feat(ingestion): migrate to gitea.d-ma.be/mathias/mcp-chassis v0.1.0

Second port of the MCP chassis (gitea-mcp was first, commit 658f4ba).
Closes the chassis-adoption loop on the two highest-LOC consumers.

Changes:
- Drop ingestion/internal/auth/ entirely (jwt.go + jwt_test.go +
  protected_resource.go + protected_resource_test.go) — chassis provides
  JWTValidator + ProtectedResourceHandler with identical semantics.
- Drop ingestion/internal/mcp/auth.go (BearerAuth function, ~65 LOC)
  and the integration test auth_test.go (~200 LOC) — chassis
  BearerMiddleware replaces it. Static-Bearer-or-Dex-JWT precedence and
  RFC 9728 resource_metadata challenge behavior preserved 1:1.
- cmd/server/main.go: import chassis as `chassisauth`, rewire the three
  call sites. Use realm="brain" in the BearerMiddleware call so a 401
  challenge identifies the resource as the brain MCP.

OAuth client_credentials handler (ingestion/internal/oauth) stays —
chassis v0.1.0 covers only the JWT path; OAuth flow is a candidate for
chassis v0.2.0 once a second MCP needs it (rule of three).

Net delta: -~330 LOC of duplicated auth code; +1 import; +1 GOPRIVATE
env requirement on dev machines (documented in the spike handoff
2026-05-22-mcp-chassis-spike.md).

task check green (lint + test + vet + govulncheck).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ingestion/internal/mcp/auth.go

@@ -1,65 +0,0 @@
-package mcp
-
-import (
-	"crypto/subtle"
-	"net/http"
-	"strings"
-
-	"github.com/mathiasbq/hyperguild/ingestion/internal/auth"
-)
-
-// BearerAuth gates an HTTP handler behind dual-mode authentication.
-//
-// Auth precedence:
-//
-//  1. Static Bearer match (constant-time compare against staticToken).
-//     Wins immediately and never emits a WWW-Authenticate header. This is
-//     the path used by internal Tailscale/LAN CLI callers that supply
-//     `Authorization: Bearer $BRAIN_MCP_TOKEN` via `.mcp.json`. Returning
-//     200 without a WWW-Authenticate prevents the MCP client from
-//     speculatively flipping into OAuth-discovery mode.
-//  2. Dex JWT validation (when validator is non-nil). Used by claude.ai
-//     custom MCP connectors that finished the OAuth handshake.
-//  3. Otherwise 401. When resourceMetadataURL is non-empty, a
-//     `WWW-Authenticate: Bearer resource_metadata="…"` header is emitted
-//     per RFC 9728 §6.2 so claude.ai's OAuth discovery flow can find the
-//     server's protected-resource metadata document.
-//
-// The order matters: a valid static Bearer must short-circuit BEFORE any
-// JWT path runs, because a non-empty WWW-Authenticate emitted on the
-// fall-through 401 confuses static-Bearer-only clients into discarding
-// their header and starting an OAuth handshake instead.
-func BearerAuth(staticToken string, validator *auth.Validator, resourceMetadataURL string, next http.Handler) http.Handler {
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		rawToken, ok := strings.CutPrefix(r.Header.Get("Authorization"), "Bearer ")
-		if !ok {
-			unauthorized(w, resourceMetadataURL)
-			return
-		}
-
-		// 1. Static Bearer wins first — never emits a challenge.
-		if staticToken != "" && subtle.ConstantTimeCompare([]byte(rawToken), []byte(staticToken)) == 1 {
-			next.ServeHTTP(w, r)
-			return
-		}
-
-		// 2. Then Dex JWT, if configured.
-		if validator != nil {
-			if _, err := validator.Validate(r.Context(), rawToken); err == nil {
-				next.ServeHTTP(w, r)
-				return
-			}
-		}
-
-		// 3. Reject with an OAuth resource-metadata challenge if configured.
-		unauthorized(w, resourceMetadataURL)
-	})
-}
-
-func unauthorized(w http.ResponseWriter, resourceMetadataURL string) {
-	if resourceMetadataURL != "" {
-		w.Header().Set("WWW-Authenticate",
-			`Bearer realm="brain", resource_metadata="`+resourceMetadataURL+`"`)
-	}
-	http.Error(w, "unauthorized", http.StatusUnauthorized)
-}

