fix(ingestion): close the PR #152 review findings on REST auth

- main.go's wiring was untested (the test built its own copy of the
  router, so dropping auth in main or re-registering POST /query as
  public stayed green). Routing is now one function, buildMux, which
  main calls and the tests call: it constructs the bearer middleware
  itself, registers public handlers only for patterns on a fixed
  allowlist (a public REST pattern would beat the authenticated
  catch-all by specificity), refuses an empty token, and returns an
  http.Handler so nothing can add a route to the result.
- hyperguild CLI: PassRate sent no token and would 401. Every request
  now goes through brainClient.do, which adds it; the test covers
  Query, Write and PassRate and is named for that.
- ResolveIngestPath returns one refusal for every bad path; the raw
  EvalSymlinks error let a caller probe which server files exist and
  leaked the brain directory.
- PROJECT.md (and derived adapters) and the pass-rate runbook state
  that the REST API needs BRAIN_MCP_TOKEN and is tailnet/in-cluster.

Refs #149

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.context/PROJECT.md

@@ -64,7 +64,11 @@ the routing pod; brain tools moved to the brain MCP.
 
 The brain HTTP REST API (`/query`, `/write`, `/ingest`, `/ingest-raw`,
 `/ingest-path`, `/backfill-refs`, `/pass-rate`) remains available on port 3300
-for shell scripts and non-MCP clients.
+for shell scripts and non-MCP clients, **with the same bearer token as `/mcp`**
+(`BRAIN_MCP_TOKEN`; hyperguild#149). It is not served on the public host
+(infra#517): use the tailnet (`koala:8443`) or in-cluster
+`ingestion.supervisor.svc:3300`. `/ingest-path` and `brain_ingest` `path`
+accept only paths inside `brain/raw/`.
 
 `brain_answer(query)` performs BM25 retrieval + LLM synthesis (berget.ai
 gemma4:31b → iguana fallback). `brain_classify(text)` infers doc type, title,

.context/system-prompt.txt

@@ -304,7 +304,7 @@ entries that age well are about *why*, *how to avoid*, and *what to do when*.
 |---------|-------|-------|
 | **Claude Code, Claude Desktop** | `brain_query` (BM25), `brain_answer` (LLM-synth + sources) MCP tools | `brain_write` MCP tool |
 | **Crush, Pi, Antigravity, other MCP-capable** | same MCP server: `ingestion-brain` (via the `mcp__*_brain__*` namespace once authenticated) | same |
-| **Anything HTTP-only (curl, scripts)** | `POST https://brain-mcp.d-ma.be/query` with `{"query":"..."}` (auth via `BRAIN_MCP_TOKEN`) | `POST .../write` with `{"content":"...","filename":"..."}` |
+| **Anything HTTP-only (curl, scripts)** | Tailnet only: `POST https://koala.tail30472e.ts.net:8443/query` with `{"query":"..."}`, sending `BRAIN_MCP_TOKEN` (not yet enforced on REST, hyperguild#149). The public `brain-mcp.d-ma.be` serves `/mcp` only (infra#517). | `POST .../write` with `{"content":"...","wing":"...","hall":"..."}` |
 | **Browser / human inspection** | `https://git.d-ma.be/mathias/hyperguild` → `knowledge/` and `wiki/` markdown files |
 
 - **Scoping — the brain holds no confidential client content.** Nothing on the read path
@@ -493,7 +493,11 @@ the routing pod; brain tools moved to the brain MCP.
 
 The brain HTTP REST API (`/query`, `/write`, `/ingest`, `/ingest-raw`,
 `/ingest-path`, `/backfill-refs`, `/pass-rate`) remains available on port 3300
-for shell scripts and non-MCP clients.
+for shell scripts and non-MCP clients, **with the same bearer token as `/mcp`**
+(`BRAIN_MCP_TOKEN`; hyperguild#149). It is not served on the public host
+(infra#517): use the tailnet (`koala:8443`) or in-cluster
+`ingestion.supervisor.svc:3300`. `/ingest-path` and `brain_ingest` `path`
+accept only paths inside `brain/raw/`.
 
