test(search): make the metadata coverage guard recurse, so nesting cannot slip past it

The first version of the guard walked only the direct string fields of
sessions.Metadata and hand-allocated the Goal beside it. That left it with the
blind spot it exists to close: a nested struct or pointer field added later
would arrive empty, the walk would find nothing in it, and the test would pass
while the new field went out unredacted. Raised by CodeRabbit on the PR.

Filling is now recursive through structs, pointers and slices, allocating what
it finds nil, and the walk is its mirror. The test compares the two counts, so a
shape one traversal understands and the other does not fails as SETUP INVALID
rather than passing quietly.

Both helpers fail rather than skip on a kind they do not understand. A field the
guard cannot populate is a field it is not guarding, and saying so at the point
it is added is the whole value of having it.

internal/providers/anthropic/provider.go

@@ -90,6 +90,7 @@ type Options struct {
 	// When unset, Zero uses providerio.ResolveStreamIdleTimeout — the
 	// ZERO_STREAM_IDLE_TIMEOUT override or providerio.DefaultStreamIdleTimeout.
 	StreamIdleTimeout time.Duration
+	SessionHeader     string
 }
 
 // Provider streams completions from Anthropic's Messages API.
@@ -108,6 +109,7 @@ type Provider struct {
 	httpClient        *http.Client
 	userAgent         string
 	streamIdleTimeout time.Duration
+	sessionHeader     providerio.SessionHeader
 }
 
 // New creates an Anthropic provider.
@@ -143,6 +145,7 @@ func New(options Options) (*Provider, error) {
 		httpClient:        providerio.HTTPClient(options.HTTPClient),
 		userAgent:         options.UserAgent,
 		streamIdleTimeout: providerio.ResolveStreamIdleTimeout(options.StreamIdleTimeout),
+		sessionHeader:     providerio.NewSessionHeader(options.SessionHeader),
 	}, nil
 }
 
@@ -163,12 +166,12 @@ func (provider *Provider) StreamCompletion(
 	events := make(chan zeroruntime.StreamEvent, 16)
 	go func() {
 		defer close(events)
-		provider.stream(ctx, body, events)
+		provider.stream(ctx, body, request.PromptCacheKey, events)
 	}()
 	return events, nil
 }
 
-func (provider *Provider) stream(ctx context.Context, body []byte, events chan<- zeroruntime.StreamEvent) {
+func (provider *Provider) stream(ctx context.Context, body []byte, sessionID string, events chan<- zeroruntime.StreamEvent) {
 	// streamCtx lets the idle watchdog abort an in-flight body read by cancelling
 	// the request, which unblocks the SSE reader goroutine.
 	streamCtx, cancelStream := context.WithCancel(ctx)
@@ -185,6 +188,7 @@ func (provider *Provider) stream(ctx context.Context, body []byte, events chan<-
 		},
 		provider.oauthResolver,
 		func(request *http.Request) {
+			provider.sessionHeader.Apply(request, sessionID)
 			request.Header.Set("Content-Type", "application/json")
 			request.Header.Set("anthropic-version", provider.version)
 			if provider.beta != "" {

internal/providers/factory.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"net/http"
+	"net/url"
 	"strings"
 
 	"github.com/Gitlawb/zero/internal/config"
@@ -53,6 +54,11 @@ func New(profile config.ProviderProfile, options Options) (zeroruntime.Provider,
 		return newCodexProvider(profile, resolved, options)
 	}
 
+	sessionHeader := sessionHeaderForProfile(profile, resolved)
+	if sessionHeader != "" && strings.TrimSpace(options.UserAgent) == "" {
+		options.UserAgent = "zero"
+	}
+
 	switch resolved.providerKind {
 	case config.ProviderKindOpenAI, config.ProviderKindOpenAICompatible:
 		// prompt_cache_key is an OpenAI-only chat-completions field. Strict
@@ -74,6 +80,7 @@ func New(profile config.ProviderProfile, options Options) (zeroruntime.Provider,
 			UserAgent:             options.UserAgent,
 			ParseThinkTags:        parseThinkTagsForProfile(profile, resolved),
 			DisablePromptCacheKey: resolved.providerKind == config.ProviderKindOpenAICompatible,
+			SessionHeader:         sessionHeader,
 		})
 	case config.ProviderKindAnthropic, config.ProviderKindAnthropicCompat:
 		return anthropic.New(anthropic.Options{
@@ -88,6 +95,7 @@ func New(profile config.ProviderProfile, options Options) (zeroruntime.Provider,
 			MaxTokens:       resolved.maxOutputTokens,
 			HTTPClient:      options.HTTPClient,
 			UserAgent:       options.UserAgent,
+			SessionHeader:   sessionHeader,
 		})
 	case config.ProviderKindGoogle:
 		return gemini.New(gemini.Options{
@@ -345,6 +353,18 @@ func isCodexCatalog(profile config.ProviderProfile, _ resolvedProfile) bool {
 	return providercatalog.NormalizeID(profile.CatalogID) == "chatgpt"
 }
 