ingestion/internal/mcp/auth_test.go

@@ -1,202 +0,0 @@
-package mcp_test
-
-import (
-	"context"
-	"crypto/rand"
-	"crypto/rsa"
-	"encoding/json"
-	"net/http"
-	"net/http/httptest"
-	"testing"
-	"time"
-
-	"github.com/lestrrat-go/jwx/v2/jwa"
-	"github.com/lestrrat-go/jwx/v2/jwk"
-	"github.com/lestrrat-go/jwx/v2/jwt"
-	"github.com/mathiasbq/hyperguild/ingestion/internal/auth"
-	"github.com/mathiasbq/hyperguild/ingestion/internal/mcp"
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-const testResourceMetadataURL = "https://brain-mcp.d-ma.be/.well-known/oauth-protected-resource"
-
-func okHandler() http.Handler {
-	return http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
-		w.WriteHeader(http.StatusOK)
-	})
-}
-
-func TestBearerAuth_MissingHeader(t *testing.T) {
-	handler := mcp.BearerAuth("secret", nil, "", okHandler())
-	req := httptest.NewRequest(http.MethodPost, "/mcp", nil)
-	rr := httptest.NewRecorder()
-	handler.ServeHTTP(rr, req)
-	assert.Equal(t, http.StatusUnauthorized, rr.Code)
-}
-
-func TestBearerAuth_WrongToken(t *testing.T) {
-	handler := mcp.BearerAuth("secret", nil, "", okHandler())
-	req := httptest.NewRequest(http.MethodPost, "/mcp", nil)
-	req.Header.Set("Authorization", "Bearer wrong")
-	rr := httptest.NewRecorder()
-	handler.ServeHTTP(rr, req)
-	assert.Equal(t, http.StatusUnauthorized, rr.Code)
-}
-
-func TestBearerAuth_CorrectToken(t *testing.T) {
-	called := false
-	handler := mcp.BearerAuth("secret", nil, "", http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
-		called = true
-		w.WriteHeader(http.StatusOK)
-	}))
-	req := httptest.NewRequest(http.MethodPost, "/mcp", nil)
-	req.Header.Set("Authorization", "Bearer secret")
-	rr := httptest.NewRecorder()
-	handler.ServeHTTP(rr, req)
-	assert.Equal(t, http.StatusOK, rr.Code)
-	assert.True(t, called)
-}
-
-func TestBearerAuth_EmptyConfiguredToken(t *testing.T) {
-	handler := mcp.BearerAuth("", nil, "", okHandler())
-	req := httptest.NewRequest(http.MethodPost, "/mcp", nil)
-	rr := httptest.NewRecorder()
-	handler.ServeHTTP(rr, req)
-	assert.Equal(t, http.StatusUnauthorized, rr.Code)
-}
-
-// Issue #9: a valid static Bearer must never emit a WWW-Authenticate header,
-// even when a resource-metadata URL is configured. The presence of that
-// header on a 200 response would flip MCP CLI clients into OAuth-discovery
-// mode and break static-Bearer auth from `.mcp.json` on Tailscale/LAN.
-func TestBearerAuth_ValidStaticBearer_NoWWWAuthenticate(t *testing.T) {
-	handler := mcp.BearerAuth("secret", nil, testResourceMetadataURL, okHandler())
-	req := httptest.NewRequest(http.MethodPost, "/mcp", nil)
-	req.Header.Set("Authorization", "Bearer secret")
-	rr := httptest.NewRecorder()
-	handler.ServeHTTP(rr, req)
-	assert.Equal(t, http.StatusOK, rr.Code)
-	assert.Empty(t, rr.Header().Get("WWW-Authenticate"), "static-Bearer 200 must not advertise OAuth")
-}
-
-// Issue #9: a 401 with resource-metadata configured must emit a
-// WWW-Authenticate header so claude.ai discovers the protected-resource
-// metadata document and continues the OAuth dance.
-func TestBearerAuth_Unauthorized_EmitsResourceMetadataChallenge(t *testing.T) {
-	handler := mcp.BearerAuth("secret", nil, testResourceMetadataURL, okHandler())
-	req := httptest.NewRequest(http.MethodPost, "/mcp", nil)
-	rr := httptest.NewRecorder()
-	handler.ServeHTTP(rr, req)
-	assert.Equal(t, http.StatusUnauthorized, rr.Code)
-	got := rr.Header().Get("WWW-Authenticate")
-	assert.Contains(t, got, `Bearer realm="brain"`)
-	assert.Contains(t, got, `resource_metadata="`+testResourceMetadataURL+`"`)
-}
-
-// Static-Bearer-only deployment: no resource-metadata URL, no challenge