 `brain_answer(query)` performs BM25 retrieval + LLM synthesis (berget.ai
 gemma4:31b → iguana fallback). `brain_classify(text)` infers doc type, title,

AGENTS.md

@@ -299,7 +299,7 @@ entries that age well are about *why*, *how to avoid*, and *what to do when*.
 |---------|-------|-------|
 | **Claude Code, Claude Desktop** | `brain_query` (BM25), `brain_answer` (LLM-synth + sources) MCP tools | `brain_write` MCP tool |
 | **Crush, Pi, Antigravity, other MCP-capable** | same MCP server: `ingestion-brain` (via the `mcp__*_brain__*` namespace once authenticated) | same |
-| **Anything HTTP-only (curl, scripts)** | `POST https://brain-mcp.d-ma.be/query` with `{"query":"..."}` (auth via `BRAIN_MCP_TOKEN`) | `POST .../write` with `{"content":"...","filename":"..."}` |
+| **Anything HTTP-only (curl, scripts)** | Tailnet only: `POST https://koala.tail30472e.ts.net:8443/query` with `{"query":"..."}`, sending `BRAIN_MCP_TOKEN` (not yet enforced on REST, hyperguild#149). The public `brain-mcp.d-ma.be` serves `/mcp` only (infra#517). | `POST .../write` with `{"content":"...","wing":"...","hall":"..."}` |
 | **Browser / human inspection** | `https://git.d-ma.be/mathias/hyperguild` → `knowledge/` and `wiki/` markdown files |
 
 - **Scoping — the brain holds no confidential client content.** Nothing on the read path
@@ -488,7 +488,11 @@ the routing pod; brain tools moved to the brain MCP.
 
 The brain HTTP REST API (`/query`, `/write`, `/ingest`, `/ingest-raw`,
 `/ingest-path`, `/backfill-refs`, `/pass-rate`) remains available on port 3300
-for shell scripts and non-MCP clients.
+for shell scripts and non-MCP clients, **with the same bearer token as `/mcp`**
+(`BRAIN_MCP_TOKEN`; hyperguild#149). It is not served on the public host
+(infra#517): use the tailnet (`koala:8443`) or in-cluster
+`ingestion.supervisor.svc:3300`. `/ingest-path` and `brain_ingest` `path`
+accept only paths inside `brain/raw/`.
 
 `brain_answer(query)` performs BM25 retrieval + LLM synthesis (berget.ai
 gemma4:31b → iguana fallback). `brain_classify(text)` infers doc type, title,

CLAUDE.md

@@ -64,7 +64,11 @@ the routing pod; brain tools moved to the brain MCP.
 
 The brain HTTP REST API (`/query`, `/write`, `/ingest`, `/ingest-raw`,
 `/ingest-path`, `/backfill-refs`, `/pass-rate`) remains available on port 3300
-for shell scripts and non-MCP clients.
+for shell scripts and non-MCP clients, **with the same bearer token as `/mcp`**
+(`BRAIN_MCP_TOKEN`; hyperguild#149). It is not served on the public host
+(infra#517): use the tailnet (`koala:8443`) or in-cluster
+`ingestion.supervisor.svc:3300`. `/ingest-path` and `brain_ingest` `path`
+accept only paths inside `brain/raw/`.
 
 `brain_answer(query)` performs BM25 retrieval + LLM synthesis (berget.ai
 gemma4:31b → iguana fallback). `brain_classify(text)` infers doc type, title,

cmd/hyperguild/http.go

@@ -64,9 +64,7 @@ func (c *brainClient) Query(ctx context.Context, topic string, limit int) (*Quer
 		return nil, fmt.Errorf("build request: %w", err)
 	}
 	req.Header.Set("Content-Type", "application/json")
-	c.authorize(req)
-
-	resp, err := c.http.Do(req)
+	resp, err := c.do(req)
 	if err != nil {
 		return nil, fmt.Errorf("brain POST /query: %w", err)
 	}
@@ -108,9 +106,7 @@ func (c *brainClient) Write(ctx context.Context, wing, hall, filename string, co
 		return nil, fmt.Errorf("build request: %w", err)
 	}
 	req.Header.Set("Content-Type", "application/json")
-	c.authorize(req)
-
-	resp, err := c.http.Do(req)
+	resp, err := c.do(req)
 	if err != nil {
 		return nil, fmt.Errorf("brain POST /write: %w", err)
 	}
@@ -147,7 +143,7 @@ func (c *brainClient) PassRate(ctx context.Context, skill, window string) (*Pass
 	if err != nil {
 		return nil, fmt.Errorf("build request: %w", err)
 	}
-	resp, err := c.http.Do(req)
+	resp, err := c.do(req)
 	if err != nil {
 		return nil, fmt.Errorf("brain GET /pass-rate: %w", err)
 	}
@@ -163,9 +159,12 @@ func (c *brainClient) PassRate(ctx context.Context, skill, window string) (*Pass
 	return &out, nil
 }
 