+func sessionHeaderForProfile(profile config.ProviderProfile, resolved resolvedProfile) string {
+	switch providercatalog.NormalizeID(profile.CatalogID) {
+	case "opencode", "opencode-go", "opencode-go-anthropic-compatible":
+		return "x-opencode-session"
+	}
+	endpoint, err := url.Parse(resolved.baseURL)
+	if err == nil && strings.EqualFold(endpoint.Hostname(), "opencode.ai") && (endpoint.Path == "/zen" || strings.HasPrefix(endpoint.Path, "/zen/")) {
+		return "x-opencode-session"
+	}
+	return ""
+}
+
 // newCodexProvider builds a Codex-flavored openai provider for the chatgpt
 // catalog. The Codex headers (`originator`, `chatgpt-account-id`) are
 // injected by the CodexProvider wrapper. The `chatgpt-account-id` is read from

internal/providers/factory_test.go

@@ -3,13 +3,17 @@ package providers
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 	"io"
 	"net/http"
 	"strings"
+	"sync"
+	"sync/atomic"
 	"testing"
 
 	"github.com/Gitlawb/zero/internal/config"
 	"github.com/Gitlawb/zero/internal/oauth"
+	"github.com/Gitlawb/zero/internal/providers/providerio"
 	"github.com/Gitlawb/zero/internal/zeroruntime"
 )
 
