fix(routing): repair pass-rate instrumentation (3 bugs) — #73, #35

The #35 data gate could never fill: a real review call routed cleanly to
qwen36 but /pass-rate stayed total:0 under every key. Root cause was three
independent defects in the session_log path, each alone fatal:

- A: a successful routed call logged final_status "skip", never "pass".
  /pass-rate computes pass/(pass+fail) and skips count as neither, so the
  >=0.90 gate was mathematically unreachable. Success now logs "pass".
- B: every record was written under skill "_routing", so /pass-rate?skill=
  review|debug (what #35 measures) always read zero. Now uses the real
  e.Skill; routing decisions stay groupable via session_id "_routing".
- C: the session_log POST to the bearer-gated ingestion /mcp carried no
  Authorization header → silent 401, swallowed by best-effort logging
  (the documented mcpclient-empty-token-silent-401 footgun). Logger now
  takes a token (BRAIN_MCP_TOKEN) and sets the bearer when non-empty.

Tests rewritten to assert correct behavior (they had encoded the bugs:
"skip" on success, "_routing" skill). New test covers the auth header and
the empty-token path.

Infra (BRAIN_MCP_TOKEN ExternalSecret + env on the routing deployment) and
redeploy follow separately. Refs #73, #35.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

cmd/routing/main.go

@@ -53,7 +53,7 @@ func main() {
 
 	router := &routing.Router{
 		Fetcher:       routing.NewFetcher(cfg.BrainURL, "7d", time.Duration(cfg.PassRateTTLSeconds)*time.Second),
-		Logger:        routing.NewLogger(cfg.BrainURL),
+		Logger:        routing.NewLogger(cfg.BrainURL, cfg.BrainMCPToken),
 		Policy:        routing.Policy{Floor: cfg.RouteLocalFloor, Ceil: cfg.RouteLocalCeil},
 		FastModel:     cfg.FastModel,
 		ThinkingModel: cfg.ThinkingModel,

internal/config/routing.go

@@ -14,6 +14,7 @@ type RoutingConfig struct {
 	LiteLLMBaseURL     string  // LITELLM_BASE_URL, default https://llm-api.d-ma.be
 	LiteLLMAPIKey      string  // LITELLM_API_KEY
 	BrainURL           string  // BRAIN_URL, default http://ingestion.supervisor:3300
+	BrainMCPToken      string  // BRAIN_MCP_TOKEN, bearer for the auth-gated ingestion /mcp (session_log)
 	FastModel          string  // HYPERGUILD_FAST_MODEL, default koala/qwen35-9b-fast
 	ThinkingModel      string  // HYPERGUILD_THINKING_MODEL, default iguana/gemma4-26b
 	// RouteLocalFloor and RouteLocalCeil intentionally invert the usual
@@ -44,6 +45,7 @@ func LoadRouting() (RoutingConfig, error) {
 		LiteLLMBaseURL: envOr("LITELLM_BASE_URL", "https://llm-api.d-ma.be"),
 		LiteLLMAPIKey:  os.Getenv("LITELLM_API_KEY"),
 		BrainURL:       envOr("BRAIN_URL", "http://ingestion.supervisor:3300"),
+		BrainMCPToken:  os.Getenv("BRAIN_MCP_TOKEN"),
 		FastModel:      envOr("HYPERGUILD_FAST_MODEL", "koala/qwen35-9b-fast"),
 		ThinkingModel:  envOr("HYPERGUILD_THINKING_MODEL", "iguana/gemma4-26b"),
 	}

internal/routing/log.go

@@ -17,19 +17,24 @@ type LogEntry struct {
 	Message     string // free-form, e.g. "model=qwen35, pass_rate=0.94"
 	ProjectRoot string
 	DurationMs  int64
-	Failed      bool // true → final_status: "fail"; false → "skip"
+	Failed      bool // true → final_status: "fail"; false → "pass"
 }
 
 // Logger posts session_log entries to a brain MCP at BrainURL + /mcp.
 type Logger struct {
 	BrainURL string
+	Token    string // bearer for the (auth-gated) ingestion /mcp; empty = no header
 	HTTP     *http.Client
 }
 
