fix(proxydial): bind the proxy exemption to the route the transport chose

Asking the Proxy function a question of our own invention answered for a
request the transport never made. With NO_PROXY excluding a host, the real
request to that host goes direct while a synthetic probe still comes back
proxied, so a direct dial whose address happened to equal the configured
proxy endpoint skipped the guard and reached whatever the name resolved to
at connect time. A probe on the previous head dials rebind.example:80 with
zero safety lookups; the guard now runs and refuses its private answer.
Host-dependent proxy callbacks make the mismatch general, and no spelling
of the probe host closes it, because the two calls are about different
requests.

The decision is now recorded where it is made. proxydial.Transport wraps
the transport, asks its Proxy function about the actual request, and puts
the answer in that request's context; the transport derives the dial
context from the request context, so the dialer reads back the route this
very connection is being opened for. Per-request, so concurrent requests
cannot overwrite each other, and the context key is unexported so nothing
outside the package can plant one.

Address matching is gone with it. A transport opens one connection dial,
and when a proxy is selected that dial goes to the proxy, so the recorded
route already identifies the dial. Comparing the address on top could only
disagree with the transport, which is what a Unicode proxy hostname did:
Go dials xn--bro-hoa.example while the URL still spells it as configured,
and the proxy was refused as an ordinary private address. Both spellings
are now one endpoint with no comparison to get wrong.

Documents where destination enforcement ends: with a proxy configured, the
target hostname is sent to the proxy and the proxy resolves it, so the
local pre-request checks no longer bind the address that is reached. A
forward proxy already sees and can rewrite every request through it, so
that trust comes with configuring one; the alternative is refusing to use
proxies at all, which is the outage in #569.

README.md

@@ -273,6 +273,19 @@ zero sandbox grants list
 Zero includes local file/search/edit/shell tools, `web_fetch` for public URLs,
 and MCP support for additional tools.
 
+`web_fetch` refuses loopback, private and other special-use addresses: it checks
+the URL before asking permission, resolves the host, and dials the address it
+validated so a name cannot resolve to something else in between.
+
+If `HTTP_PROXY`/`HTTPS_PROXY` is set, `web_fetch` and the provider connectivity
+probe use it, and that last step changes: the proxy is dialed and the target
+hostname is sent to it, so the proxy decides which address the request actually
+reaches. The URL is still checked and resolved locally first, but a proxy that
+answers differently can reach a private service. A forward proxy already sees
+and can rewrite every request through it, so this is the trust you accept by
+configuring one. Leave the variables unset for the checks to be enforced end to
+end.
+
 For local dev servers, use shell commands such as `curl` through `exec_command`
 so the normal sandbox and permission policy applies. Long-running commands stay
 attached to a background terminal session and can be listed or stopped from the

docs/HOW_ZERO_WORKS.md

@@ -627,7 +627,12 @@ Core tool groups include:
   skills, `ask_user`, permission requests.
 - **Write tools**: `write_file`, `edit_file`, `apply_patch`, `update_plan`.
 - **Shell tools**: `exec_command`, `write_stdin`, legacy `bash`.
-- **Network tools**: `web_fetch` and optional web search backend.
+- **Network tools**: `web_fetch` and optional web search backend. `web_fetch`
+  validates the URL before the permission prompt, refuses loopback/private/
+  special-use addresses, and dials the address it resolved. With
+  `HTTP_PROXY`/`HTTPS_PROXY` set, the proxy is dialed instead and resolves the
+  target itself, so destination enforcement ends at the proxy; see the note in
+  the README.
 - **Local-control tools**: config-gated wrappers for browser, terminal, desktop,
   and artifact helpers backed by packages such as `internal/localcontrol` and
   `internal/browser`.

internal/cli/app.go

@@ -311,35 +311,40 @@ func runWithDeps(args []string, stdout io.Writer, stderr io.Writer, deps appDeps
 	// cache file on the machine. The refresh itself is fired in exec/TUI startup.
 	modelregistry.EnableModelsDevOverlay()
 
-	// --add-dir, --theme and --allow-escalation may be written in any order;
-	// see splitLeadingRootFlags for why they are split together.
-	root, args, err := splitLeadingRootFlags(args)
+	addDirs, args, err := splitLeadingAddDirFlags(args)
 	if err != nil {
 		return writeAppError(stderr, err.Error(), 1)
 	}
-	addDirs, theme, allowEscalation := root.addDirs, root.theme, root.allowEscalation
+	// --theme <name> selects the TUI palette non-interactively (auto or any registered
+	// theme; populates tui.Options.Theme, which resolveThemeMode prefers over
+	// ZERO_THEME). Re-split --add-dir afterward so it may appear on either side of --theme.
+	theme, args, err := splitLeadingThemeFlag(args)
+	if err != nil {
+		return writeAppError(stderr, err.Error(), 1)
+	}
+	moreDirs, args, err := splitLeadingAddDirFlags(args)
+	if err != nil {
+		return writeAppError(stderr, err.Error(), 1)
+	}
+	addDirs = append(addDirs, moreDirs...)
 
 	if len(args) == 0 {
-		return runInteractiveTUI(stderr, deps, agent.PermissionModeAsk, addDirs, theme, allowEscalation)
+		return runInteractiveTUI(stderr, deps, agent.PermissionModeAsk, addDirs, theme)
 	}
 
-	// --add-dir grants an extra write root and --allow-escalation opts a run
-	// into mid-run model escalation; only the interactive TUI and exec consume
-	// either. Both are forwarded to exec below and rejected loudly everywhere
-	// else rather than silently discarded, including help/version, which run
-	// no agent and could only ignore them. The allowlist names exactly the
-	// cases below that forward; a future subcommand is rejected by default
-	// until it opts in here.
-	forwardsRootFlags := false
-	switch args[0] {
-	case "--skip-permissions-unsafe", "-p", "--prompt", "exec":
-		forwardsRootFlags = true
-	}
-	if len(addDirs) > 0 && !forwardsRootFlags {
-		return writeAppError(stderr, "--add-dir is only supported for the interactive TUI and exec", 1)
-	}
-	if allowEscalation && !forwardsRootFlags {
-		return writeAppError(stderr, "--allow-escalation is only supported for the interactive TUI and exec", 1)
+	// --add-dir grants an extra write root, and only the interactive TUI and
+	// exec dispatch paths consume one. Fail loud everywhere else rather than
+	// silently discarding an explicit grant — including help/version, which
+	// run no agent and could only ignore it. The allowlist names exactly the
+	// cases below that forward addDirs; a future subcommand is rejected by
+	// default until it opts in here.
+	if len(addDirs) > 0 {
+		switch args[0] {
+		case "--skip-permissions-unsafe", "-p", "--prompt", "exec":
+			// Forwarded by the matching case below.
+		default:
+			return writeAppError(stderr, "--add-dir is only supported for the interactive TUI and exec", 1)
+		}
 	}
 
 	switch args[0] {
@@ -349,24 +354,26 @@ func runWithDeps(args []string, stdout io.Writer, stderr io.Writer, deps appDeps
 		// reach unsafe mode in the shell — and the "!" shell escape (which is
 		// gated behind unsafe) was therefore unreachable.
 		//
-		// The root flags may legally appear on either side of this flag, so
-		// split them again from what follows it and merge with what the root
-		// already took. Any trailing non-flag args were ignored on this path
-		// before --add-dir existed and still are, but an --add-dir hidden
-		// BEHIND one would be silently dropped with them, so reject that
-		// misplacement loudly below.
-		more, rest, err := splitLeadingRootFlags(args[1:])
+		// --add-dir may legally appear on either side of the flag, so re-split
+		// the remaining args and merge with the dirs already collected. Any
+		// trailing non-flag args were ignored on this path before --add-dir
+		// existed and still are — but an --add-dir hidden BEHIND one would be
+		// silently dropped with them, so reject that misplacement loudly.
+		moreDirs, rest, err := splitLeadingAddDirFlags(args[1:])
 		if err != nil {
 			return writeAppError(stderr, err.Error(), 1)
 		}
-		moreDirs := more.addDirs
-		// A --theme written before the flag was taken at the root and used to be
-		// dropped here; one written after it wins, as the last occurrence does.
-		skipTheme := theme
-		if more.theme != "" {
-			skipTheme = more.theme
+		// --theme may appear here too; extract it before the stray-arg checks so it is
+		// not rejected as an unexpected positional, then re-split --add-dir after it.
+		skipTheme, rest, err := splitLeadingThemeFlag(rest)
+		if err != nil {
+			return writeAppError(stderr, err.Error(), 1)
 		}
-		skipAllowEscalation := more.allowEscalation
+		evenMoreDirs, rest, err := splitLeadingAddDirFlags(rest)
+		if err != nil {
+			return writeAppError(stderr, err.Error(), 1)
+		}
+		moreDirs = append(moreDirs, evenMoreDirs...)
 		// A misplaced --add-dir anywhere in the remainder is the more specific error,
 		// so check for it across all of rest before rejecting stray args.
 		for _, arg := range rest {
@@ -383,7 +390,7 @@ func runWithDeps(args []string, stdout io.Writer, stderr io.Writer, deps appDeps
 				return writeAppError(stderr, "--skip-permissions-unsafe launches the interactive TUI and takes no prompt or subcommand; for a one-shot unsafe run use `zero exec --skip-permissions-unsafe -p \"...\"`", 1)
 			}
 		}
-		return runInteractiveTUI(stderr, deps, agent.PermissionModeUnsafe, append(append([]string{}, addDirs...), moreDirs...), skipTheme, allowEscalation || skipAllowEscalation)
+		return runInteractiveTUI(stderr, deps, agent.PermissionModeUnsafe, append(append([]string{}, addDirs...), moreDirs...), skipTheme)
 	case "-h", "--help", "help":
 		if err := writeHelp(stdout); err != nil {
 			return 1
@@ -416,16 +423,16 @@ func runWithDeps(args []string, stdout io.Writer, stderr io.Writer, deps appDeps
 		if len(args) < 2 {
 			return writePromptRequired(stderr)
 		}
-		// Forward the root flags exec consumes so its own parser collects them.
+		// Forward leading --add-dir occurrences so exec's own parser collects them.
 		// Use the inline --prompt=<value> form so a prompt whose first character is a
 		// dash (e.g. `zero -p "-foo"`) is taken verbatim instead of being mistaken for
 		// a flag and rejected with "--prompt requires a value" (matches the cron path).
-		execArgs := append(rootFlagArgs(addDirs, allowEscalation), "--prompt="+args[1])
+		execArgs := append(addDirFlagArgs(addDirs), "--prompt="+args[1])
 		execArgs = append(execArgs, args[2:]...)
 		return runExec(execArgs, stdout, stderr, deps)
 	case "exec":
-		// Forward the root flags exec consumes so its own parser collects them.
-		return runExec(append(rootFlagArgs(addDirs, allowEscalation), args[1:]...), stdout, stderr, deps)
+		// Forward leading --add-dir occurrences so exec's own parser collects them.
+		return runExec(append(addDirFlagArgs(addDirs), args[1:]...), stdout, stderr, deps)
 	case "completions":
 		return runCompletions(args[1:], stdout, stderr)
 	case "daemon":
@@ -687,11 +694,11 @@ func fillAppDeps(deps appDeps) appDeps {
 	return deps
 }
 
-func runInteractiveTUI(stderr io.Writer, deps appDeps, permissionMode agent.PermissionMode, addDirs []string, theme string, allowEscalation bool) int {
-	return runInteractiveTUIWithSetup(stderr, deps, permissionMode, addDirs, theme, false, allowEscalation)
+func runInteractiveTUI(stderr io.Writer, deps appDeps, permissionMode agent.PermissionMode, addDirs []string, theme string) int {
+	return runInteractiveTUIWithSetup(stderr, deps, permissionMode, addDirs, theme, false)
 }
 
-func runInteractiveTUIWithSetup(stderr io.Writer, deps appDeps, permissionMode agent.PermissionMode, addDirs []string, theme string, forceSetup bool, allowEscalation bool) int {
+func runInteractiveTUIWithSetup(stderr io.Writer, deps appDeps, permissionMode agent.PermissionMode, addDirs []string, theme string, forceSetup bool) int {
 	// Refresh the models.dev pricing/limits cache in the background when stale;
 	// the overlay is read at registry construction from the cache file, so this
 	// benefits the next run and never blocks or fails this one.
@@ -783,14 +790,6 @@ func runInteractiveTUIWithSetup(stderr io.Writer, deps appDeps, permissionMode a
 
 	registry := newCoreRegistryScoped(workspaceRoot, scope)
 	registerLocalControlTools(registry, workspaceRoot, resolved.LocalControl)
-	// Mid-run model escalation is opt-in on this surface too. The tool is present
-	// only when the operator asked for it with --allow-escalation, and the
-	// switchers that make it do anything ride on the same flag through
-	// Options.AllowEscalation below. Registering one without the other ships a
-	// tool the loop will never act on, which looks like a feature and is not.
-	if allowEscalation {
-		registry.Register(tools.NewEscalateModelTool())
-	}
 	executionRunner := execution.NewRunner(nil)
 	sandboxStore, err := deps.newSandboxStore()
 	if err != nil {
@@ -1034,7 +1033,6 @@ func runInteractiveTUIWithSetup(stderr io.Writer, deps appDeps, permissionMode a
 			Specialists:    specialistRuntime.specialists,
 			Skills:         pluginActivation.skillInfos(deps.skillsDir()),
 		},
-		AllowEscalation: allowEscalation,
 		// LoadSkills backs /skills and direct /<skill-name> invocation in the TUI.
 		// It resolves against the same merged set (default dir + plugin skill
 		// roots) as the skill tool and the system-prompt list, re-read per use so
@@ -1380,7 +1378,6 @@ Flags:
   -v, --version                  Print version
   -p, --prompt                   Run a one-shot prompt
       --add-dir <path>           Allow writes in an extra directory (repeatable)
-      --allow-escalation         Let the agent escalate to a stronger model mid-run via escalate_model
       --skip-permissions-unsafe  Launch the interactive shell in unsafe mode (enables the ! shell escape)
 `)
 	return err
@@ -1397,17 +1394,6 @@ func addDirFlagArgs(addDirs []string) []string {
 	return flags
 }
 