@@ -794,3 +798,566 @@ func TestResolveRuntimeMetadataRejectsModelOutsideProviderAllowlist(t *testing.T
 		t.Fatalf("error = %q, want it to name the rejected model", err.Error())
 	}
 }
+
+func TestOpenCodeSessionHeader(t *testing.T) {
+	const sessionHeader = "x-opencode-session"
+	tests := []struct {
+		name       string
+		profile    config.ProviderProfile
+		response   string
+		wantHeader bool
+		wantAuth   map[string]string
+	}{
+		{
+			name: "catalog opencode-go default URL",
+			profile: config.ProviderProfile{
+				Name:         "opencode-go",
+				CatalogID:    "opencode-go",
+				ProviderKind: config.ProviderKindOpenAICompatible,
+				APIKey:       "sk-oc-go",
+				Model:        "deepseek-v4-pro",
+			},
+			response:   "data: [DONE]\n\n",
+			wantHeader: true,
+			wantAuth:   map[string]string{"Authorization": "Bearer sk-oc-go"},
+		},
+		{
+			name: "catalog opencode-go-anthropic-compatible",
+			profile: config.ProviderProfile{
+				Name:         "opencode-go-anthropic",
+				CatalogID:    "opencode-go-anthropic-compatible",
+				ProviderKind: config.ProviderKindAnthropicCompat,
+				APIKey:       "sk-oc-ant",
+				Model:        "minimax-m3",
+			},
+			response:   "data: {\"type\":\"message_stop\"}\n\n",
+			wantHeader: true,
+			wantAuth:   map[string]string{"x-api-key": "sk-oc-ant"},
+		},
+		{
+			name: "catalog opencode Zen",
+			profile: config.ProviderProfile{
+				Name:         "opencode-zen",
+				CatalogID:    "opencode",
+				ProviderKind: config.ProviderKindOpenAICompatible,
+				APIKey:       "sk-zen",
+				Model:        "test-model",
+			},
+			response:   "data: [DONE]\n\n",
+			wantHeader: true,
+			wantAuth:   map[string]string{"Authorization": "Bearer sk-zen"},
+		},
+		{
+			name: "renamed catalog profile with custom proxy URL",
+			profile: config.ProviderProfile{
+				Name:         "my-opencode",
+				CatalogID:    "opencode-go",
+				ProviderKind: config.ProviderKindOpenAICompatible,
+				BaseURL:      "https://proxy.example/v1",
+				APIKey:       "sk-proxy",
+				Model:        "test-model",
+			},
+			response:   "data: [DONE]\n\n",
+			wantHeader: true,
+			wantAuth:   map[string]string{"Authorization": "Bearer sk-proxy"},
+		},
+		{
+			name: "catalog-less OpenAI-compatible OpenCode Go URL",
+			profile: config.ProviderProfile{
+				Name:         "manual-go",
+				ProviderKind: config.ProviderKindOpenAICompatible,
+				BaseURL:      "https://opencode.ai/zen/go/v1",
+				APIKey:       "sk-manual",
+				Model:        "test-model",
+			},
+			response:   "data: [DONE]\n\n",
+			wantHeader: true,
+			wantAuth:   map[string]string{"Authorization": "Bearer sk-manual"},
+		},
+		{
+			name: "catalog-less Anthropic-compatible OpenCode Go URL",
+			profile: config.ProviderProfile{
+				Name:         "manual-go-anthropic",
+				ProviderKind: config.ProviderKindAnthropicCompat,
+				BaseURL:      "https://opencode.ai/zen/go",
+				APIKey:       "sk-manual-ant",
+				Model:        "test-model",
+			},
+			response:   "data: {\"type\":\"message_stop\"}\n\n",
+			wantHeader: true,
+			wantAuth:   map[string]string{"x-api-key": "sk-manual-ant"},
+		},
+		{
+			name: "official OpenAI",
+			profile: config.ProviderProfile{
+				Name:         "openai",
+				ProviderKind: config.ProviderKindOpenAI,
+				APIKey:       "sk-openai",
+				Model:        "test-model",
+			},
+			response:   "data: [DONE]\n\n",
+			wantHeader: false,
+			wantAuth:   map[string]string{"Authorization": "Bearer sk-openai"},
+		},
+		{
+			name: "generic OpenAI-compatible",
+			profile: config.ProviderProfile{
+				Name:         "generic",
+				ProviderKind: config.ProviderKindOpenAICompatible,
+				BaseURL:      "https://provider.example/v1",
+				APIKey:       "sk-generic",
+				Model:        "test-model",
+			},
+			response:   "data: [DONE]\n\n",
+			wantHeader: false,
+			wantAuth:   map[string]string{"Authorization": "Bearer sk-generic"},
+		},
+		{
+			name: "official Anthropic",
+			profile: config.ProviderProfile{
+				Name:         "anthropic",
+				ProviderKind: config.ProviderKindAnthropic,
+				APIKey:       "sk-ant",
+				Model:        "test-model",
+			},
+			response:   "data: {\"type\":\"message_stop\"}\n\n",
+			wantHeader: false,
+			wantAuth:   map[string]string{"x-api-key": "sk-ant"},
+		},
+		{
+			name: "lookalike subdomain is not OpenCode",
+			profile: config.ProviderProfile{
+				Name:         "deceptive-host",
+				ProviderKind: config.ProviderKindOpenAICompatible,
+				BaseURL:      "https://opencode.ai.example/zen/go/v1",
+				APIKey:       "sk-fake",
+				Model:        "test-model",
+			},
+			response:   "data: [DONE]\n\n",
+			wantHeader: false,
+			wantAuth:   map[string]string{"Authorization": "Bearer sk-fake"},
+		},
+		{
+			name: "lookalike path is not OpenCode",
+			profile: config.ProviderProfile{
+				Name:         "deceptive-path",
+				ProviderKind: config.ProviderKindOpenAICompatible,
+				BaseURL:      "https://example.com/opencode.ai/zen/go",
+				APIKey:       "sk-fake",
+				Model:        "test-model",
+			},
+			response:   "data: [DONE]\n\n",
+			wantHeader: false,
+			wantAuth:   map[string]string{"Authorization": "Bearer sk-fake"},
+		},
+		{
+			name: "zenith path is not Zen",
+			profile: config.ProviderProfile{
+				Name:         "zenith",
+				ProviderKind: config.ProviderKindOpenAICompatible,
+				BaseURL:      "https://opencode.ai/zenith",
+				APIKey:       "sk-zenith",
+				Model:        "test-model",
+			},
+			response:   "data: [DONE]\n\n",
+			wantHeader: false,
+			wantAuth:   map[string]string{"Authorization": "Bearer sk-zenith"},
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			transport := &captureTransport{responseBody: test.response}
+			provider, err := New(test.profile, Options{
+				HTTPClient: &http.Client{Transport: transport},
+				UserAgent:  "zero-test",
+			})
+			if err != nil {
+				t.Fatalf("New() error = %v", err)
+			}
+			stream, err := provider.StreamCompletion(context.Background(), zeroruntime.CompletionRequest{
+				Messages:       []zeroruntime.Message{{Role: zeroruntime.MessageRoleUser, Content: "hello"}},
+				PromptCacheKey: "conversation-a",
+			})
+			if err != nil {
+				t.Fatalf("StreamCompletion() error = %v", err)
+			}
+			drainStream(t, stream)
+			if transport.request == nil {
+				t.Fatal("HTTP client was not used")
+			}
+			got := transport.request.Header.Get(sessionHeader)