-// authorize adds the bearer token when one is configured.
-func (c *brainClient) authorize(req *http.Request) {
+// do sends every brain request, adding the bearer token when one is
+// configured. All methods go through here so none can forget it (PassRate
+// did, PR #152 review).
+func (c *brainClient) do(req *http.Request) (*http.Response, error) {
 	if c.token != "" {
 		req.Header.Set("Authorization", "Bearer "+c.token)
 	}
+	return c.http.Do(req)
 }

cmd/hyperguild/http_auth_test.go

@@ -13,13 +13,17 @@ import (
 
 // hyperguild#149: the ingestion REST API now requires a bearer token; the CLI
 // sends BRAIN_MCP_TOKEN, or it gets 401 on every brain call.
-func TestBrainClientSendsBrainMCPToken(t *testing.T) {
+func TestBrainClientSendsBrainMCPTokenOnQueryWriteAndPassRate(t *testing.T) {
 	var got []string
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		got = append(got, r.URL.Path+" "+r.Header.Get("Authorization"))
-		if r.URL.Path == "/write" {
+		switch r.URL.Path {
+		case "/write":
 			_, _ = w.Write([]byte(`{"path":"wiki/x/facts/y.md"}`))
 			return
+		case "/pass-rate":
+			_, _ = w.Write([]byte(`{}`))
+			return
 		}
 		_, _ = w.Write([]byte(`{"results":[]}`))
 	}))
@@ -32,7 +36,10 @@ func TestBrainClientSendsBrainMCPToken(t *testing.T) {
 	require.NoError(t, err)
 	_, err = c.Write(context.Background(), "x", "facts", "y", strings.NewReader("# y"))
 	require.NoError(t, err)
-	assert.Equal(t, []string{"/query Bearer cli-test-token", "/write Bearer cli-test-token"}, got)
+	// PR #152 review: PassRate sent no token and would 401 in production.
+	_, _ = c.PassRate(context.Background(), "tdd", "7d")
+	assert.Equal(t, []string{"/query Bearer cli-test-token", "/write Bearer cli-test-token",
+		"/pass-rate Bearer cli-test-token"}, got)
 }
 
 func TestBrainClientSendsNoAuthorizationWhenTokenUnset(t *testing.T) {

docs/runbooks/exercising-pass-rate-traffic.md

@@ -24,7 +24,7 @@ Only a `tools/call` to the routing pod records a pass/fail.
 |---------|-----|------|
 | Routing MCP (local, Tailscale) | `http://koala:30310/mcp` | Bearer `ROUTING_MCP_TOKEN` |
 | Routing MCP (remote) | `https://routing-mcp.d-ma.be/mcp` | OAuth via `auth.d-ma.be` (audience `claude-ai`) |
-| Pass-rate readout | `http://koala:30330/pass-rate?skill=<name>` | none (read-only) |
+| Pass-rate readout | `http://koala:30330/pass-rate?skill=<name>` | Bearer `BRAIN_MCP_TOKEN` (since hyperguild#149) |
 
 Tools advertised: **`review`**, **`debug`** (the two the #35 gate measures),
 plus `session_log`, `retrospective`, `trainer`.

ingestion/cmd/server/main.go

@@ -503,9 +503,10 @@ func main() {
 		logger.Info("embed sync started", "interval_s", embedSyncInterval)
 	}
 
-	mux := http.NewServeMux()
+	// Public routes only; buildMux mounts the authenticated REST API (#149).
+	public := map[string]http.Handler{}
 	if webhookHandler != nil {
-		mux.Handle("POST /webhooks/brain-sync", webhookHandler)
+		public["POST /webhooks/brain-sync"] = webhookHandler
 	}
 	// Resource-metadata URL is only emitted on 401 when Dex OAuth is
 	// configured. Static-Bearer-only deployments leave this empty so
@@ -513,21 +514,14 @@ func main() {
 	var resourceMetadataURL string
 	if dexURL := os.Getenv("DEX_ISSUER_URL"); dexURL != "" {
 		resourceURL := os.Getenv("MCP_RESOURCE_URL")
-		mux.HandleFunc("GET /.well-known/oauth-protected-resource",
+		public["GET /.well-known/oauth-protected-resource"] = http.HandlerFunc(
 			chassisauth.ProtectedResourceHandler(resourceURL, dexURL))
 		if resourceURL != "" {
 			resourceMetadataURL = strings.TrimRight(resourceURL, "/") + "/.well-known/oauth-protected-resource"
 		}
 	}
 