-// rootFlagArgs re-synthesises the root flags exec consumes, in the spelling
-// its own parser accepts, so a flag written before the subcommand reaches
-// the run exactly as one written after it would.
-func rootFlagArgs(addDirs []string, allowEscalation bool) []string {
-	flags := addDirFlagArgs(addDirs)
-	if allowEscalation {
-		flags = append(flags, "--allow-escalation")
-	}
-	return flags
-}
-
 // splitLeadingAddDirFlags strips leading --add-dir flags from the root
 // argument list (zero --add-dir <path> [--add-dir <path>] [subcommand …]).
 // Subcommands like exec parse their own --add-dir occurrences.
@@ -1448,83 +1434,6 @@ func splitLeadingAddDirFlags(args []string) ([]string, []string, error) {
 	return addDirs, args, nil
 }
 
-// rootFlags is what the leading root flags amount to once every one of them
-// has been stripped from the front of the argument list.
-type rootFlags struct {
-	addDirs         []string
-	theme           string
-	allowEscalation bool
-}
-
-// splitLeadingRootFlags strips --add-dir, --theme and --allow-escalation from
-// the front of args in whatever order they were written, stopping at the
-// first token none of them claims.
-//
-// EACH SPLITTER STOPS AT THE FIRST TOKEN IT DOES NOT OWN, so running them once
-// in a fixed sequence made the order the operator wrote them in load-bearing:
-// a flag handled late in the sequence stranded every flag written after it as
-// an unknown command, and `zero --allow-escalation --theme auto` exited with
-// an argument error instead of launching. Running the sequence until it makes
-// no progress accepts every ordering, including a flag repeated on both sides
-// of another.
-func splitLeadingRootFlags(args []string) (rootFlags, []string, error) {
-	var flags rootFlags
-	for {
-		before := len(args)
-		addDirs, rest, err := splitLeadingAddDirFlags(args)
-		if err != nil {
-			return rootFlags{}, nil, err
-		}
-		flags.addDirs = append(flags.addDirs, addDirs...)
-		theme, rest, err := splitLeadingThemeFlag(rest)
-		if err != nil {
-			return rootFlags{}, nil, err
-		}
-		if theme != "" {
-			// The last occurrence wins across passes, as it does within one.
-			flags.theme = theme
-		}
-		allowEscalation, rest, err := splitLeadingAllowEscalationFlag(rest)
-		if err != nil {
-			return rootFlags{}, nil, err
-		}
-		flags.allowEscalation = flags.allowEscalation || allowEscalation
-		args = rest
-		if len(args) == before {
-			return flags, args, nil
-		}
-	}
-}
-
-// splitLeadingAllowEscalationFlag strips a leading --allow-escalation from the
-// root argument list, opting the interactive session into mid-run model
-// escalation.
-//
-// OPT-IN, THE SAME WAY exec IS. Escalation moves a run onto a different model,
-// which changes what the run costs and which provider sees the conversation, so
-// it is a decision the operator makes rather than a default. The exec flag
-// already answers this conservatively and the interactive surface should not
-// answer it differently.
-//
-// Bare flag only: repeating it is harmless, and an =value form is rejected so a
-// mistyped --allow-escalation=false is a loud error instead of silently enabling
-// the thing it was trying to turn off.
-func splitLeadingAllowEscalationFlag(args []string) (bool, []string, error) {
-	allow := false
-	for len(args) > 0 {
-		switch {
-		case args[0] == "--allow-escalation":
-			allow = true
-			args = args[1:]
-		case strings.HasPrefix(args[0], "--allow-escalation="):
-			return false, nil, errors.New("--allow-escalation takes no value; pass it bare to enable mid-run model escalation, or omit it")
-		default:
-			return allow, args, nil
-		}
-	}
-	return allow, args, nil
-}
-
 // splitLeadingThemeFlag strips a leading --theme <auto|theme-name> (space or =form)
 // from the root argument list and validates it against the registered themes. The
 // last occurrence wins. A value outside the allowed set is a loud error rather than

internal/cli/completions.go

@@ -20,7 +20,7 @@ type completionContext struct {
 }
 
 var completionRoot = completionNode{
-	flags: []string{"-h", "--help", "-v", "--version", "-p", "--prompt", "--add-dir", "--allow-escalation", "--theme", "--skip-permissions-unsafe"},
+	flags: []string{"-h", "--help", "-v", "--version", "-p", "--prompt", "--add-dir", "--theme", "--skip-permissions-unsafe"},
 	children: []completionNode{
 		{names: []string{"exec"}, flags: []string{
 			"-h", "--help", "-f", "--file", "--image", "--add-dir", "--mode", "-m", "--model",

internal/cli/exec.go

@@ -442,22 +442,57 @@ func runExec(args []string, stdout io.Writer, stderr io.Writer, deps appDeps) in
 	// the resolved model and is reassigned by the model switcher on a mid-run
 	// escalation so post-switch turns are attributed to the escalated model.
 	currentModel := resolved.Provider.Model
-	// Optimized OpenAI turn sessions (ZERO_OPENAI_TURN_SESSION, default off). nil
-	// when gated off or the profile is ineligible: agent.Run then wraps the
-	// provider in its default adapter. This is the run's STARTING session provider
-	// and is used whether or not escalation is enabled.
-	turnSessions, _ := providers.OptimizedTurnSessions(resolved.Provider, provider, providers.Options{})
-	// Both switchers come from one shared builder so exec and the interactive TUI
-	// cannot drift on the nil contracts the agent loop depends on. The session
-	// switcher is nil unless this run STARTED optimized, which is what keeps a
-	// default-adapter run on the default adapter.
 	var modelSwitcher func(context.Context, string) (agent.Provider, error)
-	var modelSessionSwitcher func(context.Context, string) (zeroruntime.TurnSessionProvider, error)
 	if options.allowEscalation {
-		modelSwitcher, modelSessionSwitcher = providers.EscalationSwitchers(
-			resolved.Provider, provider, deps.newProvider,
-			func(modelID string) { currentModel = modelID },
-		)
+		modelSwitcher = func(_ context.Context, modelID string) (agent.Provider, error) {
+			// deps.newProvider is wrapped (fillAppDeps) to apply the stored key, so
+			// the escalated provider is authenticated even though resolved.Provider
+			// is the pure profile — no per-site key handling here.
+			switchedProfile := resolved.Provider
+			switchedProfile.Model = modelID
+			switchedProvider, err := deps.newProvider(switchedProfile)
+			if err != nil {
+				return nil, err
+			}
+			// Mirror the agent loop's switch guard (it only reassigns the provider
+			// when newProvider != nil). Updating currentModel only on a non-nil
+			// provider keeps usage attribution consistent with whether the loop
+			// actually switched — a (nil, nil) return leaves both untouched.
+			if switchedProvider != nil {
+				currentModel = modelID
+			}
+			return switchedProvider, nil
+		}
+	}
+
+	// Optimized OpenAI turn sessions (ZERO_OPENAI_TURN_SESSION, default off).
+	// nil when gated off or the profile is ineligible: agent.Run then wraps the
+	// provider in its default adapter — the exact code path of today. The
+	// session switcher is installed only when the run START is optimized, so
+	// the legacy ModelSwitcher path above stays untouched otherwise.
+	turnSessions, _ := providers.OptimizedTurnSessions(resolved.Provider, provider, providers.Options{})
+	var modelSessionSwitcher func(context.Context, string) (zeroruntime.TurnSessionProvider, error)
+	if options.allowEscalation && turnSessions != nil {
+		modelSessionSwitcher = func(_ context.Context, modelID string) (zeroruntime.TurnSessionProvider, error) {
+			switchedProfile := resolved.Provider
+			switchedProfile.Model = modelID
+			switchedProvider, err := deps.newProvider(switchedProfile)
+			if err != nil {
+				return nil, err
+			}
+			if switchedProvider == nil {
+				// The loop treats a nil session source as "no swap" — mirror the
+				// legacy closure's (nil, nil) contract.
+				return nil, nil
+			}
+			currentModel = modelID
+			if optimized, ok := providers.OptimizedTurnSessions(switchedProfile, switchedProvider, providers.Options{}); ok {
+				return optimized, nil
+			}
+			// Ineligible switch target: default adapter, but with the switched
+			// model's resolved capability projection preserved.
+			return providers.DefaultTurnSessions(switchedProfile, switchedProvider, providers.Options{}), nil
+		}
 	}
 
 	runMetadata, err := resolveExecRunMetadata(resolved.Provider)

internal/cli/root_flag_order_test.go

@@ -1,211 +0,0 @@
-package cli
-
-import (
-	"bytes"
-	"context"
-	"path/filepath"
-	"strings"
-	"testing"
-
-	"github.com/Gitlawb/zero/internal/agent"
-	"github.com/Gitlawb/zero/internal/config"
-	"github.com/Gitlawb/zero/internal/sandbox"
-	"github.com/Gitlawb/zero/internal/tui"
-	"github.com/Gitlawb/zero/internal/zeroruntime"
-)
-
-// rootFlagOrderings is every ordering of the given flag groups, each group
-// kept intact so a flag stays next to its value.
-func rootFlagOrderings(groups [][]string) [][]string {
-	if len(groups) == 0 {
-		return [][]string{{}}
-	}
-	var orderings [][]string
-	for index, group := range groups {
-		rest := append(append([][]string{}, groups[:index]...), groups[index+1:]...)
-		for _, tail := range rootFlagOrderings(rest) {
-			orderings = append(orderings, append(append([]string{}, group...), tail...))
-		}
-	}
-	return orderings
-}
-
-// ROOT FLAGS COMPOSE IN ANY ORDER. Each leading-flag splitter stops at the first
-// token it does not own, so running them once in a fixed sequence made the
-// order the operator wrote them in load-bearing: `zero --allow-escalation
-// --theme auto` stranded `--theme auto` as an unknown command and exited with
-// an argument error instead of launching. Every ordering of the three root
-// flags, with --skip-permissions-unsafe absent or at any position, has to reach
-// the TUI with all three applied.
-func TestRootFlagsComposeInAnyOrder(t *testing.T) {
-	extra := t.TempDir()
-	resolvedExtra, err := filepath.EvalSymlinks(extra)
-	if err != nil {
-		t.Fatal(err)
-	}
-	groups := [][]string{{"--add-dir", extra}, {"--theme", "auto"}, {"--allow-escalation"}}
-	cases := rootFlagOrderings(groups)
-	cases = append(cases, rootFlagOrderings(append(groups, []string{"--skip-permissions-unsafe"}))...)
-	if len(cases) != 6+24 {
-		t.Fatalf("SETUP INVALID: %d orderings, want 30", len(cases))
-	}
-	for _, args := range cases {
-		t.Run(strings.Join(args, " "), func(t *testing.T) {
-			options := captureTUIOptions(t, args...)
-			wantMode := agent.PermissionModeAsk
-			for _, arg := range args {
-				if arg == "--skip-permissions-unsafe" {
-					wantMode = agent.PermissionModeUnsafe
-				}
-			}
-			if options.PermissionMode != wantMode {
-				t.Errorf("PermissionMode = %q, want %q", options.PermissionMode, wantMode)
-			}
-			if !options.AllowEscalation {
-				t.Error("escalation not enabled")
-			}
-			if options.Theme != "auto" {
-				t.Errorf("Theme = %q, want auto", options.Theme)
-			}
-			if options.AgentOptions.Sandbox == nil {
-				t.Fatal("no sandbox engine on the launched options")
-			}
-			roots := options.AgentOptions.Sandbox.Scope().Roots()
-			found := false
-			for _, root := range roots {
-				if root == resolvedExtra {
-					found = true
-				}
-			}
-			if !found {
-				t.Errorf("scope roots = %v, want the --add-dir root %q", roots, resolvedExtra)
-			}
-		})
-	}
-}
-
-// The last --theme wins even with another root flag between two of them, and a
-// --theme written before --skip-permissions-unsafe reaches the TUI: the unsafe
-// path used to launch with only the theme written after the flag, dropping one
-// written before it.
-func TestRootThemeLastOccurrenceWinsAcrossOtherFlags(t *testing.T) {
-	for _, testCase := range []struct {
-		args []string
-		want string
-	}{
-		{[]string{"--theme", "light", "--allow-escalation", "--theme", "auto"}, "auto"},
-		{[]string{"--theme", "auto", "--skip-permissions-unsafe"}, "auto"},
-		{[]string{"--theme", "light", "--skip-permissions-unsafe", "--theme", "auto"}, "auto"},
-	} {
-		t.Run(strings.Join(testCase.args, " "), func(t *testing.T) {
-			options := captureTUIOptions(t, testCase.args...)
-			if options.Theme != testCase.want {
-				t.Fatalf("Theme = %q, want %q", options.Theme, testCase.want)
-			}
-		})
-	}
-}
-
-// THE ROOT FLAG REACHES EXEC. A --allow-escalation written before the
-// subcommand is forwarded the way --add-dir is, so `zero --allow-escalation -p
-// "..."` runs with the opt-in the help text promises instead of silently
-// without it. The negative control is the same run without the flag, which
-// must not advertise escalate_model.
-func TestRootAllowEscalationForwardsIntoExec(t *testing.T) {
-	for _, testCase := range []struct {
-		name string
-		args []string
-	}{
-		{"exec subcommand", []string{"--allow-escalation", "exec", "say hi"}},
-		{"prompt flag", []string{"--allow-escalation", "-p", "say hi"}},
-	} {
-		t.Run(testCase.name, func(t *testing.T) {
-			if !execAdvertisesEscalateModel(t, testCase.args) {
-				t.Fatalf("%v ran without escalate_model advertised: the root flag was dropped before exec", testCase.args)
-			}
-			if execAdvertisesEscalateModel(t, testCase.args[1:]) {
-				t.Fatalf("%v advertised escalate_model without the flag", testCase.args[1:])
-			}
-		})
-	}
-}
-
-// Everywhere else the flag is rejected loudly rather than discarded, the way
-// --add-dir is: help and version run no agent and could only ignore it.
-func TestRootAllowEscalationIsRejectedWhereNothingConsumesIt(t *testing.T) {
-	for _, args := range [][]string{
-		{"--allow-escalation", "version"},
-		{"--allow-escalation", "help"},
-		{"--allow-escalation", "completions", "bash"},
-	} {
-		t.Run(strings.Join(args, " "), func(t *testing.T) {
-			var stdout, stderr bytes.Buffer
-			launched := false
-			exitCode := runWithDeps(args, &stdout, &stderr, appDeps{
-				getwd:  func() (string, error) { return t.TempDir(), nil },
-				runTUI: func(context.Context, tui.Options) int { launched = true; return exitSuccess },
-			})
-			if exitCode == exitSuccess || launched {
-				t.Fatalf("exit = %d launched = %v: the flag was discarded instead of rejected", exitCode, launched)
-			}
-			if !strings.Contains(stderr.String(), "--allow-escalation is only supported for the interactive TUI and exec") {
-				t.Fatalf("stderr does not name the flag: %s", stderr.String())
-			}
-		})
-	}
-}
-
-// execAdvertisesEscalateModel dispatches args through the root command with a
-// provider that records the tools advertised on the first request, and reports
-// whether escalate_model was among them.
-func execAdvertisesEscalateModel(t *testing.T, args []string) bool {
-	t.Helper()
-	isolateCLIUserState(t)
-	provider := &toolListingProvider{}
-	var stdout, stderr bytes.Buffer
-	exitCode := runWithDeps(args, &stdout, &stderr, appDeps{
-		getwd: func() (string, error) { return t.TempDir(), nil },
-		resolveConfig: func(string, config.Overrides) (config.ResolvedConfig, error) {
-			return execResolvedConfig(), nil
-		},
-		newProvider: func(config.ProviderProfile) (zeroruntime.Provider, error) {
-			return provider, nil
-		},
-		newSandboxStore: func() (*sandbox.GrantStore, error) {
-			return sandbox.NewGrantStore(sandbox.StoreOptions{FilePath: filepath.Join(t.TempDir(), "sandbox-grants.json")})
-		},
-	})
-	if exitCode != exitSuccess {
-		t.Fatalf("%v: exit = %d, stderr = %s", args, exitCode, stderr.String())
-	}
-	if provider.requests == 0 {
-		t.Fatalf("SETUP INVALID: %v never reached the provider", args)
-	}
-	for _, name := range provider.toolNames {
-		if name == "escalate_model" {
-			return true
-		}
-	}
-	return false
-}
-
-// toolListingProvider answers every request with a one-line text reply and
-// keeps the tool names advertised on the first one.
-type toolListingProvider struct {
-	requests  int
-	toolNames []string
-}
-
-func (provider *toolListingProvider) StreamCompletion(_ context.Context, request zeroruntime.CompletionRequest) (<-chan zeroruntime.StreamEvent, error) {
-	provider.requests++
-	if provider.requests == 1 {
-		for _, tool := range request.Tools {
-			provider.toolNames = append(provider.toolNames, tool.Name)
-		}
-	}
-	ch := make(chan zeroruntime.StreamEvent, 2)
-	ch <- zeroruntime.StreamEvent{Type: zeroruntime.StreamEventText, Content: "hi"}
-	ch <- zeroruntime.StreamEvent{Type: zeroruntime.StreamEventDone}
-	close(ch)
-	return ch, nil
-}