-// NewLogger creates a Logger with a 2-second HTTP timeout.
-func NewLogger(brainURL string) *Logger {
+// NewLogger creates a Logger with a 2-second HTTP timeout. token authenticates
+// to the bearer-gated ingestion /mcp; an empty token sends no Authorization
+// header (and silently 401s against a gated server — see brain
+// mcpclient-empty-token-silent-401-envfrom-missing-key).
+func NewLogger(brainURL, token string) *Logger {
 	return &Logger{
 		BrainURL: brainURL,
+		Token:    token,
 		HTTP:     &http.Client{Timeout: 2 * time.Second},
 	}
 }
@@ -37,7 +42,10 @@ func NewLogger(brainURL string) *Logger {
 // LogDecision posts a session_log MCP call. Errors are returned but the caller
 // MUST NOT block real work on them — logging is best-effort.
 func (l *Logger) LogDecision(ctx context.Context, e LogEntry) error {
-	status := "skip"
+	// A completed routed call is a pass (liveness); only an execution error is a
+	// fail. There is no "skip" for routing — the prior default-to-"skip" meant a
+	// successful call never counted toward pass_rate, so the gate was unreachable.
+	status := "pass"
 	if e.Failed {
 		status = "fail"
 	}
@@ -48,8 +56,10 @@ func (l *Logger) LogDecision(ctx context.Context, e LogEntry) error {
 		"params": map[string]any{
 			"name": "session_log",
 			"arguments": map[string]any{
-				"session_id":   e.SessionID,
-				"skill":        "_routing",
+				"session_id": e.SessionID,
+				// The real skill, so /pass-rate?skill=review|debug sees these
+				// records; routing decisions stay groupable via session_id "_routing".
+				"skill":        e.Skill,
 				"phase":        "decide",
 				"final_status": status,
 				"message":      fmt.Sprintf("%s: %s — %s", e.Skill, e.Decision, e.Message),
@@ -67,6 +77,9 @@ func (l *Logger) LogDecision(ctx context.Context, e LogEntry) error {
 		return fmt.Errorf("log: build request: %w", err)
 	}
 	req.Header.Set("Content-Type", "application/json")
+	if l.Token != "" {
+		req.Header.Set("Authorization", "Bearer "+l.Token)
+	}
 	resp, err := l.HTTP.Do(req)
 	if err != nil {
 		return fmt.Errorf("log: request: %w", err)

internal/routing/log_test.go

@@ -15,36 +15,44 @@ import (
 
 func TestLoggerLogDecision(t *testing.T) {
 	var captured map[string]any
+	var authHeader string
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		assert.Equal(t, http.MethodPost, r.Method)
 		assert.Equal(t, "/mcp", r.URL.Path)
+		authHeader = r.Header.Get("Authorization")
 		body, _ := io.ReadAll(r.Body)
 		require.NoError(t, json.Unmarshal(body, &captured))
 		_ = json.NewEncoder(w).Encode(map[string]any{"jsonrpc": "2.0", "id": 1, "result": map[string]any{"content": []map[string]any{{"type": "text", "text": "ok"}}}})
 	}))
 	defer srv.Close()
 
-	l := routing.NewLogger(srv.URL)
+	l := routing.NewLogger(srv.URL, "test-token")
 	err := l.LogDecision(context.Background(), routing.LogEntry{
 		SessionID:   "sess-1",
 		Skill:       "review",
 		Decision:    "local",
-		Message:     "model=qwen35, pass_rate=0.94",
+		Message:     "model=qwen36, pass_rate=0.94",
 		ProjectRoot: "/home/x/proj",
 		DurationMs:  1234,
 		Failed:      false,
 	})
 	require.NoError(t, err)
 