+			if test.wantHeader && got != "conversation-a" {
+				t.Fatalf("%s = %q, want %q", sessionHeader, got, "conversation-a")
+			}
+			if !test.wantHeader && got != "" {
+				t.Fatalf("%s = %q, want no session header", sessionHeader, got)
+			}
+			for header, want := range test.wantAuth {
+				if got := transport.request.Header.Get(header); got != want {
+					t.Fatalf("%s = %q, want %q", header, got, want)
+				}
+			}
+			if got := transport.request.Header.Get("User-Agent"); got != "zero-test" {
+				t.Fatalf("User-Agent = %q, want zero-test", got)
+			}
+			if test.profile.ProviderKind == config.ProviderKindOpenAICompatible {
+				var body map[string]any
+				if err := json.NewDecoder(transport.body()).Decode(&body); err != nil {
+					t.Fatalf("decode request body: %v", err)
+				}
+				if _, ok := body["prompt_cache_key"]; ok {
+					t.Fatalf("openai-compatible body carried prompt_cache_key: %#v", body["prompt_cache_key"])
+				}
+			}
+		})
+	}
+}
+
+func TestOpenCodeSessionHeaderFollowsConversationKey(t *testing.T) {
+	transport := &recordingTransport{status: http.StatusOK, body: "data: [DONE]\n\n"}
+	profile := config.ProviderProfile{
+		Name:         "opencode-go",
+		CatalogID:    "opencode-go",
+		ProviderKind: config.ProviderKindOpenAICompatible,
+		APIKey:       "sk-oc",
+		Model:        "test-model",
+	}
+	options := Options{HTTPClient: &http.Client{Transport: transport}, UserAgent: "zero-test"}
+	provider, err := New(profile, options)
+	if err != nil {
+		t.Fatalf("New() error = %v", err)
+	}
+	for _, key := range []string{"conversation-a", "conversation-a", "conversation-b"} {
+		stream, err := provider.StreamCompletion(context.Background(), zeroruntime.CompletionRequest{
+			Messages:       []zeroruntime.Message{{Role: zeroruntime.MessageRoleUser, Content: "hello"}},
+			PromptCacheKey: key,
+		})
+		if err != nil {
+			t.Fatalf("StreamCompletion() error = %v", err)
+		}
+		drainStream(t, stream)
+	}
+	got := transport.sessionHeaders()
+	want := []string{"conversation-a", "conversation-a", "conversation-b"}
+	if len(got) != len(want) {
+		t.Fatalf("captured %d requests, want %d", len(got), len(want))
+	}
+	for i := range want {
+		if got[i] != want[i] {
+			t.Fatalf("request %d x-opencode-session = %q, want %q", i, got[i], want[i])
+		}
+	}
+
+	reconstructed, err := New(profile, options)
+	if err != nil {
+		t.Fatalf("New() error = %v", err)
+	}
+	stream, err := reconstructed.StreamCompletion(context.Background(), zeroruntime.CompletionRequest{
+		Messages:       []zeroruntime.Message{{Role: zeroruntime.MessageRoleUser, Content: "hello"}},
+		PromptCacheKey: "conversation-a",
+	})
+	if err != nil {
+		t.Fatalf("StreamCompletion() error = %v", err)
+	}
+	drainStream(t, stream)
+	got = transport.sessionHeaders()
+	if last := got[len(got)-1]; last != "conversation-a" {
+		t.Fatalf("reconstructed provider sent %s = %q, want conversation-a", "x-opencode-session", last)
+	}
+}
+
+func TestOpenCodeSessionHeaderCustomOverride(t *testing.T) {
+	custom := map[string]string{"X-Opencode-Session": "explicit-session"}
+	profile := config.ProviderProfile{
+		Name:          "opencode-go",
+		CatalogID:     "opencode-go",
+		ProviderKind:  config.ProviderKindOpenAICompatible,
+		APIKey:        "sk-oc",
+		Model:         "test-model",
+		CustomHeaders: custom,
+	}
+	transport := &captureTransport{responseBody: "data: [DONE]\n\n"}
+	provider, err := New(profile, Options{HTTPClient: &http.Client{Transport: transport}, UserAgent: "zero-test"})
+	if err != nil {
+		t.Fatalf("New() error = %v", err)
+	}
+	stream, err := provider.StreamCompletion(context.Background(), zeroruntime.CompletionRequest{
+		Messages:       []zeroruntime.Message{{Role: zeroruntime.MessageRoleUser, Content: "hello"}},
+		PromptCacheKey: "conversation-a",
+	})
+	if err != nil {
+		t.Fatalf("StreamCompletion() error = %v", err)
+	}
+	drainStream(t, stream)
+	if got := transport.request.Header.Get("x-opencode-session"); got != "explicit-session" {
+		t.Fatalf("x-opencode-session = %q, want explicit custom value", got)
+	}
+	if len(custom) != 1 || custom["X-Opencode-Session"] != "explicit-session" {
+		t.Fatalf("profile CustomHeaders mutated: %#v", custom)
+	}
+}
+
+func TestOpenCodeSessionHeaderFallback(t *testing.T) {
+	transport := &recordingTransport{status: http.StatusOK, body: "data: [DONE]\n\n"}
+	profile := config.ProviderProfile{
+		Name:         "opencode-go",
+		CatalogID:    "opencode-go",
+		ProviderKind: config.ProviderKindOpenAICompatible,
+		APIKey:       "sk-oc",
+		Model:        "test-model",
+	}
+	options := Options{HTTPClient: &http.Client{Transport: transport}}
+	first, err := New(profile, options)
+	if err != nil {
+		t.Fatalf("New() error = %v", err)
+	}
+	second, err := New(profile, options)
+	if err != nil {
+		t.Fatalf("New() error = %v", err)
+	}
+	request := zeroruntime.CompletionRequest{
+		Messages: []zeroruntime.Message{{Role: zeroruntime.MessageRoleUser, Content: "hello"}},
+	}
+	for _, provider := range []zeroruntime.Provider{first, first, second} {
+		stream, err := provider.StreamCompletion(context.Background(), request)
+		if err != nil {
+			t.Fatalf("StreamCompletion() error = %v", err)
+		}
+		drainStream(t, stream)
+	}
+	headers := transport.sessionHeaders()
+	if len(headers) != 3 {
+		t.Fatalf("captured %d requests, want 3", len(headers))
+	}
+	if headers[0] == "" || headers[1] != headers[0] {
+		t.Fatalf("fallback headers = %q, %q — want one stable nonempty value per provider", headers[0], headers[1])
+	}
+	if headers[2] == headers[0] {
+		t.Fatalf("distinct provider instances shared fallback %q", headers[0])
+	}
+}
+
+func TestOpenCodeSessionHeaderDefaultsUserAgent(t *testing.T) {
+	transport := &captureTransport{responseBody: "data: [DONE]\n\n"}
+	provider, err := New(config.ProviderProfile{
+		Name:         "opencode-go",
+		CatalogID:    "opencode-go",
+		ProviderKind: config.ProviderKindOpenAICompatible,
+		APIKey:       "sk-oc",
+		Model:        "test-model",
+	}, Options{HTTPClient: &http.Client{Transport: transport}})
+	if err != nil {
+		t.Fatalf("New() error = %v", err)
+	}
+	stream, err := provider.StreamCompletion(context.Background(), zeroruntime.CompletionRequest{
+		Messages: []zeroruntime.Message{{Role: zeroruntime.MessageRoleUser, Content: "hello"}},
+	})
+	if err != nil {
+		t.Fatalf("StreamCompletion() error = %v", err)