internal/cli/setup.go

@@ -42,7 +42,7 @@ func runSetup(args []string, stdout io.Writer, stderr io.Writer, deps appDeps) i
 		return exitSuccess
 	}
 	if strings.TrimSpace(options.catalogID) == "" {
-		return runInteractiveTUIWithSetup(stderr, deps, "", nil, "", true, false)
+		return runInteractiveTUIWithSetup(stderr, deps, "", nil, "", true)
 	}
 
 	result, err := saveSetupProvider(deps, tui.SetupSelection{

internal/cli/tui_escalation_test.go

@@ -1,126 +0,0 @@
-package cli
-
-import (
-	"bytes"
-	"context"
-	"strings"
-	"testing"
-
-	"github.com/Gitlawb/zero/internal/tui"
-)
-
-// captureTUIOptions runs the root command with the TUI launch intercepted, and
-// returns the options the interactive session would have started with.
-func captureTUIOptions(t *testing.T, args ...string) tui.Options {
-	t.Helper()
-	isolateCLIUserState(t)
-	var captured tui.Options
-	var stdout, stderr bytes.Buffer
-	workspace := t.TempDir()
-	exitCode := runWithDeps(args, &stdout, &stderr, appDeps{
-		getwd: func() (string, error) { return workspace, nil },
-		runTUI: func(_ context.Context, options tui.Options) int {
-			captured = options
-			return exitSuccess
-		},
-	})
-	if exitCode != exitSuccess {
-		t.Fatalf("exitCode = %d stdout=%s stderr=%s", exitCode, stdout.String(), stderr.String())
-	}
-	return captured
-}
-
-func hasEscalateModel(options tui.Options) bool {
-	if options.AgentOptions.Registry == nil {
-		return false
-	}
-	_, registered := options.AgentOptions.Registry.Get("escalate_model")
-	return registered
-}
-
-// ESCALATION IS OFF UNLESS THE OPERATOR ASKS FOR IT.
-//
-// Escalation moves a run onto a different model, changing what it costs and which
-// provider sees the conversation, so the interactive surface answers this the same
-// conservative way `zero exec --allow-escalation` already does.
-func TestInteractiveTUIRegistersEscalateModelOnlyWithTheFlag(t *testing.T) {
-	if hasEscalateModel(captureTUIOptions(t)) {
-		t.Error("escalate_model was registered without --allow-escalation")
-	}
-	if !hasEscalateModel(captureTUIOptions(t, "--allow-escalation")) {
-		t.Error("--allow-escalation did not register escalate_model")
-	}
-}
-
-// THE TOOL AND THE SWITCHERS ARE ONE FEATURE, NOT TWO.
-//
-// This is the failure the whole change exists to avoid. The agent loop performs a
-// switch only when a switcher is wired, so registering escalate_model without
-// wiring one ships a tool the model can call and the loop will silently ignore:
-// the run reports an escalation that never happened. The reverse is merely dead
-// code. Both halves ride on the same flag and this asserts they cannot be
-// separated, whichever half a future change touches.
-func TestInteractiveTUIEscalationToolAndSwitchersAreWiredTogether(t *testing.T) {
-	for _, testCase := range []struct {
-		name string
-		args []string
-		want bool
-	}{
-		{name: "default", args: nil, want: false},
-		{name: "flagged", args: []string{"--allow-escalation"}, want: true},
-	} {
-		t.Run(testCase.name, func(t *testing.T) {
-			options := captureTUIOptions(t, testCase.args...)
-			if got := hasEscalateModel(options); got != testCase.want {
-				t.Fatalf("escalate_model registered = %v, want %v", got, testCase.want)
-			}
-			if options.AllowEscalation != testCase.want {
-				t.Errorf("AllowEscalation = %v, want %v: the tool is registered on one gate and the switchers on another, so they can drift apart",
-					options.AllowEscalation, testCase.want)
-			}
-		})
-	}
-}
-
-// The flag is accepted on either side of --skip-permissions-unsafe, like the
-// other root flags that may appear there.
-func TestInteractiveTUIAcceptsAllowEscalationAroundUnsafe(t *testing.T) {
-	for _, args := range [][]string{
-		{"--allow-escalation", "--skip-permissions-unsafe"},
-		{"--skip-permissions-unsafe", "--allow-escalation"},
-	} {
-		options := captureTUIOptions(t, args...)
-		if !options.AllowEscalation {
-			t.Errorf("%v did not enable escalation", args)
-		}
-		if !hasEscalateModel(options) {
-			t.Errorf("%v did not register escalate_model", args)
-		}
-	}
-}
-
-// An =value form is a loud error rather than a silent enable, so a mistyped
-// --allow-escalation=false cannot turn the feature ON.
-func TestAllowEscalationRejectsAValue(t *testing.T) {
-	var stdout, stderr bytes.Buffer
-	exitCode := runWithDeps([]string{"--allow-escalation=false"}, &stdout, &stderr, appDeps{
-		getwd:  func() (string, error) { return t.TempDir(), nil },
-		runTUI: func(context.Context, tui.Options) int { return exitSuccess },
-	})
-	if exitCode == exitSuccess {
-		t.Fatal("--allow-escalation=false was accepted; a mistyped disable must not silently enable escalation")
-	}
-	if !strings.Contains(stderr.String(), "--allow-escalation takes no value") {
-		t.Errorf("stderr does not explain the flag: %s", stderr.String())
-	}
-}
-
-func TestRootHelpDocumentsAllowEscalation(t *testing.T) {
-	var stdout, stderr bytes.Buffer
-	if exitCode := runWithDeps([]string{"--help"}, &stdout, &stderr, appDeps{}); exitCode != exitSuccess {
-		t.Fatalf("exitCode = %d stderr=%s", exitCode, stderr.String())
-	}
-	if !strings.Contains(stdout.String(), "--allow-escalation") {
-		t.Error("the root help does not mention --allow-escalation, so the flag is undiscoverable")
-	}
-}

internal/cli/user_state_isolation_test.go

@@ -1,139 +0,0 @@
-package cli
-
-import (
-	"os"
-	"path/filepath"
-	"strings"
-	"testing"
-
-	"github.com/Gitlawb/zero/internal/config"
-)
-
-// userStateEnvNames is every per-user base directory the root command can
-// resolve against, across platforms. One throwaway root behind all of them
-// lands the resolution inside it whichever branch it takes.
-var userStateEnvNames = []string{
-	"HOME", "USERPROFILE", "APPDATA", "LOCALAPPDATA",
-	"XDG_CONFIG_HOME", "XDG_DATA_HOME", "XDG_CACHE_HOME", "XDG_STATE_HOME",
-}
-
-// isolateCLIUserState points every user-scoped path the root command touches at
-// throwaway directories, and keeps credential work off the host keyring.
-//
-// A TEMPORARY WORKING DIRECTORY IS NOT ISOLATION. runWithDeps fills the
-// dependencies a test leaves out with the production ones, and the launch paths
-// read user config, open stores, refresh the models.dev cache and, for an
-// interactive run, migrate any inline plaintext API key into the credential
-// store before they ever reach an injected callback. Without this, running these
-// tests on a developer machine rewrites that developer's config.json and moves
-// their key into their keychain, makes a real network call, and reports results
-// that depend on whatever providers, MCP servers and plugins that machine has.
-func isolateCLIUserState(t *testing.T) {
-	t.Helper()
-	root := t.TempDir()
-	for _, name := range userStateEnvNames {
-		t.Setenv(name, root)
-	}
-	// The models.dev overlay cache, and the background refresh that writes it:
-	// a wiring test has no business making a network call or leaving a cache
-	// file behind.
-	t.Setenv("ZERO_MODELS_CACHE_PATH", filepath.Join(root, "modelsdev.json"))
-	t.Setenv("ZERO_DISABLE_MODELS_FETCH", "1")
-	// Credentials resolve keyring-first. This keeps a migrated key in a file
-	// under the fixture root rather than in the developer's OS keychain.
-	t.Setenv("ZERO_CRED_STORAGE", "encrypted-file")
-}
-
-// AND THE ISOLATION IS ITSELF PINNED, ONE HELPER AT A TIME. A seeded config
-// outside the helper fixture roots stands in for a developer's real one: the
-// launch helper must leave it exactly as it found it, inline API key included,
-// must not write a credential file beside it, and must have moved the per-user
-// paths off that root before running anything.
-//
-// EACH HELPER GETS ITS OWN SUBTEST because t.Setenv restores at the end of the
-// test, not when the helper returns: exercising both in one test would let the
-// first helper isolation cover for a second helper that had none.
-func TestCLILaunchHelpersLeaveUserStateAlone(t *testing.T) {
-	for _, testCase := range []struct {
-		name     string
-		exercise func(*testing.T)
-	}{
-		{"captureTUIOptions", func(t *testing.T) { _ = captureTUIOptions(t, "--allow-escalation") }},
-		{"execAdvertisesEscalateModel", func(t *testing.T) {
-			_ = execAdvertisesEscalateModel(t, []string{"--allow-escalation", "exec", "say hi"})
-		}},
-	} {
-		t.Run(testCase.name, func(t *testing.T) {
-			seedRoot, configPath, seeded, before := seedEmulatedUserConfig(t)
-
-			testCase.exercise(t)
-
-			after, err := os.ReadFile(configPath)
-			if err != nil {
-				t.Fatal(err)
-			}
-			if string(after) != string(seeded) {
-				t.Errorf("the seeded user config was rewritten:\n before: %s\n  after: %s", seeded, after)
-			}
-			entries, err := os.ReadDir(filepath.Dir(configPath))
-			if err != nil {
-				t.Fatal(err)
-			}
-			if len(entries) != len(before) {
-				names := []string{}
-				for _, entry := range entries {
-					names = append(names, entry.Name())
-				}
-				t.Errorf("the user config directory gained entries: %v", names)
-			}
-
-			// The checks above catch what this platform happens to write. This
-			// one catches the missing isolation itself, so a startup path that
-			// writes somewhere else, or only sometimes, is covered too.
-			resolved, err := config.DefaultUserConfigPath()
-			if err != nil {
-				t.Fatal(err)
-			}
-			if strings.HasPrefix(resolved, seedRoot) {
-				t.Errorf("user config still resolves inside the seeded root (%s): the helper installed no isolation", resolved)
-			}
-			if os.Getenv("ZERO_DISABLE_MODELS_FETCH") == "" {
-				t.Error("the helper left the background models.dev refresh enabled, so this test can make a network call and write a cache file")
-			}
-			if os.Getenv("ZERO_CRED_STORAGE") == "" {
-				t.Error("the helper left credential storage resolving keyring-first, so a migrated key can reach the host keychain")
-			}
-		})
-	}
-}
-
-// seedEmulatedUserConfig points the per-user base directories at a throwaway
-// root and writes a config carrying an inline plaintext API key there, which is
-// what the startup migration rewrites. It returns that root, the config path,
-// its bytes, and the directory listing to compare against.
-func seedEmulatedUserConfig(t *testing.T) (string, string, []byte, []os.DirEntry) {
-	t.Helper()
-	seedRoot := t.TempDir()
-	for _, name := range userStateEnvNames {
-		t.Setenv(name, seedRoot)
-	}
-	configPath, err := config.DefaultUserConfigPath()
-	if err != nil {
-		t.Fatal(err)
-	}
-	if !strings.HasPrefix(configPath, seedRoot) {
-		t.Fatalf("SETUP INVALID: user config resolved to %q, outside the seeded root %q", configPath, seedRoot)
-	}
-	if err := os.MkdirAll(filepath.Dir(configPath), 0o755); err != nil {
-		t.Fatal(err)
-	}
-	seeded := []byte(`{"providers":[{"name":"anthropic","providerKind":"anthropic","model":"claude-haiku-4.5","apiKey":"sk-seeded-plaintext-key"}]}`)
-	if err := os.WriteFile(configPath, seeded, 0o600); err != nil {
-		t.Fatal(err)
-	}
-	before, err := os.ReadDir(filepath.Dir(configPath))
-	if err != nil {
-		t.Fatal(err)
-	}
-	return seedRoot, configPath, seeded, before
-}

internal/providerhealth/providerhealth.go

@@ -19,6 +19,7 @@ import (
 	"github.com/Gitlawb/zero/internal/providercatalog"
 	"github.com/Gitlawb/zero/internal/providers"
 	"github.com/Gitlawb/zero/internal/providers/providerio"
+	"github.com/Gitlawb/zero/internal/proxydial"
 	"github.com/Gitlawb/zero/internal/redaction"
 )
 
