feat(brain): audit-log every tools/call; server-owned write provenance (#147)

Closes #144 (audit line per tools/call) and #145 (origin/written_by stamped on every model-reachable write, surfaced in brain_query/brain_get).

Passed pr-gatekeeper after four rounds of adversarial review, verified by execution: #147

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Co-authored-by: Mathias <mthbqv@gmail.com>

ingestion/internal/capturehttp/handler.go

@@ -104,6 +104,10 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// caller may have tried to put in the body.
 	in.Context.Principal = principal
 	in.Context.Origin = h.resolver.Resolve(principal, viaStatic)
+	in.Context.AuthPath = "jwt"
+	if viaStatic {
+		in.Context.AuthPath = "static"
+	}
 
 	rec, err := h.svc.Capture(r.Context(), in)
 	switch {

ingestion/internal/capturehttp/provenance_test.go

@@ -0,0 +1,51 @@
+package capturehttp_test
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/mathiasbq/hyperguild/ingestion/internal/audit"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/brainstore"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/capture"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/capturehttp"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/classification"
+)
+
+// The REST capture door derives AuthPath itself (hyperguild#145); a body
+// field cannot set it, and static vs JWT are told apart.
+func TestRESTCaptureStampsAuthPathFromAuthentication(t *testing.T) {
+	for _, tc := range []struct {
+		name, authz, wantOrigin, wantBy string
+		v                               capturehttp.Validator
+		sovereign                       []string
+	}{
+		{"static", "Bearer " + staticTok, "origin: static\n", "written_by: local-cli\n", nil, nil},
+		{"jwt", "Bearer jwt", "origin: jwt\n", "written_by: koala-cli\n", fakeValidator{subject: "koala-cli"}, []string{"koala-cli"}},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			brainDir := t.TempDir()
+			cfg, err := classification.Load(t.TempDir())
+			require.NoError(t, err)
+			svc := capture.NewService(brainstore.New(brainDir), fakeTracker{}, cfg, audit.NewSlogSink(nil))
+			h := capturehttp.New(svc, tc.v, staticTok, "local-cli", capturehttp.NewOriginResolver(tc.sovereign))
+			rr := do(t, h, tc.authz, map[string]any{
+				"context": map[string]any{
+					"harness": "claude-code", "actor": "mathias", "classification": "internal",
+					"AuthPath": "static", "auth_path": "static", "principal": "local-cli",
+				},
+				"insights": []map[string]any{{"text": "rest provenance probe", "wing": "hyperguild", "hall": "facts"}},
+			})
+			require.Equal(t, 200, rr.Code, rr.Body.String())
+			matches, _ := filepath.Glob(filepath.Join(brainDir, "wiki/hyperguild/facts/*.md"))
+			require.Len(t, matches, 1)
+			b, err := os.ReadFile(matches[0])
+			require.NoError(t, err)
+			assert.Contains(t, string(b), tc.wantOrigin)
+			assert.Contains(t, string(b), tc.wantBy)
+		})
+	}
+}