+	}
+	drainStream(t, stream)
+	if got := transport.request.Header.Get("User-Agent"); got != "zero" {
+		t.Fatalf("User-Agent = %q, want zero", got)
+	}
+}
+
+func TestOpenCodeSessionHeaderConcurrent(t *testing.T) {
+	transport := &recordingTransport{status: http.StatusOK, body: "data: [DONE]\n\n"}
+	provider, err := New(config.ProviderProfile{
+		Name:         "opencode-go",
+		CatalogID:    "opencode-go",
+		ProviderKind: config.ProviderKindOpenAICompatible,
+		APIKey:       "sk-oc",
+		Model:        "test-model",
+	}, Options{HTTPClient: &http.Client{Transport: transport}})
+	if err != nil {
+		t.Fatalf("New() error = %v", err)
+	}
+
+	var wg sync.WaitGroup
+	var errsMu sync.Mutex
+	var errs []string
+	for _, session := range []string{"session-a", "session-b"} {
+		wg.Add(1)
+		go func(session string) {
+			defer wg.Done()
+			for i := 0; i < 5; i++ {
+				stream, err := provider.StreamCompletion(context.Background(), zeroruntime.CompletionRequest{
+					Messages:       []zeroruntime.Message{{Role: zeroruntime.MessageRoleUser, Content: fmt.Sprintf("req-%s-%d", session, i)}},
+					PromptCacheKey: session,
+				})
+				if err != nil {
+					errsMu.Lock()
+					errs = append(errs, err.Error())
+					errsMu.Unlock()
+					return
+				}
+				for event := range stream {
+					if event.Type == zeroruntime.StreamEventError {
+						errsMu.Lock()
+						errs = append(errs, event.Error)
+						errsMu.Unlock()
+					}
+				}
+			}
+		}(session)
+	}
+	wg.Wait()
+	for _, errText := range errs {
+		t.Errorf("concurrent stream error: %s", errText)
+	}
+
+	requests := transport.recorded()
+	if len(requests) != 10 {
+		t.Fatalf("captured %d requests, want 10", len(requests))
+	}
+	for _, request := range requests {
+		var payload struct {
+			Messages []struct {
+				Content string `json:"content"`
+			} `json:"messages"`
+		}
+		if err := json.Unmarshal([]byte(request.body), &payload); err != nil {
+			t.Fatalf("decode request body: %v", err)
+		}
+		if len(payload.Messages) == 0 {
+			t.Fatal("request carried no user message")
+		}
+		content := payload.Messages[0].Content
+		want := "session-a"
+		if strings.Contains(content, "session-b") {
+			want = "session-b"
+		}
+		if got := request.header.Get("x-opencode-session"); got != want {
+			t.Fatalf("request for %q carried x-opencode-session %q, want %q", content, got, want)
+		}
+	}
+}
+
+func TestOpenCodeSessionHeaderAuthRetry(t *testing.T) {
+	for _, test := range []struct {
+		name     string
+		profile  config.ProviderProfile
+		response string
+	}{
+		{
+			name: "openai-compatible",
+			profile: config.ProviderProfile{
+				Name:         "opencode-go",
+				CatalogID:    "opencode-go",
+				ProviderKind: config.ProviderKindOpenAICompatible,
+				APIKey:       "sk-oc",
+				Model:        "test-model",
+			},
+			response: "data: [DONE]\n\n",
+		},
+		{
+			name: "anthropic-compatible",
+			profile: config.ProviderProfile{
+				Name:         "opencode-go-anthropic",
+				CatalogID:    "opencode-go-anthropic-compatible",
+				ProviderKind: config.ProviderKindAnthropicCompat,
+				APIKey:       "sk-oc-ant",
+				Model:        "minimax-m3",
+			},
+			response: "data: {\"type\":\"message_stop\"}\n\n",
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			transport := &recordingTransport{status: http.StatusOK, body: test.response, unauthorized: 1}
+			var calls atomic.Int32
+			resolver := providerio.TokenResolver(func(context.Context, bool) (string, string, bool, error) {
+				n := calls.Add(1)
+				return "Authorization", fmt.Sprintf("Bearer tok-%d", n), true, nil
+			})
+			provider, err := New(test.profile, Options{
+				HTTPClient:    &http.Client{Transport: transport},
+				OAuthResolver: resolver,
+			})
+			if err != nil {
+				t.Fatalf("New() error = %v", err)
+			}
+			stream, err := provider.StreamCompletion(context.Background(), zeroruntime.CompletionRequest{
+				Messages:       []zeroruntime.Message{{Role: zeroruntime.MessageRoleUser, Content: "hello"}},
+				PromptCacheKey: "conversation-a",
+			})
+			if err != nil {
+				t.Fatalf("StreamCompletion() error = %v", err)
+			}
+			drainStream(t, stream)
+			requests := transport.recorded()
+			if len(requests) != 2 {
+				t.Fatalf("captured %d requests, want 2 (401 + retry)", len(requests))
+			}
+			for i, request := range requests {
+				if got := request.header.Get("x-opencode-session"); got != "conversation-a" {
+					t.Fatalf("attempt %d x-opencode-session = %q, want conversation-a", i, got)
+				}
+			}
+			if first, second := requests[0].header.Get("Authorization"), requests[1].header.Get("Authorization"); first == second {
+				t.Fatalf("Authorization not refreshed across retry: %q", first)
+			}
+		})
+	}
+}
+
+func drainStream(t *testing.T, stream <-chan zeroruntime.StreamEvent) {
+	t.Helper()
+	for event := range stream {
+		if event.Type == zeroruntime.StreamEventError {
+			t.Fatalf("stream error: %s", event.Error)
+		}
+	}
+}
+
+type recordedRequest struct {
+	header http.Header
+	body   string
+}
+
+type recordingTransport struct {
+	mu           sync.Mutex
+	requests     []recordedRequest
+	status       int
+	body         string
+	unauthorized int
+}
+
+func (transport *recordingTransport) RoundTrip(request *http.Request) (*http.Response, error) {
+	var body string
+	if request.Body != nil {
+		data, _ := io.ReadAll(request.Body)
+		body = string(data)
+	}
+	transport.mu.Lock()
+	transport.requests = append(transport.requests, recordedRequest{header: request.Header.Clone(), body: body})
+	attempt := len(transport.requests)
+	transport.mu.Unlock()
+
+	status := transport.status
+	if attempt <= transport.unauthorized {
+		status = http.StatusUnauthorized
+	}
+	return &http.Response{
+		StatusCode: status,
+		Status:     fmt.Sprintf("%d", status),
+		Header:     make(http.Header),
+		Body:       io.NopCloser(strings.NewReader(transport.body)),
+		Request:    request,
+	}, nil
+}
+
+func (transport *recordingTransport) recorded() []recordedRequest {
+	transport.mu.Lock()
+	defer transport.mu.Unlock()
+	return append([]recordedRequest(nil), transport.requests...)
+}
+
+func (transport *recordingTransport) sessionHeaders() []string {
+	requests := transport.recorded()
+	headers := make([]string, 0, len(requests))
+	for _, request := range requests {
+		headers = append(headers, request.header.Get("x-opencode-session"))
+	}
+	return headers
+}