@@ -518,9 +519,15 @@ func newConnectivityClient(timeout time.Duration, resolver Resolver, sensitiveHe
 		transport = &http.Transport{}
 	}
 	transport.DialContext = safeDialContext(resolver, allowLoopbackOrPrivate)
+	// WRAPPED, SO THE DIALER LEARNS THE ROUTE THIS TRANSPORT CHOSE. The wrapper
+	// records the proxy selected for each request on that request, and the
+	// dialer reads it back on the dial that request causes; installing the bare
+	// transport instead would leave a proxied dial looking like a loopback
+	// target and fail the probe (#569). The cloned default transport already
+	// reads HTTPS_PROXY and friends; nothing new is enabled.
 	return &http.Client{
 		Timeout:   timeout,
-		Transport: transport,
+		Transport: proxydial.Wrap(transport),
 		CheckRedirect: func(req *http.Request, via []*http.Request) error {
 			if len(via) >= maxConnectivityRedirects {
 				return fmt.Errorf("provider connectivity exceeded %d redirects", maxConnectivityRedirects)
@@ -583,6 +590,17 @@ func sensitiveAuthHeaderNames(profile config.ProviderProfile, kind config.Provid
 func safeDialContext(resolver Resolver, allowLoopbackOrPrivate bool) func(context.Context, string, string) (net.Conn, error) {
 	dialer := &net.Dialer{Timeout: 10 * time.Second, KeepAlive: 30 * time.Second}
 	return func(ctx context.Context, network, address string) (net.Conn, error) {
+		// THE PROXY IS NOT THE TARGET. With HTTPS_PROXY set to a local forward
+		// proxy, the transport dials the proxy first and tunnels the request
+		// through it, and this dialer used to refuse that dial as a loopback
+		// address: "proxyconnect tcp: ... loopback hosts are blocked" for a
+		// request whose real target had already been validated (#569). The
+		// target validation is unchanged; only the dial the transport opens to
+		// the proxy it picked for this very request is let past the guard, and a
+		// direct dial is checked as it always was.
+		if proxydial.IsProxyDial(ctx) {
+			return dialer.DialContext(ctx, network, address)
+		}
 		host, port, err := net.SplitHostPort(address)
 		if err != nil {
 			return nil, err

internal/providerhealth/proxy_dial_test.go

@@ -0,0 +1,218 @@
+package providerhealth
+
+import (
+	"context"
+	"errors"
+	"net"
+	"net/http"
+	"net/netip"
+	"net/url"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/Gitlawb/zero/internal/proxydial"
+)
+
+// connectivityClientWithProxy builds the real connectivity client and swaps in
+// a proxy function, which is how the transport learns its route. The
+// environment is left alone deliberately: http.ProxyFromEnvironment reads it
+// once per process, so an environment-driven test would depend on test order.
+func connectivityClientWithProxy(t *testing.T, resolver Resolver, proxyFor func(*http.Request) (*url.URL, error)) *http.Client {
+	t.Helper()
+	client := newConnectivityClient(3*time.Second, resolver, nil, false)
+	wrapped, ok := client.Transport.(*proxydial.Transport)
+	if !ok {
+		t.Fatalf("transport = %T, want the route-recording wrapper; without it no dial can be recognised as the proxy dial", client.Transport)
+	}
+	wrapped.Proxy = proxyFor
+	return client
+}
+
+// recordingProxy is a listener standing in for a local forward proxy. It
+// records the first line it receives and hangs up.
+func recordingProxy(t *testing.T) (*url.URL, <-chan string) {
+	t.Helper()
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { _ = listener.Close() })
+	arrived := make(chan string, 1)
+	go func() {
+		conn, err := listener.Accept()
+		if err != nil {
+			return
+		}
+		defer conn.Close()
+		buffer := make([]byte, 256)
+		n, _ := conn.Read(buffer)
+		arrived <- string(buffer[:n])
+	}()
+	proxyURL, err := url.Parse("http://" + listener.Addr().String())
+	if err != nil {
+		t.Fatal(err)
+	}
+	return proxyURL, arrived
+}
+
+// THE PROXY IS NOT THE TARGET, AND THE GUARD HAS TO KNOW THE DIFFERENCE.
+//
+// With HTTPS_PROXY set to a local forward proxy, the transport dials the proxy
+// first and tunnels the request through it. This dialer refused that dial as a
+// loopback address, so `zero doctor --connectivity` failed with "proxyconnect
+// tcp: ... loopback hosts are blocked" for a target that had already been
+// validated and was public (#569). Driven through the real client, so the route
+// is the transport's own decision.
+func TestConnectivityClientTunnelsThroughTheConfiguredProxy(t *testing.T) {
+	proxyURL, arrived := recordingProxy(t)
+	client := connectivityClientWithProxy(t,
+		staticResolver{err: errors.New("resolver must not be called for a proxied request")},
+		func(*http.Request) (*url.URL, error) { return proxyURL, nil })
+
+	request, err := http.NewRequestWithContext(context.Background(), http.MethodGet, "https://api.example.com/v1/models", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = client.Do(request)
+	select {
+	case first := <-arrived:
+		if line := strings.SplitN(first, "\r\n", 2)[0]; line != "CONNECT api.example.com:443 HTTP/1.1" {
+			t.Fatalf("proxy received %q, want a CONNECT for the validated target", line)
+		}
+	case <-time.After(5 * time.Second):
+		t.Fatalf("the proxy never received a connection; request error: %v", err)
+	}
+}
+
+// AND A DIRECT REQUEST STAYS GUARDED, EVEN WHEN ITS ORIGIN IS THE PROXY'S OWN
+// ADDRESS.
+//
+// This is the NO_PROXY shape: the proxy function sends one host direct. An
+// exemption derived from asking that function about a request of our own
+// invention would answer "proxied" for the excluded host too, and this dial,
+// whose address equals the configured proxy endpoint, would skip the resolver
+// and reach whatever the name resolves to at connect time.
+func TestDirectRequestToTheProxyEndpointIsStillGuarded(t *testing.T) {
+	proxyURL, err := url.Parse("http://rebind.example:80")
+	if err != nil {
+		t.Fatal(err)
+	}
+	lookups := 0
+	resolver := countingResolver{
+		onLookup: func() { lookups++ },
+		addr:     netip.MustParseAddr("10.0.0.5"),
+	}
+	client := connectivityClientWithProxy(t, resolver, func(request *http.Request) (*url.URL, error) {
+		if request.URL.Hostname() == "rebind.example" {
+			return nil, nil
+		}
+		return proxyURL, nil
+	})
+
+	request, err := http.NewRequestWithContext(context.Background(), http.MethodGet, "http://rebind.example/data", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = client.Do(request)
+
+	if lookups == 0 {
+		t.Fatal("the direct dial skipped the safety resolver because its address matched the configured proxy endpoint")
+	}
+	var safety endpointSafetyError
+	if !errors.As(err, &safety) {
+		t.Fatalf("err = %v, want the private answer to be refused", err)
+	}
+}
+
+// A proxy configured with a Unicode hostname is dialed by its IDNA-encoded
+// name, and it is still the proxy: the request must reach it rather than be
+// refused as an ordinary private address.
+func TestUnicodeProxyHostnameIsStillTheProxy(t *testing.T) {
+	dialed := ""
+	client := connectivityClientWithProxy(t,
+		staticResolver{err: errors.New("resolver must not be called for a proxied request")},
+		func(*http.Request) (*url.URL, error) { return url.Parse("http://büro.example:3067") })
+	wrapped := client.Transport.(*proxydial.Transport)
+	guarded := wrapped.DialContext
+	wrapped.DialContext = func(ctx context.Context, network, address string) (net.Conn, error) {
+		dialed = address
+		return guarded(ctx, network, address)
+	}
+
+	request, err := http.NewRequestWithContext(context.Background(), http.MethodGet, "https://api.example.com/v1/models", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = client.Do(request)
+
+	if dialed != "xn--bro-hoa.example:3067" {
+		t.Fatalf("SETUP INVALID: dialed %q, want the IDNA-encoded proxy endpoint", dialed)
+	}
+	var safety endpointSafetyError
+	if errors.As(err, &safety) {
+		t.Fatalf("the configured proxy was refused by the guard: %v", err)
+	}
+}
+
+// Without a proxy the guard is exactly what it was: loopback is refused.
+func TestSafeDialContextStillRefusesLoopbackWithoutAProxy(t *testing.T) {
+	dial := safeDialContext(staticResolver{err: errors.New("resolver must not be called")}, false)
+	conn, err := dial(context.Background(), "tcp", "127.0.0.1:3067")
+	if conn != nil {
+		_ = conn.Close()
+		t.Fatal("loopback was dialed with no proxy configured")
+	}
+	var safety endpointSafetyError
+	if !errors.As(err, &safety) {
+		t.Fatalf("err = %v, want endpointSafetyError", err)
+	}
+}
+
+// A sibling loopback port is not the proxy, and the guard is unchanged for it.
+func TestSafeDialContextRefusesALoopbackPortThatIsNotTheProxy(t *testing.T) {
+	proxyURL, arrived := recordingProxy(t)
+	client := connectivityClientWithProxy(t,
+		staticResolver{err: errors.New("resolver must not be called")},
+		func(request *http.Request) (*url.URL, error) {
+			// Only the https probe is proxied; the http one below is direct and
+			// happens to point at the neighbouring port.
+			if request.URL.Scheme == "https" {
+				return proxyURL, nil
+			}
+			return nil, nil
+		})
+
+	_, port, _ := net.SplitHostPort(proxyURL.Host)
+	number, _ := strconv.Atoi(port)
+	sibling := "http://" + net.JoinHostPort("127.0.0.1", strconv.Itoa(number+1)) + "/"
+	request, err := http.NewRequestWithContext(context.Background(), http.MethodGet, sibling, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = client.Do(request)
+	var safety endpointSafetyError
+	if !errors.As(err, &safety) {
+		t.Fatalf("err = %v, want a loopback port beside the proxy to stay blocked", err)
+	}
+	select {
+	case first := <-arrived:
+		t.Fatalf("the proxy received a connection it should not have: %q", first)
+	default:
+	}
+}
+
+// countingResolver answers with one address and reports each lookup, so a test
+// can tell a skipped guard from a guard that ran and allowed the address.
+type countingResolver struct {
+	onLookup func()
+	addr     netip.Addr
+}
+
+func (resolver countingResolver) LookupNetIP(context.Context, string, string) ([]netip.Addr, error) {
+	if resolver.onLookup != nil {
+		resolver.onLookup()
+	}
+	return []netip.Addr{resolver.addr}, nil
+}

internal/providers/escalation.go

@@ -1,89 +0,0 @@
-package providers
-
-import (
-	"context"
-
-	"github.com/Gitlawb/zero/internal/config"
-	"github.com/Gitlawb/zero/internal/zeroruntime"
-)
-
-// EscalationSwitchers builds the two mid-run model switchers a run installs when
-// it has opted into escalation.
-//
-// ONE IMPLEMENTATION, TWO SURFACES. exec grew this first, and the interactive TUI
-// needs the same behaviour rather than a similar one. The part that is easy to get
-// subtly wrong is not the switch, it is the nil handling around it, and a second
-// copy of that would only ever be exercised on one surface.
-//
-// THE NIL CONTRACTS ARE THE CONTRACT. The agent loop reassigns the provider only
-// when a switcher returns a non-nil one, so a (nil, nil) return means "no swap"
-// and has to leave everything as it was, including whatever the caller tracks
-// through onSwitch. onSwitch therefore fires only on a real swap, and may be nil.
-// An error is reported to the loop, which records a note and continues on the
-// current model.
-//
-// The session switcher comes back nil unless the run STARTED optimized. A run
-// that began on the default adapter stays on it, so escalation cannot quietly
-// change the transport underneath a session.
-func EscalationSwitchers(
-	profile config.ProviderProfile,
-	provider zeroruntime.Provider,
-	newProvider func(config.ProviderProfile) (zeroruntime.Provider, error),
-	onSwitch func(modelID string),
-) (
-	func(context.Context, string) (zeroruntime.Provider, error),
-	func(context.Context, string) (zeroruntime.TurnSessionProvider, error),
-) {
-	if newProvider == nil {
-		return nil, nil
-	}
-	// The escalated profile is the run's profile with the model replaced, so the
-	// credential, base URL and headers travel with it. Callers pass a newProvider
-	// that already applies the stored key, which is why there is no per-site key
-	// handling here.
-	switchTo := func(modelID string) (config.ProviderProfile, zeroruntime.Provider, error) {
-		switched := profile
-		switched.Model = modelID
-		provider, err := newProvider(switched)
-		return switched, provider, err
-	}
-
-	modelSwitcher := func(_ context.Context, modelID string) (zeroruntime.Provider, error) {
-		_, switchedProvider, err := switchTo(modelID)
-		if err != nil {
-			return nil, err
-		}
-		if switchedProvider == nil {
-			return nil, nil
-		}
-		if onSwitch != nil {
-			onSwitch(modelID)
-		}
-		return switchedProvider, nil
-	}
-
-	turnSessions, _ := OptimizedTurnSessions(profile, provider, Options{})
-	if turnSessions == nil {
-		return modelSwitcher, nil
-	}
-
-	sessionSwitcher := func(_ context.Context, modelID string) (zeroruntime.TurnSessionProvider, error) {
-		switchedProfile, switchedProvider, err := switchTo(modelID)
-		if err != nil {
-			return nil, err
-		}
-		if switchedProvider == nil {
-			return nil, nil
-		}
-		if onSwitch != nil {
-			onSwitch(modelID)
-		}
-		if optimized, ok := OptimizedTurnSessions(switchedProfile, switchedProvider, Options{}); ok {
-			return optimized, nil
-		}
-		// Ineligible target: the default adapter, but carrying the switched
-		// model's own capability projection rather than the original's.
-		return DefaultTurnSessions(switchedProfile, switchedProvider, Options{}), nil
-	}
-	return modelSwitcher, sessionSwitcher
-}

