {
 	}
 }
 
-func TestManualCompactionPersistsStructuralTruncationMetadata(t *testing.T) {
-	store := sessions.NewStore(sessions.StoreOptions{RootDir: t.TempDir()})
-	provider := &fakeProvider{events: []zeroruntime.StreamEvent{
-		{Type: zeroruntime.StreamEventText, Content: "Bounded summary."},
-		{Type: zeroruntime.StreamEventDone},
-	}}
-	m := newModel(context.Background(), Options{ModelName: "gpt-4.1", Provider: provider, SessionStore: store})
-	var err error
-	m, err = m.ensureActiveSession("compact a large session")
-	if err != nil {
-		t.Fatal(err)
-	}
-	for index := range 20 {
-		content := strings.Repeat("contextword ", 256) + string(rune('a'+index))
-		m, err = m.appendSessionEvent(sessions.EventMessage, map[string]any{"role": "user", "content": content})
-		if err != nil {
-			t.Fatal(err)
-		}
-		m.transcript = appendTranscriptRow(m.transcript, transcriptRow{kind: rowUser, text: content})
-	}
-
-	next, result, err := m.compactActiveSession()
-	if err != nil || !result.Compacted {
-		t.Fatalf("compactActiveSession() = (%#v, %v)", result, err)
-	}
-	raw, err := store.ReadEvents(next.activeSession.SessionID)
-	if err != nil {
-		t.Fatal(err)
-	}
-	latest := raw[len(raw)-1]
-	if latest.Type != sessions.EventCompaction {
-		t.Fatalf("latest event = %s, want compaction", latest.Type)
-	}
-	payload := sessionPayload(latest)
-	if !payloadBool(payload, "truncated") {
-		t.Fatalf("compaction did not persist structural truncation: %#v", payload)
-	}
-	request := provider.requests[0]
-	wantPromptChars := len(agent.CompactionSummaryInstructions)
-	for _, message := range request.Messages[1:] {
-		wantPromptChars += len(message.Content)
-		for _, call := range message.ToolCalls {
-			wantPromptChars += len(call.Name) + len(call.Arguments)
-		}
-	}
-	if promptChars, ok := payload["promptChars"].(float64); !ok || int(promptChars) != wantPromptChars {
-		t.Fatalf("promptChars = %#v, want %d", payload["promptChars"], wantPromptChars)
-	}
-}
-
 func TestCompactCommandRecordsRequestWhenNoCompactorIsAvailable(t *testing.T) {
 	m := newModel(context.Background(), Options{})
 	m.input.SetValue("/compact")

internal/zeroruntime/types.go

@@ -93,14 +93,12 @@ type ReasoningBlock struct {
 
 // Message is a normalized conversation turn passed to providers.
 type Message struct {
-	Role         MessageRole
-	Content      string
-	ToolCalls    []ToolCall
-	ToolCallID   string
-	IsError      bool             // tool-result status; ignored for non-tool messages
-	ChangedFiles []string         // durable tool-result mutation targets; ignored by providers
-	Images       []ImageBlock     // optional; nil for text-only messages
-	Reasoning    []ReasoningBlock // optional; preserved thinking blocks to replay
+	Role       MessageRole
+	Content    string
+	ToolCalls  []ToolCall
+	ToolCallID string
+	Images     []ImageBlock     // optional; nil for text-only messages
+	Reasoning  []ReasoningBlock // optional; preserved thinking blocks to replay
 }
 
 // ToolDefinition describes a model-visible tool and its JSON-schema parameters.