internal/providers/openai/provider.go

@@ -65,6 +65,7 @@ type Options struct {
 	// enabled; the ZERO_DISABLE_PROMPT_CACHE_KEY env kill switch still applies
 	// on top for any endpoint.
 	DisablePromptCacheKey bool
+	SessionHeader         string
 }
 
 // Provider streams completions from an OpenAI-compatible chat completions API.
@@ -85,6 +86,7 @@ type Provider struct {
 	parseThinkTags        bool
 	setRequestExtra       func(*http.Request)
 	disablePromptCacheKey bool
+	sessionHeader         providerio.SessionHeader
 }
 
 // New creates an OpenAI-compatible provider.
@@ -140,6 +142,7 @@ func New(options Options) (*Provider, error) {
 		parseThinkTags:        options.ParseThinkTags,
 		setRequestExtra:       options.SetRequestExtra,
 		disablePromptCacheKey: options.DisablePromptCacheKey,
+		sessionHeader:         providerio.NewSessionHeader(options.SessionHeader),
 	}, nil
 }
 
@@ -156,13 +159,13 @@ func (provider *Provider) StreamCompletion(
 	events := make(chan zeroruntime.StreamEvent, 16)
 	go func() {
 		defer close(events)
-		provider.stream(ctx, body, events)
+		provider.stream(ctx, body, request.PromptCacheKey, events)
 	}()
 
 	return events, nil
 }
 
-func (provider *Provider) stream(ctx context.Context, body []byte, events chan<- zeroruntime.StreamEvent) {
+func (provider *Provider) stream(ctx context.Context, body []byte, sessionID string, events chan<- zeroruntime.StreamEvent) {
 	endpoint := provider.endpoint
 
 	// streamCtx lets the idle watchdog abort an in-flight body read by cancelling
@@ -186,6 +189,7 @@ func (provider *Provider) stream(ctx context.Context, body []byte, events chan<-
 		},
 		provider.oauthResolver,
 		func(request *http.Request) {
+			provider.sessionHeader.Apply(request, sessionID)
 			request.Header.Set("Content-Type", "application/json")
 			if provider.userAgent != "" {
 				request.Header.Set("User-Agent", provider.userAgent)

internal/providers/providerio/headers.go

@@ -1,6 +1,7 @@
 package providerio
 
 import (
+	"crypto/rand"
 	"net/http"
 	"strings"
 )
@@ -52,6 +53,28 @@ func ApplyAuthHeaders(request *http.Request, options AuthHeaders) {
 	request.Header.Set(header, value)
 }
 
+type SessionHeader struct {
+	name     string
+	fallback string
+}
+
+func NewSessionHeader(name string) SessionHeader {
+	if name == "" {
+		return SessionHeader{}
+	}
+	return SessionHeader{name: name, fallback: rand.Text()}
+}
+
+func (header SessionHeader) Apply(request *http.Request, sessionID string) {
+	if header.name == "" {
+		return
+	}
+	if sessionID = strings.TrimSpace(sessionID); sessionID == "" {
+		sessionID = header.fallback
+	}
+	request.Header.Set(header.name, sessionID)
+}
+
 func CopyHeaders(headers map[string]string) map[string]string {
 	if headers == nil {
 		return nil

internal/search/search.go

@@ -246,20 +246,62 @@ func RedactResult(result Result) Result {
 	return redacted
 }
 