internal/providers/escalation_test.go

@@ -1,130 +0,0 @@
-package providers
-
-import (
-	"context"
-	"errors"
-	"testing"
-
-	"github.com/Gitlawb/zero/internal/config"
-	"github.com/Gitlawb/zero/internal/zeroruntime"
-)
-
-type escalationStubProvider struct{ model string }
-
-func (escalationStubProvider) Name() string { return "stub" }
-
-func (escalationStubProvider) StreamCompletion(context.Context, zeroruntime.CompletionRequest) (<-chan zeroruntime.StreamEvent, error) {
-	ch := make(chan zeroruntime.StreamEvent)
-	close(ch)
-	return ch, nil
-}
-
-// THE ESCALATED PROFILE IS THE RUN'S PROFILE WITH THE MODEL REPLACED.
-//
-// Everything else has to travel: the base URL, the credential and the headers.
-// Building a bare profile with only the model set would escalate onto an
-// unauthenticated endpoint, and the failure would look like a provider outage.
-func TestEscalationSwitchersKeepTheProfileAndReplaceOnlyTheModel(t *testing.T) {
-	profile := config.ProviderProfile{Name: "acme", Model: "small", BaseURL: "https://acme.test", APIKey: "sk-live"}
-	var asked config.ProviderProfile
-	switcher, _ := EscalationSwitchers(profile, escalationStubProvider{}, func(p config.ProviderProfile) (zeroruntime.Provider, error) {
-		asked = p
-		return escalationStubProvider{model: p.Model}, nil
-	}, nil)
-	if switcher == nil {
-		t.Fatal("no model switcher was built for a run that opted into escalation")
-	}
-	if _, err := switcher(context.Background(), "large"); err != nil {
-		t.Fatalf("switch: %v", err)
-	}
-	if asked.Model != "large" {
-		t.Errorf("escalated to model %q, want large", asked.Model)
-	}
-	if asked.BaseURL != profile.BaseURL || asked.APIKey != profile.APIKey || asked.Name != profile.Name {
-		t.Errorf("the escalated profile lost the run's provider identity: %+v", asked)
-	}
-}
-
-// A (nil, nil) RETURN MEANS NO SWAP, AND MUST CHANGE NOTHING.
-//
-// The agent loop reassigns the provider only when it gets a non-nil one, so a nil
-// provider leaves the run on its current model. Anything the caller tracks
-// through onSwitch has to stay in step with that, or usage gets attributed to a
-// model the run never moved to.
-func TestEscalationSwitchersDoNotReportASwitchThatDidNotHappen(t *testing.T) {
-	switched := []string{}
-	switcher, _ := EscalationSwitchers(
-		config.ProviderProfile{Model: "small"}, escalationStubProvider{},
-		func(config.ProviderProfile) (zeroruntime.Provider, error) { return nil, nil },
-		func(modelID string) { switched = append(switched, modelID) },
-	)
-	provider, err := switcher(context.Background(), "large")
-	if err != nil {
-		t.Fatalf("a nil provider is not an error: %v", err)
-	}
-	if provider != nil {
-		t.Errorf("provider = %v, want nil", provider)
-	}
-	if len(switched) != 0 {
-		t.Errorf("onSwitch fired for a swap that never happened: %v", switched)
-	}
-}
-
-// An error reaches the loop, which records it and stays on the current model.
-func TestEscalationSwitchersReportProviderErrors(t *testing.T) {
-	want := errors.New("no credential for that model")
-	switched := []string{}
-	switcher, _ := EscalationSwitchers(
-		config.ProviderProfile{Model: "small"}, escalationStubProvider{},
-		func(config.ProviderProfile) (zeroruntime.Provider, error) { return nil, want },
-		func(modelID string) { switched = append(switched, modelID) },
-	)
-	if _, err := switcher(context.Background(), "large"); !errors.Is(err, want) {
-		t.Errorf("err = %v, want %v", err, want)
-	}
-	if len(switched) != 0 {
-		t.Errorf("onSwitch fired for a failed switch: %v", switched)
-	}
-}
-
-// And a real swap does report itself, or the caller's attribution never moves.
-func TestEscalationSwitchersReportARealSwitch(t *testing.T) {
-	switched := []string{}
-	switcher, _ := EscalationSwitchers(
-		config.ProviderProfile{Model: "small"}, escalationStubProvider{},
-		func(p config.ProviderProfile) (zeroruntime.Provider, error) {
-			return escalationStubProvider{model: p.Model}, nil
-		},
-		func(modelID string) { switched = append(switched, modelID) },
-	)
-	if _, err := switcher(context.Background(), "large"); err != nil {
-		t.Fatalf("switch: %v", err)
-	}
-	if len(switched) != 1 || switched[0] != "large" {
-		t.Errorf("onSwitch recorded %v, want one switch to large", switched)
-	}
-}
-
-// A RUN THAT STARTED ON THE DEFAULT ADAPTER STAYS ON IT.
-//
-// The session switcher is installed only when the run START is optimized, so
-// escalation cannot quietly change the transport underneath a session that never
-// had one.
-func TestEscalationSwitchersOmitTheSessionSwitcherForAnUnoptimizedStart(t *testing.T) {
-	_, sessionSwitcher := EscalationSwitchers(
-		config.ProviderProfile{Name: "acme", Model: "small"}, escalationStubProvider{},
-		func(p config.ProviderProfile) (zeroruntime.Provider, error) { return escalationStubProvider{}, nil },
-		nil,
-	)
-	if sessionSwitcher != nil {
-		t.Error("a run that did not start with optimized turn sessions was given a session switcher")
-	}
-}
-
-// No provider factory means no escalation rather than a switcher that panics.
-func TestEscalationSwitchersRequireAProviderFactory(t *testing.T) {
-	switcher, sessionSwitcher := EscalationSwitchers(config.ProviderProfile{}, escalationStubProvider{}, nil, nil)
-	if switcher != nil || sessionSwitcher != nil {
-		t.Error("switchers were built without a provider factory to build providers with")
-	}
-}

internal/proxydial/proxydial.go

@@ -0,0 +1,93 @@
+// Package proxydial answers one question for an SSRF-guarded dialer: is this
+// dial the connection dial of a request the transport routed through a forward
+// proxy?
+//
+// A guarded transport validates the TARGET of a request before dialing, and its
+// dialer refuses loopback, private and link-local addresses so a redirect or a
+// DNS rebind cannot walk the request onto the local network. When a forward
+// proxy is configured, the transport dials the PROXY first and tunnels the
+// request through it, and a local proxy is by far the common shape:
+// HTTPS_PROXY=http://127.0.0.1:3067. The dialer then sees 127.0.0.1, refuses it,
+// and the user gets "loopback hosts are blocked" for a request whose real target
+// was validated and public (#569).
+//
+// The proxy address is not the request target, and the guard was never about it.
+// It is configuration the user set on purpose, and the transport is going to dial
+// it for every request whether the guard likes it or not. So that dial is let
+// through, and only that dial.
+//
+// THE EXEMPTION FOLLOWS THE TRANSPORT'S OWN ROUTE DECISION, NOT A GUESS AT IT.
+// Asking the Proxy function a question of one's own invention answers for a
+// request the transport never made: with NO_PROXY excluding a host, the real
+// request to that host goes direct while a synthetic probe still comes back
+// proxied, and a direct dial whose address happens to equal the proxy endpoint
+// would then skip the guard entirely. Host-dependent proxy callbacks make the
+// mismatch general, and no amount of care over the probe's spelling closes it,
+// because the two calls are about different requests.
+//
+// So the decision is recorded where it is made, on the request, and read back on
+// the dial that request causes. Transport.RoundTrip asks the wrapped transport's
+// Proxy function about the actual request, stores the answer in that request's
+// context, and hands it on; the transport derives the dial context from the
+// request context, so the dialer reads back the route this very connection is
+// being opened for. Per-request, so concurrent requests cannot overwrite each
+// other, and unforgeable from outside the package: the context key is private.
+package proxydial
+
+import (
+	"context"
+	"net/http"
+	"net/url"
+)
+
+// selectedProxyKey addresses the route decision inside a request context. It is
+// unexported so nothing outside this package can plant one.
+type selectedProxyKey struct{}
+
+// Transport records the proxy its wrapped transport selects for each request in
+// that request's context, so a guarded DialContext installed on the same
+// transport can tell the dial to a proxy from a direct dial.
+//
+// The embedded transport stays reachable: callers configure Proxy, DialContext
+// and the rest on it exactly as before, and tests can read them back.
+type Transport struct {
+	*http.Transport
+}
+
+// Wrap returns a Transport around transport. The result is the http.RoundTripper
+// to install on the client; installing the bare transport instead leaves every
+// dial looking direct, which is safe (the guard applies) but reopens #569.
+func Wrap(transport *http.Transport) *Transport {
+	return &Transport{Transport: transport}
+}
+
+// RoundTrip resolves the route for this request and passes the decision down to
+// the dialer through the request context.
+func (transport *Transport) RoundTrip(request *http.Request) (*http.Response, error) {
+	if transport.Transport.Proxy != nil {
+		// A Proxy error is left for the transport to report: it fails the
+		// request before dialing, so there is no dial to classify. The function
+		// is called once here and once by the transport, which is what a
+		// host-dependent callback already expects from redirects and retries.
+		if proxyURL, err := transport.Transport.Proxy(request); err == nil && proxyURL != nil {
+			request = request.WithContext(context.WithValue(request.Context(), selectedProxyKey{}, proxyURL))
+		}
+	}
+	return transport.Transport.RoundTrip(request)
+}
+
+// IsProxyDial reports whether ctx belongs to a request this package's Transport
+// routed through a proxy, which makes the dial about to happen the dial to that
+// proxy.
+//
+// THE ADDRESS IS NOT COMPARED, AND DOES NOT NEED TO BE. A transport opens
+// exactly one connection dial per connection, and when a proxy is selected that
+// dial goes to the proxy; the target is reached through it, never dialed. So the
+// route decision on the context already identifies the dial, and matching the
+// address against the proxy URL on top of it could only ever disagree with the
+// transport, which is what a punycoded Unicode proxy hostname does: Go dials
+// xn--bro-hoa.example while the URL still spells buero as the user wrote it.
+func IsProxyDial(ctx context.Context) bool {
+	proxyURL, _ := ctx.Value(selectedProxyKey{}).(*url.URL)
+	return proxyURL != nil
+}