-	mux.Handle("/mcp", chassisauth.BearerMiddleware(mcpToken, jwtValidator, "brain", resourceMetadataURL, mcpSrv))
-	// The REST API, authenticated as a whole (hyperguild#149). Same credential
-	// as /mcp: callers (brain-ui, brain-ingest-ntfy, the hyperguild CLI) send
-	// BRAIN_MCP_TOKEN. Registered after the public routes on purpose only for
-	// reading order; ServeMux precedence is by pattern specificity.
-	mountREST(mux, h, func(next http.Handler) http.Handler {
-		return chassisauth.BearerMiddleware(mcpToken, jwtValidator, "brain", resourceMetadataURL, next)
-	})
+	public["/mcp"] = chassisauth.BearerMiddleware(mcpToken, jwtValidator, "brain", resourceMetadataURL, mcpSrv)
 
 	// POST /capture (#53/#54): the uniform capture REST door. Needs a ticket
 	// tracker to file action items, so it only mounts when Gitea is
@@ -549,7 +543,7 @@ func main() {
 		sovereign := splitList(os.Getenv("BRAIN_CAPTURE_SOVEREIGN_PRINCIPALS"))
 		resolver := capturehttp.NewOriginResolver(sovereign)
 		captureH := capturehttp.New(captureSvc, jwtValidator, mcpToken, "local-cli", resolver)
-		mux.Handle("POST /capture", captureH)
+		public["POST /capture"] = captureH
 		// Same use-case behind the MCP `capture` tool (#55 relay) so MCP-native
 		// harnesses (claude.ai, Crush, Pi, LLM Council) reach capture through
 		// the existing /mcp OAuth connector. mcpSrv is already wrapped above;
@@ -579,9 +573,9 @@ func main() {
 			logger.Error("OAUTH_CLIENT_ID/SECRET set but MCP_RESOURCE_URL is empty; cannot derive issuer")
 			os.Exit(1)
 		}
-		mux.HandleFunc("GET /.well-known/oauth-authorization-server",
+		public["GET /.well-known/oauth-authorization-server"] = http.HandlerFunc(
 			oauth.MetadataHandler(issuer))
-		mux.HandleFunc("POST /oauth/token", oauth.TokenHandler(oauth.TokenConfig{
+		public["POST /oauth/token"] = http.HandlerFunc(oauth.TokenHandler(oauth.TokenConfig{
 			ClientID:     oauthID,
 			ClientSecret: oauthSecret,
 			AccessToken:  mcpToken,
@@ -600,7 +594,17 @@ func main() {
 	// real request latency. /metrics itself is excluded from its own
 	// observation by registering it on the outer mux (post-wrap).
 	reg := metrics.New()
-	mux.HandleFunc("GET /metrics", reg.Handler())
+	public["GET /metrics"] = http.HandlerFunc(reg.Handler())
+
+	// The whole router, built in one place so the test of buildMux is a test
+	// of production wiring (PR #152 review). The REST API's credential is the
+	// same as /mcp's.
+	mux, err := buildMux(restAuth{token: mcpToken, validator: jwtValidator, realm: "brain",
+		resourceMetadataURL: resourceMetadataURL}, h, public)
+	if err != nil {
+		logger.Error("build router", "err", err)
+		os.Exit(1)
+	}
 	logger.Info("metrics endpoint registered", "path", "/metrics")
 
 	addr := ":" + port

ingestion/cmd/server/routes.go

@@ -1,18 +1,65 @@
 package main
 
 import (
+	"errors"
+	"fmt"
 	"net/http"
 
+	chassisauth "git.d-ma.be/mathias/mcp-chassis/auth"
+
 	"github.com/mathiasbq/hyperguild/ingestion/internal/api"
 )
 