-// header on 401 — matches pre-#9 behaviour for tests without Dex wired.
-func TestBearerAuth_Unauthorized_NoChallengeWhenResourceUnset(t *testing.T) {
-	handler := mcp.BearerAuth("secret", nil, "", okHandler())
-	req := httptest.NewRequest(http.MethodPost, "/mcp", nil)
-	rr := httptest.NewRecorder()
-	handler.ServeHTTP(rr, req)
-	assert.Equal(t, http.StatusUnauthorized, rr.Code)
-	assert.Empty(t, rr.Header().Get("WWW-Authenticate"))
-}
-
-// JWT auth tests
-
-func buildOIDCServer(t *testing.T) (*httptest.Server, jwk.Key) {
-	t.Helper()
-	raw, err := rsa.GenerateKey(rand.Reader, 2048)
-	require.NoError(t, err)
-	priv, err := jwk.FromRaw(raw)
-	require.NoError(t, err)
-	require.NoError(t, priv.Set(jwk.KeyIDKey, "k1"))
-	require.NoError(t, priv.Set(jwk.AlgorithmKey, jwa.RS256))
-	pub, err := jwk.PublicKeyOf(priv)
-	require.NoError(t, err)
-
-	set := jwk.NewSet()
-	require.NoError(t, set.AddKey(pub))
-	jwksBytes, err := json.Marshal(set)
-	require.NoError(t, err)
-
-	muxSrv := http.NewServeMux()
-	var srv *httptest.Server
-	muxSrv.HandleFunc("/.well-known/openid-configuration", func(w http.ResponseWriter, _ *http.Request) {
-		_ = json.NewEncoder(w).Encode(map[string]string{
-			"issuer":   srv.URL,
-			"jwks_uri": srv.URL + "/jwks",
-		})
-	})
-	muxSrv.HandleFunc("/jwks", func(w http.ResponseWriter, _ *http.Request) {
-		_, _ = w.Write(jwksBytes)
-	})
-	srv = httptest.NewServer(muxSrv)
-	t.Cleanup(srv.Close)
-	return srv, priv
-}
-
-func signJWT(t *testing.T, priv jwk.Key, issuer, audience string, exp time.Time) string {
-	t.Helper()
-	tok, err := jwt.NewBuilder().
-		Issuer(issuer).Audience([]string{audience}).
-		Subject("s").Expiration(exp).
-		Build()
-	require.NoError(t, err)
-	signed, err := jwt.Sign(tok, jwt.WithKey(jwa.RS256, priv))
-	require.NoError(t, err)
-	return string(signed)
-}
-
-func TestBearerAuth_ValidJWT(t *testing.T) {
-	oidcSrv, priv := buildOIDCServer(t)
-	v, err := auth.NewValidator(oidcSrv.URL, "brain")
-	require.NoError(t, err)
-
-	called := false
-	handler := mcp.BearerAuth("static-secret", v, "", http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
-		called = true
-		w.WriteHeader(http.StatusOK)
-	}))
-
-	token := signJWT(t, priv, oidcSrv.URL, "brain", time.Now().Add(time.Hour))
-	req := httptest.NewRequest(http.MethodPost, "/mcp", nil)
-	req.Header.Set("Authorization", "Bearer "+token)
-	rr := httptest.NewRecorder()
-	handler.ServeHTTP(rr, req)
-	assert.Equal(t, http.StatusOK, rr.Code)
-	assert.True(t, called)
-}
-
-func TestBearerAuth_InvalidJWT_FallsBackToStaticToken(t *testing.T) {
-	oidcSrv, _ := buildOIDCServer(t)
-	v, err := auth.NewValidator(oidcSrv.URL, "brain")
-	require.NoError(t, err)
-
-	handler := mcp.BearerAuth("static-secret", v, "", okHandler())
-	req := httptest.NewRequest(http.MethodPost, "/mcp", nil)
-	req.Header.Set("Authorization", "Bearer static-secret")
-	rr := httptest.NewRecorder()
-	handler.ServeHTTP(rr, req)
-	assert.Equal(t, http.StatusOK, rr.Code)
-}
-
-func TestBearerAuth_InvalidJWT_WrongStaticToken(t *testing.T) {
-	oidcSrv, priv := buildOIDCServer(t)
-	v, err := auth.NewValidator(oidcSrv.URL, "brain")
-	require.NoError(t, err)
-
-	handler := mcp.BearerAuth("static-secret", v, "", okHandler())
-	// Expired JWT — JWT fails, static token doesn't match either
-	token := signJWT(t, priv, oidcSrv.URL, "brain", time.Now().Add(-time.Hour))
-	req := httptest.NewRequest(http.MethodPost, "/mcp", nil)
-	req.Header.Set("Authorization", "Bearer "+token)
-
-	_ = context.Background() // satisfies import
-	rr := httptest.NewRecorder()
-	handler.ServeHTTP(rr, req)
-	assert.Equal(t, http.StatusUnauthorized, rr.Code)
-}