internal/proxydial/proxydial_test.go

@@ -0,0 +1,224 @@
+package proxydial
+
+import (
+	"context"
+	"errors"
+	"net"
+	"net/http"
+	"net/url"
+	"sync"
+	"testing"
+)
+
+// errDialed ends the request at the dial, after the route decision has been
+// observed. Nothing here needs a live server.
+var errDialed = errors.New("dial recorded")
+
+type dialRecord struct {
+	address string
+	proxied bool
+}
+
+// driveRequest sends one request through a wrapped transport whose dialer
+// records what it was asked for and whether the context says this dial belongs
+// to a proxied request.
+func driveRequest(t *testing.T, target string, proxyFor func(*http.Request) (*url.URL, error)) dialRecord {
+	t.Helper()
+	var record dialRecord
+	transport := &http.Transport{Proxy: proxyFor}
+	transport.DialContext = func(ctx context.Context, _, address string) (net.Conn, error) {
+		record = dialRecord{address: address, proxied: IsProxyDial(ctx)}
+		return nil, errDialed
+	}
+	client := &http.Client{Transport: Wrap(transport)}
+	request, err := http.NewRequest(http.MethodGet, target, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := client.Do(request); !errors.Is(err, errDialed) {
+		t.Fatalf("%s: request ended before the dial: %v", target, err)
+	}
+	if record.address == "" {
+		t.Fatalf("%s: the dialer was never called", target)
+	}
+	return record
+}
+
+func fixedProxy(raw string) func(*http.Request) (*url.URL, error) {
+	parsed, err := url.Parse(raw)
+	if err != nil {
+		panic(err)
+	}
+	return func(*http.Request) (*url.URL, error) { return parsed, nil }
+}
+
+// THE DIAL TO A CONFIGURED PROXY IS THE ONE THAT IS EXEMPT. A proxied request
+// dials the proxy, never the target, so the route on the context is what
+// identifies the dial.
+func TestProxiedRequestDialsTheProxyAndSaysSo(t *testing.T) {
+	record := driveRequest(t, "https://api.example.com/v1/models", fixedProxy("http://127.0.0.1:3067"))
+	if !record.proxied {
+		t.Error("a request routed through a proxy did not reach the dialer as proxied")
+	}
+	if record.address != "127.0.0.1:3067" {
+		t.Errorf("dial address = %q, want the proxy endpoint", record.address)
+	}
+}
+
+// AND A DIRECT REQUEST IS NOT, EVEN WHEN ITS ORIGIN IS THE PROXY'S OWN ADDRESS.
+//
+// This is the NO_PROXY shape: the proxy function excludes one host, so a request
+// to that host goes direct. Asking that same function about a request of our own
+// invention would answer "proxied" (the invented host is not excluded) and the
+// direct dial, whose address equals the proxy endpoint, would skip the guard
+// while resolving to whatever the name resolves to at connect time.
+func TestDirectRequestToTheProxyEndpointIsNotAProxyDial(t *testing.T) {
+	proxyURL, err := url.Parse("http://rebind.example:80")
+	if err != nil {
+		t.Fatal(err)
+	}
+	noProxyForRebind := func(request *http.Request) (*url.URL, error) {
+		if request.URL.Hostname() == "rebind.example" {
+			return nil, nil
+		}
+		return proxyURL, nil
+	}
+
+	record := driveRequest(t, "http://rebind.example/data", noProxyForRebind)
+	if record.address != "rebind.example:80" {
+		t.Fatalf("SETUP INVALID: dial address = %q, want the direct origin, which is also the proxy endpoint", record.address)
+	}
+	if record.proxied {
+		t.Error("a direct dial was reported as the proxy dial because its address matched the configured proxy")
+	}
+
+	// The same function still routes another host through that proxy, so the
+	// exclusion above is a route difference and not a disabled proxy.
+	if record := driveRequest(t, "http://elsewhere.example/data", noProxyForRebind); !record.proxied {
+		t.Error("the configured proxy was not used for a host outside the exclusion")
+	}
+}
+
+// The inverse mismatch: a callback that routes by host must not have its answer
+// taken from some other host. A proxy selected only for the real target is
+// honoured.
+func TestHostDependentProxySelectionIsHonoured(t *testing.T) {
+	proxyURL, err := url.Parse("http://127.0.0.1:3067")
+	if err != nil {
+		t.Fatal(err)
+	}
+	onlyForOneHost := func(request *http.Request) (*url.URL, error) {
+		if request.URL.Hostname() == "api.example.com" {
+			return proxyURL, nil
+		}
+		return nil, nil
+	}
+	if record := driveRequest(t, "https://api.example.com/v1", onlyForOneHost); !record.proxied || record.address != "127.0.0.1:3067" {
+		t.Errorf("selected proxy not reached: %+v", record)
+	}
+	if record := driveRequest(t, "https://other.example/v1", onlyForOneHost); record.proxied {
+		t.Error("an unproxied host was reported as proxied")
+	}
+}
+
+// Scheme separation: an https-only proxy leaves an http request direct, and the
+// decision recorded is the one made for that request's own scheme.
+func TestSchemeSeparation(t *testing.T) {
+	proxyURL, err := url.Parse("http://127.0.0.1:3067")
+	if err != nil {
+		t.Fatal(err)
+	}
+	httpsOnly := func(request *http.Request) (*url.URL, error) {
+		if request.URL.Scheme == "https" {
+			return proxyURL, nil
+		}
+		return nil, nil
+	}
+	if record := driveRequest(t, "https://api.example.com/v1", httpsOnly); !record.proxied {
+		t.Error("the https proxy was not applied to an https request")
+	}
+	if record := driveRequest(t, "http://api.example.com/v1", httpsOnly); record.proxied {
+		t.Error("an http request was treated as proxied by an https-only proxy")
+	}
+}
+
+// A UNICODE PROXY HOSTNAME IS STILL THE PROXY. Go dials proxies by their
+// IDNA-encoded name, so a matcher comparing the URL's own spelling would call
+// this dial direct and refuse it as an ordinary private address. Nothing is
+// compared here, so both spellings of one host are one host.
+func TestUnicodeProxyHostnameIsRecognised(t *testing.T) {
+	unicodeRecord := driveRequest(t, "https://api.example.com/v1", fixedProxy("http://büro.example:3067"))
+	if !unicodeRecord.proxied {
+		t.Error("a proxy configured with a Unicode hostname was not recognised as the proxy")
+	}
+	asciiRecord := driveRequest(t, "https://api.example.com/v1", fixedProxy("http://xn--bro-hoa.example:3067"))
+	if !asciiRecord.proxied {
+		t.Error("a proxy configured with the ASCII spelling was not recognised as the proxy")
+	}
+	// The two spellings name one endpoint, and it is the ASCII one that is
+	// dialed. This is the mismatch a string comparison would have had to close.
+	if unicodeRecord.address != asciiRecord.address {
+		t.Errorf("dial addresses differ across spellings of one host: %q vs %q", unicodeRecord.address, asciiRecord.address)
+	}
+}
+
+// A transport with no proxy leaves every dial direct.
+func TestNoProxyMeansNoExemption(t *testing.T) {
+	if record := driveRequest(t, "http://127.0.0.1:3067/", nil); record.proxied {
+		t.Error("a dial was reported as proxied by a transport with no Proxy function")
+	}
+	if IsProxyDial(context.Background()) {
+		t.Error("a context that never went through the wrapper reported a proxy dial")
+	}
+}
+
+// THE DECISION IS PER REQUEST. A shared record of the last selected proxy would
+// let a proxied request hand its exemption to a direct one running beside it.
+func TestConcurrentRequestsKeepTheirOwnRoute(t *testing.T) {
+	proxyURL, err := url.Parse("http://127.0.0.1:3067")
+	if err != nil {
+		t.Fatal(err)
+	}
+	byHost := func(request *http.Request) (*url.URL, error) {
+		if request.URL.Hostname() == "proxied.example" {
+			return proxyURL, nil
+		}
+		return nil, nil
+	}
+
+	var mutex sync.Mutex
+	seen := map[string]bool{}
+	transport := &http.Transport{Proxy: byHost}
+	transport.DialContext = func(ctx context.Context, _, address string) (net.Conn, error) {
+		mutex.Lock()
+		seen[address] = IsProxyDial(ctx)
+		mutex.Unlock()
+		return nil, errDialed
+	}
+	client := &http.Client{Transport: Wrap(transport)}
+
+	var group sync.WaitGroup
+	for range 40 {
+		for _, target := range []string{"http://proxied.example/", "http://direct.example/"} {
+			group.Add(1)
+			go func() {
+				defer group.Done()
+				request, _ := http.NewRequest(http.MethodGet, target, nil)
+				_, _ = client.Do(request)
+			}()
+		}
+	}
+	group.Wait()
+
+	mutex.Lock()
+	defer mutex.Unlock()
+	if !seen["127.0.0.1:3067"] {
+		t.Error("the proxy dial was not recorded as proxied under concurrency")
+	}
+	if seen["direct.example:80"] {
+		t.Error("a direct dial picked up another request's proxy exemption")
+	}
+	if len(seen) != 2 {
+		t.Fatalf("SETUP INVALID: dialed %v, want exactly the proxy and the direct origin", seen)
+	}
+}

internal/tools/web_fetch.go

@@ -13,6 +13,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/Gitlawb/zero/internal/proxydial"
 	"github.com/Gitlawb/zero/internal/redaction"
 	zeroSandbox "github.com/Gitlawb/zero/internal/sandbox"
 )
@@ -308,19 +309,48 @@ func webFetchSafeTransport(roundTripper http.RoundTripper, resolver webFetchReso
 		transport = http.DefaultTransport.(*http.Transport).Clone()
 	case *http.Transport:
 		transport = typed.Clone()
+	case *proxydial.Transport:
+		// Already guarded: rebuild from the inner transport so a second pass
+		// installs one dialer rather than nesting wrappers.
+		transport = typed.Transport.Clone()
 	default:
 		return roundTripper
 	}
 
 	dialer := &net.Dialer{Timeout: webFetchTimeout, KeepAlive: 30 * time.Second}
-	transport.Proxy = nil
+	// THE PROXY IS HONOURED, AND THAT IS A DELIBERATE REVERSAL. The original
+	// guarded fetch set Proxy to nil as part of tightening the SSRF guardrails,
+	// and the reasoning was sound as far as it went: a proxied request is dialed
+	// to the proxy, so the dial-time address pin below never sees the target and
+	// the DNS-rebind protection it provides does not apply. What that traded away
+	// was every fetch on a machine that reaches the network only through a
+	// configured proxy, which fails outright rather than degrades (#569).
+	//
+	// The target is still validated before the request is made, lexically and
+	// through the resolver, with the same block list the dialer applies. What a
+	// forward proxy removes is only the re-check at dial time, and that is
+	// inherent to using any forward proxy; a user who sets HTTPS_PROXY has chosen
+	// it.
+	//
+	// The returned round tripper is wrapped so the dialer learns which route
+	// the transport chose for each request: the one dial it lets past the guard
+	// is the one this transport opens to the proxy it picked for that request.
+	transport.Proxy = http.ProxyFromEnvironment
 	transport.DialContext = webFetchSafeDialContext(resolver, dialer)
 	transport.DialTLSContext = nil
-	return transport
+	return proxydial.Wrap(transport)
 }
 
 func webFetchSafeDialContext(resolver webFetchResolver, dialer webFetchDialer) func(context.Context, string, string) (net.Conn, error) {
 	return func(ctx context.Context, network string, address string) (net.Conn, error) {
+		// The proxy is not the target. See webFetchSafeTransport for why the
+		// proxy is honoured at all; here, the dial the transport opens to the
+		// proxy it selected for this request skips the pin, and nothing else
+		// does. A direct dial is pinned as it always was, including one whose
+		// address happens to equal a configured proxy endpoint.
+		if proxydial.IsProxyDial(ctx) {
+			return dialer.DialContext(ctx, network, address)
+		}
 		pinnedAddress, err := webFetchSafeDialAddress(ctx, resolver, address)
 		if err != nil {
 			return nil, err

internal/tools/web_fetch_proxy_test.go

@@ -0,0 +1,163 @@
+package tools
+
+import (
+	"context"
+	"errors"
+	"net"
+	"net/http"
+	"net/netip"
+	"net/url"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/Gitlawb/zero/internal/proxydial"
+)
+
+// webFetchTransportWithProxy builds the guarded web_fetch round tripper and
+// swaps in a proxy function, which is how the transport learns its route. The
+// environment is left alone deliberately: http.ProxyFromEnvironment reads it
+// once per process, so an environment-driven test would depend on test order.
+func webFetchTransportWithProxy(t *testing.T, resolver webFetchResolver, proxyFor func(*http.Request) (*url.URL, error)) *proxydial.Transport {
+	t.Helper()
+	roundTripper := webFetchSafeTransport(nil, resolver)
+	wrapped, ok := roundTripper.(*proxydial.Transport)
+	if !ok {
+		t.Fatalf("transport = %T, want the route-recording wrapper; without it no dial can be recognised as the proxy dial", roundTripper)
+	}
+	wrapped.Proxy = proxyFor
+	return wrapped
+}
+
+// THE PROXY IS NOT THE TARGET. With HTTPS_PROXY pointing at a local forward
+// proxy, the transport dials the proxy and tunnels the request through it. The
+// dialer used to refuse that dial as a loopback address, so every fetch on a
+// machine behind such a proxy failed with "loopback hosts are blocked" for a
+// public target that had already been validated (#569).
+func TestWebFetchTunnelsThroughTheConfiguredProxy(t *testing.T) {
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer listener.Close()
+	arrived := make(chan string, 1)
+	go func() {
+		conn, err := listener.Accept()
+		if err != nil {
+			return
+		}
+		defer conn.Close()
+		buffer := make([]byte, 256)
+		n, _ := conn.Read(buffer)
+		arrived <- string(buffer[:n])
+	}()
+	proxyURL, err := url.Parse("http://" + listener.Addr().String())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// A proxied fetch never resolves the target on this side; the CONNECT
+	// carries the hostname and the proxy resolves it.
+	transport := webFetchTransportWithProxy(t,
+		webFetchResolverFunc(func(context.Context, string, string) ([]netip.Addr, error) {
+			return nil, errors.New("resolver must not be called for a proxied fetch")
+		}),
+		func(*http.Request) (*url.URL, error) { return proxyURL, nil })
+	client := &http.Client{Transport: transport, Timeout: 3 * time.Second}
+
+	_, err = client.Get("https://public.example/resource")
+	select {
+	case first := <-arrived:
+		if line := strings.SplitN(first, "\r\n", 2)[0]; line != "CONNECT public.example:443 HTTP/1.1" {
+			t.Fatalf("proxy received %q, want a CONNECT for the target", line)
+		}
+	case <-time.After(5 * time.Second):
+		t.Fatalf("the proxy never received a connection; request error: %v", err)
+	}
+}
+
+// AND A DIRECT FETCH STAYS PINNED, EVEN WHEN ITS ORIGIN IS THE PROXY'S OWN
+// ADDRESS.
+//
+// This is the NO_PROXY shape: the proxy function sends one host direct. An
+// exemption derived from asking that function about a request of our own
+// invention would answer "proxied" for the excluded host too, and this dial
+// would skip the pin and reach whatever the name resolves to at connect time.
+func TestWebFetchDirectRequestToTheProxyEndpointIsStillPinned(t *testing.T) {
+	proxyURL, err := url.Parse("http://rebind.example:80")
+	if err != nil {
+		t.Fatal(err)
+	}
+	lookups := 0
+	transport := webFetchTransportWithProxy(t,
+		webFetchResolverFunc(func(_ context.Context, _ string, host string) ([]netip.Addr, error) {
+			lookups++
+			return []netip.Addr{netip.MustParseAddr("127.0.0.1")}, nil
+		}),
+		func(request *http.Request) (*url.URL, error) {
+			if request.URL.Hostname() == "rebind.example" {
+				return nil, nil
+			}
+			return proxyURL, nil
+		})
+	client := &http.Client{Transport: transport, Timeout: 3 * time.Second}
+
+	_, err = client.Get("http://rebind.example/data")
+
+	if lookups == 0 {
+		t.Fatal("the direct dial skipped the address pin because its address matched the configured proxy endpoint")
+	}
+	if err == nil || !strings.Contains(err.Error(), "loopback hosts are blocked") {
+		t.Fatalf("err = %v, want the private answer to be refused", err)
+	}
+}
+
+// A proxy configured with a Unicode hostname is dialed by its IDNA-encoded
+// name, and it is still the proxy.
+func TestWebFetchUnicodeProxyHostnameIsStillTheProxy(t *testing.T) {
+	dialed := ""
+	transport := webFetchTransportWithProxy(t,
+		webFetchResolverFunc(func(context.Context, string, string) ([]netip.Addr, error) {
+			return nil, errors.New("resolver must not be called for a proxied fetch")
+		}),
+		func(*http.Request) (*url.URL, error) { return url.Parse("http://büro.example:3067") })
+	guarded := transport.DialContext
+	transport.DialContext = func(ctx context.Context, network, address string) (net.Conn, error) {
+		dialed = address
+		return guarded(ctx, network, address)
+	}
+	client := &http.Client{Transport: transport, Timeout: 3 * time.Second}
+
+	_, err := client.Get("https://public.example/resource")
+
+	if dialed != "xn--bro-hoa.example:3067" {
+		t.Fatalf("SETUP INVALID: dialed %q, want the IDNA-encoded proxy endpoint", dialed)
+	}
+	if err != nil && strings.Contains(err.Error(), "hosts are blocked") {
+		t.Fatalf("the configured proxy was refused by the guard: %v", err)
+	}
+}
+
+// Without a proxy the guard is exactly what it was: loopback is refused and
+// the dialer never runs.
+func TestWebFetchSafeDialStillRefusesLoopbackWithoutAProxy(t *testing.T) {
+	dialCalled := false
+	dial := webFetchSafeDialContext(
+		webFetchResolverFunc(func(_ context.Context, network string, host string) ([]netip.Addr, error) {
+			t.Fatalf("resolver consulted for a loopback literal: network=%q host=%q", network, host)
+			return nil, nil
+		}),
+		webFetchDialFunc(func(context.Context, string, string) (net.Conn, error) {
+			dialCalled = true
+			return nil, errors.New("dial should not run")
+		}),
+	)
+
+	_, err := dial(context.Background(), "tcp", "127.0.0.1:3067")
+	if err == nil || !strings.Contains(err.Error(), "loopback hosts are blocked") {
+		t.Fatalf("expected loopback rejection, got %v", err)
+	}
+	if dialCalled {
+		t.Fatal("loopback was dialed with no proxy configured")
+	}
+}

internal/tools/web_fetch_test.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/Gitlawb/zero/internal/proxydial"
 	zeroSandbox "github.com/Gitlawb/zero/internal/sandbox"
 )
 