+// publicRoutes is the complete set of patterns allowed on the outer mux,
+// outside the REST API's auth (hyperguild#149). Each authenticates itself or is
+// meant to be open: /mcp (bearer/JWT), /capture (bearer/JWT), the webhook
+// (HMAC), /oauth/token (client secret), OAuth metadata and /metrics (open).
+// A REST pattern added here would beat the authenticated catch-all by
+// specificity and ship open, which is why buildMux refuses anything else.
+var publicRoutes = map[string]bool{
+	"/mcp":                      true,
+	"POST /capture":             true,
+	"POST /webhooks/brain-sync": true,
+	"GET /.well-known/oauth-protected-resource":   true,
+	"GET /.well-known/oauth-authorization-server": true,
+	"POST /oauth/token":                           true,
+	"GET /metrics":                                true,
+}
+
+// restAuth is the credential the REST API checks: the same as /mcp's.
+type restAuth struct {
+	token               string
+	validator           *chassisauth.JWTValidator
+	realm               string
+	resourceMetadataURL string
+}
+
+// buildMux is the server's whole router. The REST API is mounted at "/"
+// behind bearer auth that buildMux constructs itself, so a caller cannot pass
+// a no-op; public handlers are registered as given, and only for patterns on
+// the publicRoutes allowlist. It returns an http.Handler, not the
+// *ServeMux, so nothing can register a route on the result afterwards and
+// bypass the allowlist.
+func buildMux(auth restAuth, h *api.Handler, public map[string]http.Handler) (http.Handler, error) {
+	if auth.token == "" {
+		return nil, errors.New("buildMux: REST auth needs a token")
+	}
+	mux := http.NewServeMux()
+	for pattern, handler := range public {
+		if !publicRoutes[pattern] {
+			return nil, fmt.Errorf("buildMux: %q is not an allowed public route", pattern)
+		}
+		mux.Handle(pattern, handler)
+	}
+	mountREST(mux, h, func(next http.Handler) http.Handler {
+		return chassisauth.BearerMiddleware(auth.token, auth.validator, auth.realm, auth.resourceMetadataURL, next)
+	})
+	return mux, nil
+}
+
 // mountREST registers the REST API on its own mux and mounts it at "/" behind
-// auth (hyperguild#149). Authentication is a property of the mux, not of each
-// route: anything not registered on the outer mux as explicitly public (/mcp,
-// /capture, the HMAC webhook, OAuth metadata, /metrics) lands here and is
-// authenticated, including routes added later. Before this, only /mcp was
-// wrapped, and the REST routes beside it were open; infra#517 found them on
-// the internet.
+// auth: anything not registered as public lands here and is authenticated,
+// including routes added later.
 func mountREST(mux *http.ServeMux, h *api.Handler, auth func(http.Handler) http.Handler) {
 	rest := http.NewServeMux()
 	rest.HandleFunc("POST /query", h.Query)

ingestion/cmd/server/routes_test.go

@@ -9,8 +9,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
-
-	chassisauth "git.d-ma.be/mathias/mcp-chassis/auth"
+	"github.com/stretchr/testify/require"
 
 	"github.com/mathiasbq/hyperguild/ingestion/internal/api"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/pipeline"
@@ -18,22 +17,27 @@ import (
 
 const routesTok = "routes-test-token"
 
-// hyperguild#149: only /mcp was authenticated; every REST route on the same
-// mux was open, and infra#517 found them on the internet. The REST API is now
-// mounted at "/" behind the bearer middleware, so any route not registered
-// as explicitly public is authenticated, including routes added later.
-func testRouter(t *testing.T) http.Handler {
+func okHandler(body string) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) { _, _ = w.Write([]byte(body)) })
+}
+
+// testMux builds the router exactly as main does: buildMux with the full
+// public set main registers (stub handlers) and real bearer config.
+// hyperguild#149: the REST API is authenticated as a whole; the PR #152
+// review showed a test of a COPY of the router let main.go regress unseen.
+func testMux(t *testing.T) http.Handler {
 	t.Helper()
 	h := api.NewHandler(t.TempDir(), slog.New(slog.NewTextHandler(os.Stderr, nil)), pipeline.Config{})
-	mux := http.NewServeMux()
-	mux.HandleFunc("GET /metrics", func(w http.ResponseWriter, _ *http.Request) { _, _ = w.Write([]byte("ok")) })
-	mountREST(mux, h, func(next http.Handler) http.Handler {
-		return chassisauth.BearerMiddleware(routesTok, nil, "brain", "", next)
-	})
+	public := map[string]http.Handler{}
+	for p := range publicRoutes {
+		public[p] = okHandler("public " + p)
+	}
+	mux, err := buildMux(restAuth{token: routesTok, realm: "brain"}, h, public)
+	require.NoError(t, err)
 	return mux
 }
 