+// redactMetadata redacts EVERY text field of the metadata, not the subset a
+// reader happens to think is user-facing. `zero search --json` prints this
+// straight to stdout, and the fields carrying the most free text are the ones
+// least likely to be on a hand-kept list: SpecUserComment and SpecRejectReason
+// are review text the user typed, SpecDraftReasoning is the model's own prose,
+// and Goal.Objective and Goal.StatusReason are whatever the goal was phrased
+// as. A field added to sessions.Metadata later is covered by
+// TestRedactMetadataCoversEveryTextField, which walks the struct rather than
+// repeating this list, so the two cannot drift apart silently.
 func redactMetadata(session sessions.Metadata, options redaction.Options) sessions.Metadata {
 	session.SessionID = redaction.RedactString(session.SessionID, options)
+	session.SessionKind = sessions.SessionKind(redaction.RedactString(string(session.SessionKind), options))
 	session.Title = redaction.RedactString(session.Title, options)
 	session.Cwd = redaction.RedactString(session.Cwd, options)
 	session.ModelID = redaction.RedactString(session.ModelID, options)
 	session.Provider = redaction.RedactString(session.Provider, options)
+	session.Tag = redaction.RedactString(session.Tag, options)
 	session.ParentSessionID = redaction.RedactString(session.ParentSessionID, options)
+	session.RootSessionID = redaction.RedactString(session.RootSessionID, options)
+	session.AgentName = redaction.RedactString(session.AgentName, options)
+	session.TaskID = redaction.RedactString(session.TaskID, options)
 	session.ForkedFromEventID = redaction.RedactString(session.ForkedFromEventID, options)
+	session.SpawnedFromEventID = redaction.RedactString(session.SpawnedFromEventID, options)
+	session.SpecID = redaction.RedactString(session.SpecID, options)
+	session.SpecFilePath = redaction.RedactString(session.SpecFilePath, options)
+	session.SpecStatus = sessions.SpecStatus(redaction.RedactString(string(session.SpecStatus), options))
+	session.SpecDraftModelID = redaction.RedactString(session.SpecDraftModelID, options)
+	session.SpecDraftReasoning = redaction.RedactString(session.SpecDraftReasoning, options)
+	session.SpecUserComment = redaction.RedactString(session.SpecUserComment, options)
+	session.SpecRejectReason = redaction.RedactString(session.SpecRejectReason, options)
+	session.SpecSourceSessionID = redaction.RedactString(session.SpecSourceSessionID, options)
+	session.SpecImplSessionID = redaction.RedactString(session.SpecImplSessionID, options)
 	session.CreatedAt = redaction.RedactString(session.CreatedAt, options)
 	session.UpdatedAt = redaction.RedactString(session.UpdatedAt, options)
 	session.LastEventType = sessions.EventType(redaction.RedactString(string(session.LastEventType), options))
+	session.Goal = redactGoal(session.Goal, options)
 	return session
 }
 
+// redactGoal returns a redacted COPY. Metadata is passed by value, but Goal is
+// a pointer inside it, so redacting through it would rewrite the goal the
+// caller still holds: a search would quietly edit the live session record it
+// was only supposed to report on.
+func redactGoal(goal *sessions.Goal, options redaction.Options) *sessions.Goal {
+	if goal == nil {
+		return nil
+	}
+	redacted := *goal
+	redacted.Objective = redaction.RedactString(redacted.Objective, options)
+	redacted.Status = sessions.GoalStatus(redaction.RedactString(string(redacted.Status), options))
+	redacted.StatusReason = redaction.RedactString(redacted.StatusReason, options)
+	redacted.CreatedAt = redaction.RedactString(redacted.CreatedAt, options)
+	redacted.UpdatedAt = redaction.RedactString(redacted.UpdatedAt, options)
+	return &redacted
+}
+
 func redactEventSummary(event EventSummary, options redaction.Options) EventSummary {
 	event.ID = redaction.RedactString(event.ID, options)
 	event.Type = sessions.EventType(redaction.RedactString(string(event.Type), options))

internal/search/search_test.go

@@ -1,12 +1,15 @@
 package search
 
 import (
+	"fmt"
 	"os"
 	"path/filepath"
+	"reflect"
 	"strings"
 	"testing"
 	"time"
 
+	"github.com/Gitlawb/zero/internal/redaction"
 	"github.com/Gitlawb/zero/internal/sessions"
 )
 