@@ -325,15 +326,26 @@ func TestWebFetchToolConfiguresDialTimeSafetyForDefaultTransport(t *testing.T) {
 	}
 
 	client := tool.clientForRun()
-	transport, ok := client.Transport.(*http.Transport)
+	// The round tripper is the route-recording wrapper, not the bare transport:
+	// it is what tells the dialer which dial is the one to the proxy the
+	// transport picked for a given request. The guarded transport it wraps
+	// stays reachable, and is what the rest of this test inspects.
+	transport, ok := client.Transport.(*proxydial.Transport)
 	if !ok {
-		t.Fatalf("client transport = %T, want *http.Transport", client.Transport)
+		t.Fatalf("client transport = %T, want *proxydial.Transport", client.Transport)
 	}
 	if transport.DialContext == nil {
 		t.Fatal("expected web_fetch transport to install a safe DialContext")
 	}
-	if transport.Proxy != nil {
-		t.Fatal("expected web_fetch transport to disable proxy resolution")
+	// REVERSED ON PURPOSE. The guarded fetch used to pin Proxy to nil as part of
+	// the SSRF hardening, and this assertion held it there. #569 is what that
+	// cost: on a machine that reaches the network only through a configured
+	// forward proxy, every fetch failed outright. The proxy is honoured now, and
+	// the wrapper hands the dialer the route chosen for each request so the one
+	// dial it lets past the guard is the one to that proxy. The target is still
+	// validated before the request, which the tests below pin.
+	if transport.Proxy == nil {
+		t.Fatal("expected web_fetch transport to honour the environment proxy; a machine behind a forward proxy cannot fetch at all without it (#569)")
 	}
 }
 

internal/tui/escalation_usage_test.go

@@ -1,303 +0,0 @@
-package tui
-
-import (
-	"context"
-	"encoding/json"
-	"reflect"
-	"testing"
-
-	tea "charm.land/bubbletea/v2"
-
-	"github.com/Gitlawb/zero/internal/config"
-	"github.com/Gitlawb/zero/internal/modelregistry"
-	"github.com/Gitlawb/zero/internal/sessions"
-	"github.com/Gitlawb/zero/internal/tools"
-	"github.com/Gitlawb/zero/internal/usage"
-	"github.com/Gitlawb/zero/internal/zeroruntime"
-)
-
-// USAGE FOLLOWS THE SWITCH. exec reassigns its currentModel when the escalation
-// switcher fires; the TUI captured usageModelID once per run and handed the
-// switcher no callback, so every usage event after an escalation was billed to
-// the model the run started on. Both attribution paths are pinned here: the
-// live per-event message, and the per-event record the final response carries
-// for the batch fallback, which must not swing the other way and bill the
-// events before the switch to the escalated model.
-func TestEscalatedRunAttributesUsageToTheModelInForce(t *testing.T) {
-	store := testSessionStore(t)
-	session, err := store.Create(sessions.CreateInput{SessionID: "escalation_usage"})
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	// A catalog model with an upgrade target; the target is whatever the
-	// catalog says, read back from the provider factory rather than assumed.
-	const startModel = "claude-haiku-4.5"
-	starting := &scriptedProvider{scripts: [][]zeroruntime.StreamEvent{{
-		{Type: zeroruntime.StreamEventUsage, Usage: zeroruntime.Usage{InputTokens: 10, OutputTokens: 1}},
-		{Type: zeroruntime.StreamEventToolCallStart, ToolCallID: "escalate", ToolName: "escalate_model"},
-		{Type: zeroruntime.StreamEventToolCallDelta, ToolCallID: "escalate", ArgumentsFragment: `{"reason":"harder than it looked"}`},
-		{Type: zeroruntime.StreamEventToolCallEnd, ToolCallID: "escalate"},
-		{Type: zeroruntime.StreamEventDone},
-	}}}
-	escalated := &scriptedProvider{scripts: [][]zeroruntime.StreamEvent{{
-		{Type: zeroruntime.StreamEventText, Content: "Done on the stronger model."},
-		{Type: zeroruntime.StreamEventUsage, Usage: zeroruntime.Usage{InputTokens: 20, OutputTokens: 2}},
-		{Type: zeroruntime.StreamEventDone},
-	}}}
-	registry := tools.NewRegistry()
-	registry.Register(tools.NewEscalateModelTool())
-
-	switchedTo := ""
-	m := newModel(context.Background(), Options{
-		ProviderName:    "anthropic",
-		ModelName:       startModel,
-		Provider:        starting,
-		Registry:        registry,
-		SessionStore:    store,
-		AllowEscalation: true,
-		ProviderProfile: config.ProviderProfile{Model: startModel},
-		NewProvider: func(profile config.ProviderProfile) (zeroruntime.Provider, error) {
-			switchedTo = profile.Model
-			return escalated, nil
-		},
-	})
-	m.activeSession = session
-	m.agentOptions.Model = startModel
-	var live []string
-	m.runtimeMessageSink = func(msg tea.Msg) {
-		if usage, ok := msg.(agentUsageMsg); ok {
-			live = append(live, usage.modelID)
-		}
-	}
-
-	msg := execCmd(m.runAgentWithOptions(1, context.Background(), "do the hard thing", nil, tuiAgentRunOptions{}))
-	response, ok := msg.(agentResponseMsg)
-	if !ok {
-		t.Fatalf("run returned %T, want agentResponseMsg", msg)
-	}
-	if response.err != nil {
-		t.Fatalf("run failed: %v", response.err)
-	}
-	if switchedTo == "" || switchedTo == startModel {
-		t.Fatalf("SETUP INVALID: the escalation never switched providers (switched to %q), so nothing here exercises attribution", switchedTo)
-	}
-	if len(escalated.requests) == 0 {
-		t.Fatal("SETUP INVALID: the escalated provider was never asked for a completion")
-	}
-	if len(response.usageEvents) != 2 {
-		t.Fatalf("usage events = %d, want one before the switch and one after", len(response.usageEvents))
-	}
-
-	want := []string{startModel, switchedTo}
-	if !reflect.DeepEqual(live, want) {
-		t.Fatalf("live usage attribution = %v, want %v", live, want)
-	}
-	if !reflect.DeepEqual(response.usageModelIDs, want) {
-		t.Fatalf("per-event usage attribution on the response = %v, want %v", response.usageModelIDs, want)
-	}
-	for index := range response.usageEvents {
-		if got := response.usageModelIDAt(index); got != want[index] {
-			t.Fatalf("usageModelIDAt(%d) = %q, want %q", index, got, want[index])
-		}
-	}
-}
-
-// A response built without the per-event record, which is every constructor
-// that predates escalation, still attributes through the run-level model.
-func TestUsageModelIDAtFallsBackToTheRunModel(t *testing.T) {
-	msg := agentResponseMsg{usageModelID: "gpt-4.1", usageEvents: make([]zeroruntime.Usage, 2)}
-	for index := range msg.usageEvents {
-		if got := msg.usageModelIDAt(index); got != "gpt-4.1" {
-			t.Fatalf("usageModelIDAt(%d) = %q, want the run-level model", index, got)
-		}
-	}
-	msg.usageModelIDs = []string{"gpt-4.1-mini"}
-	if got := msg.usageModelIDAt(0); got != "gpt-4.1-mini" {
-		t.Fatalf("usageModelIDAt(0) = %q, want the per-event model", got)
-	}
-	if got := msg.usageModelIDAt(1); got != "gpt-4.1" {
-		t.Fatalf("usageModelIDAt(1) = %q, want the run-level fallback past the record", got)
-	}
-}
-
-// AND THE PRICE THAT COMES BACK OUT OF THE SESSION LOG. The live record and the
-// persisted event are two representations of one usage event, and only the
-// first carried the model. `zero usage report` rebuilds cost from the persisted
-// payload, falling back to the session's own model when the event does not name
-// one, so an escalated run was priced end to end at the model it started on.
-// This drives the real persistence path and reconstructs the report from it.
-func TestEscalatedRunPricesPersistedUsageAtEachModel(t *testing.T) {
-	registry, err := modelregistry.DefaultRegistry()
-	if err != nil {
-		t.Fatal(err)
-	}
-	store := testSessionStore(t)
-	session, err := store.Create(sessions.CreateInput{SessionID: "escalation_cost"})
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	const startModel = "claude-haiku-4.5"
-	before := zeroruntime.Usage{InputTokens: 10, OutputTokens: 1}
-	after := zeroruntime.Usage{InputTokens: 20, OutputTokens: 2}
-	starting := &scriptedProvider{scripts: [][]zeroruntime.StreamEvent{{
-		{Type: zeroruntime.StreamEventUsage, Usage: before},
-		{Type: zeroruntime.StreamEventToolCallStart, ToolCallID: "escalate", ToolName: "escalate_model"},
-		{Type: zeroruntime.StreamEventToolCallDelta, ToolCallID: "escalate", ArgumentsFragment: `{"reason":"harder than it looked"}`},
-		{Type: zeroruntime.StreamEventToolCallEnd, ToolCallID: "escalate"},
-		{Type: zeroruntime.StreamEventDone},
-	}}}
-	escalated := &scriptedProvider{scripts: [][]zeroruntime.StreamEvent{{
-		{Type: zeroruntime.StreamEventText, Content: "Done on the stronger model."},
-		{Type: zeroruntime.StreamEventUsage, Usage: after},
-		{Type: zeroruntime.StreamEventDone},
-	}}}
-	toolRegistry := tools.NewRegistry()
-	toolRegistry.Register(tools.NewEscalateModelTool())
-
-	switchedTo := ""
-	m := newModel(context.Background(), Options{
-		ProviderName:    "anthropic",
-		ModelName:       startModel,
-		Provider:        starting,
-		Registry:        toolRegistry,
-		SessionStore:    store,
-		AllowEscalation: true,
-		ProviderProfile: config.ProviderProfile{Model: startModel},
-		NewProvider: func(profile config.ProviderProfile) (zeroruntime.Provider, error) {
-			switchedTo = profile.Model
-			return escalated, nil
-		},
-	})
-	m.activeSession = session
-	m.agentOptions.Model = startModel
-
-	msg := execCmd(m.runAgentWithOptions(1, context.Background(), "do the hard thing", nil, tuiAgentRunOptions{}))
-	response, ok := msg.(agentResponseMsg)
-	if !ok || response.err != nil {
-		t.Fatalf("run returned %T err=%v", msg, response.err)
-	}
-	if switchedTo == "" || switchedTo == startModel {
-		t.Fatalf("SETUP INVALID: no escalation happened (switched to %q)", switchedTo)
-	}
-
-	// Persist through the same path a real run uses, then read the events back.
-	m, rows := m.appendSessionEvents(response.sessionEvents)
-	for _, row := range rows {
-		if row.kind == rowError {
-			t.Fatalf("session record error: %s", row.text)
-		}
-	}
-	events, err := store.ReadEvents(session.SessionID)
-	if err != nil {
-		t.Fatal(err)
-	}
-	persisted := []string{}
-	for _, event := range events {
-		if event.Type != sessions.EventUsage {
-			continue
-		}
-		var payload struct {
-			Model string `json:"model"`
-		}
-		if err := json.Unmarshal(event.Payload, &payload); err != nil {
-			t.Fatal(err)
-		}
-		persisted = append(persisted, payload.Model)
-	}
-	if want := []string{startModel, switchedTo}; !reflect.DeepEqual(persisted, want) {
-		t.Fatalf("persisted usage models = %v, want %v", persisted, want)
-	}
-
-	// The report prices from those payloads. Its session metadata names only the
-	// starting model, which is the fallback that used to price both events.
-	metadata := []sessions.Metadata{{SessionID: session.SessionID, ModelID: startModel}}
-	report, err := usage.BuildReport(events, metadata, &registry, 0)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	// Expected cost comes from the catalog, one completion at each model.
-	expected := 0.0
-	for _, priced := range []struct {
-		modelID string
-		usage   zeroruntime.Usage
-	}{{startModel, before}, {switchedTo, after}} {
-		model, err := registry.Require(priced.modelID)
-		if err != nil {
-			t.Fatal(err)
-		}
-		cost, err := modelregistry.CalculateCost(model, priced.usage)
-		if err != nil {
-			t.Fatal(err)
-		}
-		expected += cost.TotalCost
-	}
-	// And the wrong answer, for contrast: both events at the starting model.
-	startingOnly := 0.0
-	startingEntry, err := registry.Require(startModel)
-	if err != nil {
-		t.Fatal(err)
-	}
-	for _, event := range []zeroruntime.Usage{before, after} {
-		cost, err := modelregistry.CalculateCost(startingEntry, event)
-		if err != nil {
-			t.Fatal(err)
-		}
-		startingOnly += cost.TotalCost
-	}
-	if expected == startingOnly {
-		t.Fatal("SETUP INVALID: the two models price this usage identically, so the assertion below proves nothing")
-	}
-	if difference := report.Total.TotalCost - expected; difference > 1e-12 || difference < -1e-12 {
-		t.Fatalf("report cost = %v, want %v (pricing both events at %s gives %v)", report.Total.TotalCost, expected, startModel, startingOnly)
-	}
-}
-
-// A run without escalation persists no model on its usage events: the model
-// cannot change mid-run, so the session-wide identity is the whole story and
-// the payload stays compact, exactly as exec does it.
-func TestUnescalatedRunLeavesTheUsagePayloadAlone(t *testing.T) {
-	store := testSessionStore(t)
-	session, err := store.Create(sessions.CreateInput{SessionID: "no_escalation_usage"})
-	if err != nil {
-		t.Fatal(err)
-	}
-	provider := &scriptedProvider{scripts: [][]zeroruntime.StreamEvent{{
-		{Type: zeroruntime.StreamEventText, Content: "done"},
-		{Type: zeroruntime.StreamEventUsage, Usage: zeroruntime.Usage{InputTokens: 10, OutputTokens: 1}},
-		{Type: zeroruntime.StreamEventDone},
-	}}}
-	m := newModel(context.Background(), Options{
-		ProviderName: "anthropic",
-		ModelName:    "claude-haiku-4.5",
-		Provider:     provider,
-		Registry:     tools.NewRegistry(),
-		SessionStore: store,
-	})
-	m.activeSession = session
-
-	msg := execCmd(m.runAgentWithOptions(1, context.Background(), "hello", nil, tuiAgentRunOptions{}))
-	response, ok := msg.(agentResponseMsg)
-	if !ok || response.err != nil {
-		t.Fatalf("run returned %T err=%v", msg, response.err)
-	}
-	usageEvents := 0
-	for _, event := range response.sessionEvents {
-		if event.Type != sessions.EventUsage {
-			continue
-		}
-		usageEvents++
-		payload, ok := event.Payload.(map[string]any)
-		if !ok {
-			t.Fatalf("usage payload = %T, want map", event.Payload)
-		}
-		if _, present := payload["model"]; present {
-			t.Errorf("a non-escalation run recorded a model on its usage payload: %v", payload)
-		}
-	}
-	if usageEvents == 0 {
-		t.Fatal("SETUP INVALID: the run recorded no usage event")
-	}
-}