-func do(t *testing.T, h http.Handler, method, path, authz string) int {
+func do(t *testing.T, h http.Handler, method, path, authz string) (int, string) {
 	t.Helper()
 	req := httptest.NewRequest(method, path, strings.NewReader(`{"query":"x"}`))
 	if authz != "" {
@@ -41,34 +45,62 @@ func do(t *testing.T, h http.Handler, method, path, authz string) int {
 	}
 	rec := httptest.NewRecorder()
 	h.ServeHTTP(rec, req)
-	return rec.Code
+	return rec.Code, rec.Body.String()
 }
 
-func TestRESTRoutesRefuseRequestsWithoutAToken(t *testing.T) {
-	r := testRouter(t)
+func TestBuildMuxRefusesRESTRoutesWithoutAValidToken(t *testing.T) {
+	r := testMux(t)
 	for _, rt := range []struct{ method, path string }{
 		{"POST", "/query"}, {"POST", "/write"}, {"POST", "/index"}, {"POST", "/ingest"},
 		{"POST", "/ingest-path"}, {"POST", "/ingest-raw"}, {"POST", "/backfill-refs"},
 		{"GET", "/pending"}, {"POST", "/promote"}, {"POST", "/backfill-embeddings"}, {"GET", "/pass-rate"},
 	} {
-		assert.Equal(t, http.StatusUnauthorized, do(t, r, rt.method, rt.path, ""), "%s %s without a token", rt.method, rt.path)
-		assert.Equal(t, http.StatusUnauthorized, do(t, r, rt.method, rt.path, "Bearer wrong"), "%s %s with a wrong token", rt.method, rt.path)
+		code, _ := do(t, r, rt.method, rt.path, "")
+		assert.Equal(t, http.StatusUnauthorized, code, "%s %s without a token", rt.method, rt.path)
+		code, _ = do(t, r, rt.method, rt.path, "Bearer wrong")
+		assert.Equal(t, http.StatusUnauthorized, code, "%s %s with a wrong token", rt.method, rt.path)
 	}
 }
 
-func TestRESTRoutesServeAValidToken(t *testing.T) {
-	r := testRouter(t)
-	assert.NotEqual(t, http.StatusUnauthorized, do(t, r, "POST", "/query", "Bearer "+routesTok))
-	assert.Equal(t, http.StatusOK, do(t, r, "GET", "/pending", "Bearer "+routesTok))
+func TestBuildMuxServesRESTRoutesToAValidToken(t *testing.T) {
+	r := testMux(t)
+	code, _ := do(t, r, "GET", "/pending", "Bearer "+routesTok)
+	assert.Equal(t, http.StatusOK, code)
 }
 
-// Default-deny: a path nobody registered is still behind auth, so a route
-// added to the REST mux later cannot ship open by omission.
-func TestUnregisteredPathIsAuthenticatedByDefault(t *testing.T) {
-	assert.Equal(t, http.StatusUnauthorized, do(t, testRouter(t), "POST", "/some-future-route", ""))
+func TestBuildMuxAuthenticatesAnUnregisteredPath(t *testing.T) {
+	code, _ := do(t, testMux(t), "POST", "/some-future-route", "")
+	assert.Equal(t, http.StatusUnauthorized, code)
 }
 
-// Explicitly public routes registered on the outer mux keep working.
-func TestMetricsStaysOpenForPrometheus(t *testing.T) {
-	assert.Equal(t, http.StatusOK, do(t, testRouter(t), "GET", "/metrics", ""))
+// buildMux registers public handlers as given, without adding auth: each
+// public route owns its own (bearer on /mcp, HMAC on the webhook, client
+// secret on /oauth/token) or is meant to be open (/metrics, OAuth metadata).
+func TestBuildMuxDoesNotWrapPublicRoutes(t *testing.T) {
+	r := testMux(t)
+	for p := range publicRoutes {
+		method, path, ok := strings.Cut(p, " ")
+		if !ok {
+			method, path = "GET", p
+		}
+		code, body := do(t, r, method, path, "")
+		assert.Equal(t, http.StatusOK, code, p)
+		assert.Equal(t, "public "+p, body, p)
+	}
+}
+
+// The allowlist is the control: a REST pattern registered as public would win
+// over the authenticated catch-all (more specific pattern), so it is refused.
+func TestBuildMuxRefusesAPublicPatternOffTheAllowlist(t *testing.T) {
+	h := api.NewHandler(t.TempDir(), slog.New(slog.NewTextHandler(os.Stderr, nil)), pipeline.Config{})
+	for _, p := range []string{"POST /query", "GET /pending", "/", "POST /metrics"} {
+		_, err := buildMux(restAuth{token: routesTok, realm: "brain"}, h, map[string]http.Handler{p: okHandler("x")})
+		assert.Error(t, err, "public pattern %q must be refused", p)
+	}
+}
+
+func TestBuildMuxRefusesAnEmptyToken(t *testing.T) {
+	h := api.NewHandler(t.TempDir(), slog.New(slog.NewTextHandler(os.Stderr, nil)), pipeline.Config{})
+	_, err := buildMux(restAuth{token: "", realm: "brain"}, h, nil)
+	assert.Error(t, err)
 }