@@ -107,3 +110,156 @@ func fixedSearchClock(value string) func() time.Time {
 	}
 	return func() time.Time { return parsed }
 }
+
+// EVERY TEXT FIELD, NOT A HAND-KEPT SUBSET.
+//
+// `zero search --json` prints Hit.Session straight to stdout, so a field
+// redactMetadata forgets is a field that reaches the terminal with whatever was
+// in it. The list in redactMetadata is written out by hand; this walks the
+// struct instead, so a string field added to sessions.Metadata (or to the Goal
+// hanging off it) fails here on the day it lands rather than the day someone
+// notices it in output. It named twenty uncovered fields when it was written,
+// including the review text the user types and the model's own draft reasoning.
+func TestRedactMetadataCoversEveryTextField(t *testing.T) {
+	const secret = "sk-ant-api03-aaaaaaaaaaaaaaaaaaaaaaaa0123456789ABCD"
+
+	// The premise: the secret is one RedactString already recognizes, so a field
+	// that still carries it was not passed through the redactor at all.
+	if redaction.RedactString(secret, redaction.Options{}) == secret {
+		t.Fatalf("SETUP INVALID: %q is not a shape RedactString redacts, so every leg below passes vacuously", secret)
+	}
+
+	var session sessions.Metadata
+	filled := fillMetadataText(t, reflect.ValueOf(&session).Elem(), secret, 0)
+
+	var leaked []string
+	var checked int
+	walkMetadataText(t, reflect.ValueOf(redactMetadata(session, redaction.Options{})), "", 0, func(name, value string) {
+		checked++
+		if strings.Contains(value, secret) {
+			leaked = append(leaked, name)
+		}
+	})
+
+	// Filling and walking are separate traversals of the same shape, so a field
+	// one of them understands and the other does not would otherwise show up as
+	// a quiet pass rather than a failure.
+	if checked != filled {
+		t.Fatalf("SETUP INVALID: filled %d text fields and walked %d, so the two traversals disagree about the shape of Metadata", filled, checked)
+	}
+	if filled == 0 {
+		t.Fatal("SETUP INVALID: no text fields were populated, so this proves nothing")
+	}
+	if len(leaked) > 0 {
+		t.Errorf("redactMetadata left the secret in %d of %d text fields: %s",
+			len(leaked), checked, strings.Join(leaked, ", "))
+	}
+}
+
+// fillMetadataText writes text into every text-bearing field reachable from
+// value, allocating nil pointers and one-element slices on the way, and returns
+// how many strings it set.
+//
+// Recursive on purpose. The first version of this walked only the direct string
+// fields of one struct and hand-allocated the Goal next to it, which left the
+// guard with the same blind spot it exists to close: a nested struct added to
+// sessions.Metadata later would arrive empty, the walk would find nothing in it
+// and the test would pass while the new field went unredacted. Raised by
+// CodeRabbit on the PR.
+//
+// It fails rather than skips on a kind it does not understand, because a field
+// this cannot populate is a field the guard is not guarding.
+func fillMetadataText(t *testing.T, value reflect.Value, text string, depth int) int {
+	t.Helper()
+	if depth > 6 {
+		t.Fatalf("fillMetadataText recursed past depth %d, which suggests a cycle in the type", depth)
+	}
+	if !value.CanSet() {
+		return 0
+	}
+	switch value.Kind() {
+	case reflect.String:
+		value.SetString(text)
+		return 1
+	case reflect.Pointer:
+		if value.IsNil() {
+			value.Set(reflect.New(value.Type().Elem()))
+		}
+		return fillMetadataText(t, value.Elem(), text, depth+1)
+	case reflect.Struct:
+		filled := 0
+		for index := 0; index < value.NumField(); index++ {
+			if !value.Type().Field(index).IsExported() {
+				continue
+			}
+			filled += fillMetadataText(t, value.Field(index), text, depth+1)
+		}
+		return filled
+	case reflect.Slice:
+		value.Set(reflect.MakeSlice(value.Type(), 1, 1))
+		return fillMetadataText(t, value.Index(0), text, depth+1)
+	case reflect.Bool, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+		reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
+		reflect.Float32, reflect.Float64:
+		return 0
+	default:
+		t.Fatalf("fillMetadataText does not know how to populate %s (kind %s); teach it and walkMetadataText together, or this guard stops covering that field",
+			value.Type(), value.Kind())
+		return 0
+	}
+}
+
+// walkMetadataText visits every text-bearing field reachable from value, in the
+// same shape fillMetadataText populates. The two are deliberately symmetric and
+// the caller compares their counts.
+func walkMetadataText(t *testing.T, value reflect.Value, prefix string, depth int, visit func(name, value string)) {
+	t.Helper()
+	if depth > 6 {
+		t.Fatalf("walkMetadataText recursed past depth %d, which suggests a cycle in the type", depth)
+	}
+	switch value.Kind() {
+	case reflect.String:
+		visit(prefix, value.String())
+	case reflect.Pointer:
+		if !value.IsNil() {
+			walkMetadataText(t, value.Elem(), prefix, depth+1, visit)
+		}
+	case reflect.Struct:
+		for index := 0; index < value.NumField(); index++ {
+			field := value.Type().Field(index)
+			if !field.IsExported() {
+				continue
+			}
+			name := field.Name
+			if prefix != "" {
+				name = prefix + "." + name
+			}
+			walkMetadataText(t, value.Field(index), name, depth+1, visit)
+		}
+	case reflect.Slice:
+		for index := 0; index < value.Len(); index++ {
+			walkMetadataText(t, value.Index(index), fmt.Sprintf("%s[%d]", prefix, index), depth+1, visit)
+		}
+	}
+}
+
+// Metadata is passed by value, but Goal is a pointer inside it. Redacting
+// through that pointer would edit the session the caller still holds, so a
+// search would quietly rewrite the live record it was asked to report on.
+func TestRedactMetadataDoesNotRewriteTheCallersGoal(t *testing.T) {
+	const secret = "sk-ant-api03-aaaaaaaaaaaaaaaaaaaaaaaa0123456789ABCD"
+	goal := &sessions.Goal{Objective: "ship " + secret, StatusReason: "blocked on " + secret}
+	session := sessions.Metadata{SessionID: "s", Goal: goal}
+
+	redacted := redactMetadata(session, redaction.Options{})
+
+	if goal.Objective != "ship "+secret || goal.StatusReason != "blocked on "+secret {
+		t.Errorf("redactMetadata rewrote the caller's goal: %+v", *goal)
+	}
+	if redacted.Goal == goal {
+		t.Error("redacted metadata still points at the caller's goal")
+	}
+	if strings.Contains(redacted.Goal.Objective, secret) || strings.Contains(redacted.Goal.StatusReason, secret) {
+		t.Errorf("goal text was not redacted: %+v", *redacted.Goal)
+	}
+}