internal/tui/model.go

@@ -70,24 +70,21 @@ const dragEdgeScrollInterval = 70 * time.Millisecond
 const dragEdgeScrollStep = 1
 
 type model struct {
-	ctx                  context.Context
-	cwd                  string
-	appVersion           string
-	userCommands         []usercommands.Command // file-sourced /commands (.zero/commands)
-	loadSkills           func() []skills.Skill  // lazy installed-skills loader for /skills + /<skill-name>
-	userConfigPath       string
-	doctorUserConfigPath string
-	projectConfigPath    string
-	gitBranch            string
-	providerName         string
-	modelName            string
-	modelCatalog         modelregistry.Registry
-	providerProfile      config.ProviderProfile
-	savedProviders       []config.ProviderProfile
-	provider             zeroruntime.Provider
-	// allowEscalation mirrors Options.AllowEscalation: it gates the per-run model
-	// switchers, and the caller gates the escalate_model tool on the same flag.
-	allowEscalation             bool
+	ctx                         context.Context
+	cwd                         string
+	appVersion                  string
+	userCommands                []usercommands.Command // file-sourced /commands (.zero/commands)
+	loadSkills                  func() []skills.Skill  // lazy installed-skills loader for /skills + /<skill-name>
+	userConfigPath              string
+	doctorUserConfigPath        string
+	projectConfigPath           string
+	gitBranch                   string
+	providerName                string
+	modelName                   string
+	modelCatalog                modelregistry.Registry
+	providerProfile             config.ProviderProfile
+	savedProviders              []config.ProviderProfile
+	provider                    zeroruntime.Provider
 	newProvider                 func(config.ProviderProfile) (zeroruntime.Provider, error)
 	newTurnSessionProvider      func(config.ProviderProfile, zeroruntime.Provider) zeroruntime.TurnSessionProvider
 	probeProviderHealth         func(context.Context, providerhealth.Options) providerhealth.Result
@@ -661,16 +658,10 @@ type agentUsageMsg struct {
 }
 
 type agentResponseMsg struct {
-	runID       int
-	rows        []transcriptRow
-	usageEvents []zeroruntime.Usage
-	// usageModelID is the model in force when the run ended. usageModelIDs is
-	// the model in force when each usageEvents entry fired: a mid-run
-	// escalation changes it partway through the run, and billing the events
-	// before the switch to the escalated model would be as wrong as billing
-	// the ones after it to the starting model. Read through usageModelIDAt.
+	runID         int
+	rows          []transcriptRow
+	usageEvents   []zeroruntime.Usage
 	usageModelID  string
-	usageModelIDs []string
 	sessionEvents []pendingSessionEvent
 	specReview    *pendingSpecReviewPrompt
 	err           error
@@ -683,16 +674,6 @@ type agentResponseMsg struct {
 	ttft time.Duration
 }
 
-// usageModelIDAt is the model in force when usageEvents[index] fired. The
-// per-event record wins; usageModelID is the fallback for a message built
-// without one, which is what every constructor before escalation produced.
-func (msg agentResponseMsg) usageModelIDAt(index int) string {
-	if index < len(msg.usageModelIDs) && msg.usageModelIDs[index] != "" {
-		return msg.usageModelIDs[index]
-	}
-	return msg.usageModelID
-}
-
 type peerMessageMsg struct {
 	message peermsg.InboundMessage
 	admit   chan<- bool
@@ -1018,7 +999,6 @@ func newModel(ctx context.Context, options Options) model {
 		mcpCommand:                  options.MCPCommand,
 		sandboxSetupCommand:         options.SandboxSetupCommand,
 		agentOptions:                options.AgentOptions,
-		allowEscalation:             options.AllowEscalation,
 		sessionCompactor:            options.SessionCompactor,
 		runtimeMessageSink:          options.RuntimeMessageSink,
 		permissionMode:              permissionMode,
@@ -2566,7 +2546,7 @@ func (m model) updateModel(msg tea.Msg) (tea.Model, tea.Cmd) {
 						continue
 					}
 					var usageRows []transcriptRow
-					m, usageRows = m.recordUsageEvent(msg.usageModelIDAt(index), event)
+					m, usageRows = m.recordUsageEvent(msg.usageModelID, event)
 					for _, row := range usageRows {
 						m.transcript = appendTranscriptRow(m.transcript, row)
 					}
@@ -2653,7 +2633,7 @@ func (m model) updateModel(msg tea.Msg) (tea.Model, tea.Cmd) {
 				continue
 			}
 			var usageRows []transcriptRow
-			m, usageRows = m.recordUsageEvent(msg.usageModelIDAt(index), event)
+			m, usageRows = m.recordUsageEvent(msg.usageModelID, event)
 			for _, row := range usageRows {
 				m.transcript = appendTranscriptRow(m.transcript, row)
 			}
@@ -5447,9 +5427,6 @@ func (m model) runAgentWithOptions(runID int, runCtx context.Context, prompt str
 		usageEvents := []zeroruntime.Usage{}
 		sessionEvents := []pendingSessionEvent{}
 		usageModelID := m.modelName
-		// usageModelIDs records, per usage event, the model in force when it
-		// fired; the escalation switcher reassigns usageModelID mid-run.
-		usageModelIDs := []string{}
 		var specReview *pendingSpecReviewPrompt
 		if m.awaitToolReadiness != nil {
 			m.awaitToolReadiness(runCtx)
@@ -5519,27 +5496,6 @@ func (m model) runAgentWithOptions(runID int, runCtx context.Context, prompt str
 		options.ContextWindowFor = func(modelID string) int {
 			return modelregistry.AgentContextWindow(m.modelContextWindow(modelID))
 		}
-		// And make that switch reachable, when the operator asked for it. The
-		// consequences of an escalation were already handled here (the window
-		// above, and the summarizer resolved against the active profile) while
-		// nothing on this surface could cause one: escalate_model was registered
-		// only by exec.
-		//
-		// BUILT FROM THE ACTIVE PROFILE, NOT THE STARTUP ONE. A TUI session can
-		// change models with /model, so escalating from the profile captured at
-		// launch would switch from whatever the session began with rather than
-		// from what is in force now, and would carry that stale profile's base URL
-		// and credential with it. m.providerProfile tracks the switches, which is
-		// why this is built per turn rather than once in the caller.
-		if m.allowEscalation {
-			options.ModelSwitcher, options.ModelSessionSwitcher = providers.EscalationSwitchers(
-				m.providerProfile, m.provider, m.newProvider,
-				// Usage attribution follows the switch, as exec reassigns its
-				// currentModel: every usage event after a real escalation is billed
-				// to the escalated model, not the one the run started on.
-				func(modelID string) { usageModelID = modelID },
-			)
-		}
 
 		// Post-edit self-correction is on by default in the TUI but kept FAST: it
 		// runs LSP diagnostics over the changed files only — cheap, change-scoped,
@@ -5905,20 +5861,9 @@ func (m model) runAgentWithOptions(runID int, runCtx context.Context, prompt str
 		onUsage := options.OnUsage
 		options.OnUsage = func(event zeroruntime.Usage) {
 			usageEvents = append(usageEvents, event)
-			usageModelIDs = append(usageModelIDs, usageModelID)
-			payload := usage.EventUsagePayload(event)
-			// AND ON THE PERSISTED EVENT TOO, not only the in-memory record: the
-			// report reconstructs cost from the payload, falling back to the
-			// session-wide model, so an escalated run would be priced entirely at
-			// the model it started on. Written only under escalation, which is the
-			// only way the model in force can change mid-run, matching what exec
-			// records under the same flag.
-			if m.allowEscalation {
-				payload["model"] = usageModelID
-			}
 			sessionEvents = append(sessionEvents, pendingSessionEvent{
 				Type:    sessions.EventUsage,
-				Payload: payload,
+				Payload: usage.EventUsagePayload(event),
 			})
 			m.sendAgentUsage(runID, usageModelID, event)
 			if onUsage != nil {
@@ -5933,7 +5878,7 @@ func (m model) runAgentWithOptions(runID int, runCtx context.Context, prompt str
 				Type:    sessions.EventError,
 				Payload: map[string]any{"message": err.Error()},
 			})
-			return agentResponseMsg{runID: runID, rows: rows, usageEvents: usageEvents, usageModelID: usageModelID, usageModelIDs: usageModelIDs, sessionEvents: sessionEvents, err: err, goalAware: goalAwareRun, turnTools: toolCalls, turnElapsed: m.activeTurnElapsed(started)}
+			return agentResponseMsg{runID: runID, rows: rows, usageEvents: usageEvents, usageModelID: usageModelID, sessionEvents: sessionEvents, err: err, goalAware: goalAwareRun, turnTools: toolCalls, turnElapsed: m.activeTurnElapsed(started)}
 		}
 		if runOptions.specDraft {
 			if result.StopReason != agent.StopReasonSpecReviewRequired || specReview == nil || specReview.SpecID == "" || specReview.SpecFilePath == "" {
@@ -5943,10 +5888,10 @@ func (m model) runAgentWithOptions(runID int, runCtx context.Context, prompt str
 					Type:    sessions.EventError,
 					Payload: map[string]any{"message": err.Error()},
 				})
-				return agentResponseMsg{runID: runID, rows: rows, usageEvents: usageEvents, usageModelID: usageModelID, usageModelIDs: usageModelIDs, sessionEvents: sessionEvents, err: err, goalAware: goalAwareRun, turnTools: toolCalls, turnElapsed: m.activeTurnElapsed(started)}
+				return agentResponseMsg{runID: runID, rows: rows, usageEvents: usageEvents, usageModelID: usageModelID, sessionEvents: sessionEvents, err: err, goalAware: goalAwareRun, turnTools: toolCalls, turnElapsed: m.activeTurnElapsed(started)}
 			}
 			flushReasoning(m.now())
-			return agentResponseMsg{runID: runID, rows: rows, usageEvents: usageEvents, usageModelID: usageModelID, usageModelIDs: usageModelIDs, sessionEvents: sessionEvents, specReview: specReview, goalAware: goalAwareRun, turnTools: toolCalls, turnElapsed: m.activeTurnElapsed(started)}
+			return agentResponseMsg{runID: runID, rows: rows, usageEvents: usageEvents, usageModelID: usageModelID, sessionEvents: sessionEvents, specReview: specReview, goalAware: goalAwareRun, turnTools: toolCalls, turnElapsed: m.activeTurnElapsed(started)}
 		}
 		flushReasoning(m.now())
 		elapsed := m.activeTurnElapsed(started)
@@ -5967,7 +5912,7 @@ func (m model) runAgentWithOptions(runID int, runCtx context.Context, prompt str
 				"content": result.FinalAnswer,
 			},
 		})
-		return agentResponseMsg{runID: runID, rows: rows, usageEvents: usageEvents, usageModelID: usageModelID, usageModelIDs: usageModelIDs, sessionEvents: sessionEvents, goalAware: goalAwareRun, turnTools: toolCalls, turnElapsed: elapsed, ttft: firstTokenElapsed}
+		return agentResponseMsg{runID: runID, rows: rows, usageEvents: usageEvents, usageModelID: usageModelID, sessionEvents: sessionEvents, goalAware: goalAwareRun, turnTools: toolCalls, turnElapsed: elapsed, ttft: firstTokenElapsed}
 	}
 }
 

internal/tui/options.go

@@ -70,13 +70,7 @@ type Options struct {
 	// invocation. Called lazily per use so newly installed skills are picked up
 	// without a restart. Nil means the session has no skills wiring (skills stay
 	// model-pulled via the skill tool only).
-	LoadSkills func() []skills.Skill
-	// AllowEscalation opts this session into mid-run model escalation, set from
-	// --allow-escalation. It wires the model switchers onto every turn's options;
-	// the escalate_model tool itself is registered by the caller on the same flag.
-	// Both halves are required: the tool without the switchers is inert, and the
-	// switchers without the tool are unreachable.
-	AllowEscalation bool
+	LoadSkills      func() []skills.Skill
 	PermissionMode  agent.PermissionMode
 	ReasoningEffort modelregistry.ReasoningEffort
 	ResponseStyle   string