ingestion/internal/api/ingestpath_root.go

@@ -2,13 +2,14 @@ package api
 
 import (
 	"errors"
-	"fmt"
 	"path/filepath"
 	"strings"
 )
 
-// ErrOutsideIngestRoot means an ingest path does not resolve inside brain/raw/.
-var ErrOutsideIngestRoot = errors.New("ingest path must be inside brain/raw/")
+// ErrOutsideIngestRoot is the one refusal for every bad ingest path. It never
+// carries the underlying error: "no such file" versus "permission denied"
+// would let a caller probe which server files exist (PR #152 review).
+var ErrOutsideIngestRoot = errors.New("ingest path must be an existing file or directory inside brain/raw/")
 
 // ResolveIngestPath confines a caller-supplied ingest path to brain/raw/, the
 // inbox the watcher already owns (hyperguild#149). Relative paths resolve
@@ -16,18 +17,18 @@ var ErrOutsideIngestRoot = errors.New("ingest path must be inside brain/raw/")
 // a link inside raw/ that points elsewhere is refused. The path must exist.
 func ResolveIngestPath(brainDir, p string) (string, error) {
 	if strings.TrimSpace(p) == "" {
-		return "", fmt.Errorf("%w: path is empty", ErrOutsideIngestRoot)
+		return "", ErrOutsideIngestRoot
 	}
 	root, err := filepath.EvalSymlinks(filepath.Join(brainDir, "raw"))
 	if err != nil {
-		return "", fmt.Errorf("%w: inbox unavailable: %v", ErrOutsideIngestRoot, err)
+		return "", ErrOutsideIngestRoot
 	}
 	if !filepath.IsAbs(p) {
 		p = filepath.Join(root, p)
 	}
 	real, err := filepath.EvalSymlinks(filepath.Clean(p))
 	if err != nil {
-		return "", fmt.Errorf("%w: %v", ErrOutsideIngestRoot, err)
+		return "", ErrOutsideIngestRoot
 	}
 	rel, err := filepath.Rel(root, real)
 	if err != nil || rel == ".." || strings.HasPrefix(rel, ".."+string(filepath.Separator)) || filepath.IsAbs(rel) {

ingestion/internal/api/ingestpath_root_test.go

@@ -67,3 +67,22 @@ func TestIngestPathDirectoryWalkSkipsSymlinksLeavingTheInbox(t *testing.T) {
 	assert.Contains(t, rec.Body.String(), "skipped")
 	assert.NotContains(t, rec.Body.String(), "SENTINEL-149-OUTSIDE")
 }
+
+// PR #152 review: the raw EvalSymlinks error told an authenticated caller
+// whether any server file existed ("no such file") or was unreadable
+// ("permission denied"), and leaked the brain directory. Every refusal now
+// reads the same.
+func TestResolveIngestPathRefusalsAreIndistinguishable(t *testing.T) {
+	brain := t.TempDir()
+	require.NoError(t, os.MkdirAll(filepath.Join(brain, "raw"), 0o755))
+	var msgs []string
+	for _, p := range []string{"/etc/hostname", "/etc/definitely-not-here-149", "../x", "nope/missing.md", ""} {
+		_, err := api.ResolveIngestPath(brain, p)
+		require.Error(t, err, p)
+		msgs = append(msgs, err.Error())
+		assert.NotContains(t, err.Error(), brain, "refusal for %q leaks the brain dir", p)
+	}
+	for _, m := range msgs[1:] {
+		assert.Equal(t, msgs[0], m)
+	}
+}