+	// Bug C fix: the POST authenticates to the bearer-gated ingestion /mcp.
+	assert.Equal(t, "Bearer test-token", authHeader)
+
 	params := captured["params"].(map[string]any)
 	assert.Equal(t, "tools/call", captured["method"])
 	assert.Equal(t, "session_log", params["name"])
 
 	args := params["arguments"].(map[string]any)
-	assert.Equal(t, "_routing", args["skill"])
+	// Bug B fix: the record carries the real skill so /pass-rate?skill=review sees it.
+	assert.Equal(t, "review", args["skill"])
 	assert.Equal(t, "decide", args["phase"])
-	assert.Equal(t, "skip", args["final_status"])
+	// Bug A fix: a successful routed call logs "pass", not "skip".
+	assert.Equal(t, "pass", args["final_status"])
 	assert.Contains(t, args["message"].(string), "review: local")
+	// session grouping is preserved via session_id.
 	assert.Equal(t, "sess-1", args["session_id"])
 	assert.Equal(t, "/home/x/proj", args["project_root"])
 	assert.Equal(t, float64(1234), args["duration_ms"])
@@ -59,23 +67,40 @@ func TestLoggerLogFailure(t *testing.T) {
 	}))
 	defer srv.Close()
 
-	l := routing.NewLogger(srv.URL)
+	l := routing.NewLogger(srv.URL, "test-token")
 	err := l.LogDecision(context.Background(), routing.LogEntry{
 		SessionID: "s", Skill: "debug", Decision: "local", Message: "litellm down", Failed: true,
 	})
 	require.NoError(t, err)
 
 	args := captured["params"].(map[string]any)["arguments"].(map[string]any)
+	assert.Equal(t, "debug", args["skill"])
 	assert.Equal(t, "fail", args["final_status"])
 }
 
+func TestLoggerOmitsAuthWhenTokenEmpty(t *testing.T) {
+	var authHeader string
+	hasAuth := false
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		authHeader = r.Header.Get("Authorization")
+		_, hasAuth = r.Header["Authorization"]
+		_ = json.NewEncoder(w).Encode(map[string]any{"jsonrpc": "2.0", "id": 1, "result": map[string]any{}})
+	}))
+	defer srv.Close()
+
+	l := routing.NewLogger(srv.URL, "")
+	require.NoError(t, l.LogDecision(context.Background(), routing.LogEntry{Skill: "review", SessionID: "_routing", Decision: "local"}))
+	assert.False(t, hasAuth, "no Authorization header should be set when token is empty")
+	assert.Equal(t, "", authHeader)
+}
+
 func TestLoggerSurfacesUpstreamError(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
 		http.Error(w, "down", http.StatusBadGateway)
 	}))
 	defer srv.Close()
 
-	l := routing.NewLogger(srv.URL)
+	l := routing.NewLogger(srv.URL, "test-token")
 	err := l.LogDecision(context.Background(), routing.LogEntry{Skill: "x", SessionID: "y", Decision: "local"})
 	require.Error(t, err)
 }

internal/routing/router_test.go

@@ -50,7 +50,7 @@ func newRouter(t *testing.T, llm *fakeLLM, passRate float64) (*routing.Router, *
 
 	r := &routing.Router{
 		Fetcher:       routing.NewFetcher(brain.URL, "7d", time.Minute),
-		Logger:        routing.NewLogger(brain.URL),
+		Logger:        routing.NewLogger(brain.URL, ""),
 		Policy:        routing.Policy{Floor: 0.9, Ceil: 0.7},
 		FastModel:     "koala/qwen35-9b-fast",
 		ThinkingModel: "iguana/gemma4-26b",
@@ -117,7 +117,7 @@ func TestRouterDefaultsToFastWhenBrainUnreachable(t *testing.T) {
 	llm := &fakeLLM{resp: "ok"}
 	r := &routing.Router{
 		Fetcher:       routing.NewFetcher(brain.URL, "7d", time.Minute),
-		Logger:        routing.NewLogger(brain.URL),
+		Logger:        routing.NewLogger(brain.URL, ""),
 		Policy:        routing.Policy{Floor: 0.9, Ceil: 0.7},
 		FastModel:     "koala/qwen35-9b-fast",
 		ThinkingModel: "iguana/gemma4-26b",