feat(mcp): audit-log every tools/call (OWASP MCP08)

tools/call dispatched with no record, so repo_delete, pr_merge and
file_delete left no trail in gitea-mcp; only auth acceptance was logged.

One slog record per call: tool, caller, token fingerprint, target
(owner/repo/number/branch/path/tag), outcome, duration. Every other
argument is reduced to args_bytes so the audit line never copies file
content or issue bodies.

Closes #64

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

.context/system-prompt.txt

@@ -78,6 +78,27 @@ These rules apply to every task across every project, regardless of harness.
    when a human reviewer outside the project is required. Document the reason in
    PROJECT.md.
 
+   **Exception — a GitOps repo where a branch cannot be reconciled.** In a repo whose
+   deployment watches one branch (`mathias/infra`: Flux watches `main`), a branch is
+   invisible to the thing that applies it. A `risk/medium` change to `alerts.yaml` or
+   `litellm-config.yaml` can be linted on a branch but never *exercised* there, so a
+   PR would buy a review of a state that was never deployed.
+
+   There, `risk/medium`+ work stays on `main` and instead requires a **recorded
+   adversarial review pass before the push** — `skills:pr-gatekeeper` or equivalent,
+   reviewing the staged diff. **The reviewer's verdict goes in the issue, not a PR
+   thread.** No verdict recorded means the lane was not used, and saying "the gate was
+   green" is not the same claim.
+
+   Be honest about what this is: a recorded *independent* pass, not four-eyes in the
+   sense `assessor-loop` §4.1 means for a regulated organisation, because the reviewer
+   is an agent. It is more than the repo had and less than the model it mirrors; do not
+   describe it as the stronger property. (infra#470, decided 2026-09-29.)
+
+   This lane depends on the `risk/` label being right. A label that triggers a heavier
+   lane is load-bearing, not cosmetic — if work that belongs in it is unlabelled, the
+   lane silently does not apply.
+
 6. **Close the loop — every substantive task ends with the same ritual.** Shipping
    the code is not the end of the task; capturing it is. Run this unprompted:
    - **Tag + bump SemVer** on the change (annotated tag; minor for a feature or
@@ -106,6 +127,43 @@ These rules apply to every task across every project, regardless of harness.
    revisit Y". Those are exactly the items that need a locator. If it is worth
    saying in a summary, it is worth writing where it can be found again without you.
 
+7. **Finish what's closable — only involve me for a genuine call.** If a
+   tracker issue, PR, or checklist item is demonstrably resolved — the fix
+   landed, the state changed, you verified it live — close/merge/check it off
+   in the same turn. Don't leave it open "for the record" or park it waiting
+   on me to confirm something that already happened; that's bookkeeping, not
+   a decision. Reserve asking me (`AskUserQuestion`, a `DECISION NEEDED`
+   comment, or otherwise pausing) for when it's genuinely mine to call:
+   irreversible or prod/host-impacting actions, a real judgment call with no
+   clearly-better option, ambiguous intent, or anything secret-writes/
+   destructive-git already gate. Before claiming something is closable,
+   verify it live (re-check the issue, re-run the command) rather than
+   trusting your own earlier summary (brain: `filed-issue-not-same-as-fixed`).
+
+8. **Control code needs an adversary, not a checklist.** Code whose job is to
+   refuse, deny, gate or contain is not adequately verified by a green gate.
+   Rule 5 makes CI the quality gate and that holds for ordinary work — but a
+   passing suite only asserts what its author already thought of, and for a
+   control the author is precisely the person whose imagination just failed.
+   Measured on `dispatch#75`: five review rounds, five real escapes verified by
+   execution, and **CI was green on every one of them** while `git rm
+   ././.dispatch-allow` deleted the file the control existed to protect. So
+   route this work through a review with authority to block, instructed to
+   verify by execution rather than by reading the implementation. Expect to be
+   blocked more than once; that is the control working, not the reviewer being
+   difficult. (brain: `a-green-gate-is-not-evidence-for-control-code`; the
+   practices live in the `pr-gatekeeper` agent.)
+
+9. **A test's name must not claim more than its assertions prove.** Name a test
+   after the mechanism it observes, not the goal it serves.
+   `DoesNotInheritEnv` is honest; `IsContained` is a claim the test cannot
+   support. This is not pedantry about naming — when name and assertion
+   diverge, the name wins in the reader's head and the gap becomes invisible,
+   which is what lets the defect survive review. Found three times in one PR,
+   twice in tests written to fix the previous instance of it; each passed while
+   the thing it was named for was exploitable. If you cannot name the mechanism,
+   you do not yet know what the test observes.
+
 ## CAD sprint patterns
 
 Two CAD sprint archetypes (defs: brain `wiki/homelab/decisions/continuous-agentic-development-cad-concept-2026-06-16`):
@@ -319,8 +377,20 @@ Workflow:
    and missing-untracked adapters). A drift fails the check with a
    message telling you to stage the regenerated files.
 
-Behavior rules in this file and per-project rules in `PROJECT.md` apply
+Behavior rules in this file and per-project rules in `PROJECT.md` apply on every
-unconditionally on every host, every harness.
+host and every harness.
+
+**Where a project rule contradicts a rule here, the project rule governs — and it
+must state its reason.** Both halves matter: the project file wins because it knows
+something this file cannot (infra's Flux constraint is real and not visible from
+here), and it must say why because a bare override is indistinguishable from drift.
+
+This replaces the previous wording, which said rules here and in `PROJECT.md` both
+apply *"unconditionally"*. That was not a tiebreak but a contradiction, and it went
+unnoticed until rule 5 and infra's "never create feature branches" had to be obeyed
+at the same time (infra#470). A standard can hold two individually sensible clauses
+that are jointly unsatisfiable, and survive for as long as everyone reads it
+charitably — the same failure the Inception Sprint Oath's G6 had.
 
 ## Engineering Skills
 

AGENTS.md

@@ -73,6 +73,27 @@ These rules apply to every task across every project, regardless of harness.
    when a human reviewer outside the project is required. Document the reason in
    PROJECT.md.
 
+   **Exception — a GitOps repo where a branch cannot be reconciled.** In a repo whose
+   deployment watches one branch (`mathias/infra`: Flux watches `main`), a branch is
+   invisible to the thing that applies it. A `risk/medium` change to `alerts.yaml` or
+   `litellm-config.yaml` can be linted on a branch but never *exercised* there, so a
+   PR would buy a review of a state that was never deployed.
+
+   There, `risk/medium`+ work stays on `main` and instead requires a **recorded
+   adversarial review pass before the push** — `skills:pr-gatekeeper` or equivalent,
+   reviewing the staged diff. **The reviewer's verdict goes in the issue, not a PR
+   thread.** No verdict recorded means the lane was not used, and saying "the gate was
+   green" is not the same claim.
+
+   Be honest about what this is: a recorded *independent* pass, not four-eyes in the
+   sense `assessor-loop` §4.1 means for a regulated organisation, because the reviewer
+   is an agent. It is more than the repo had and less than the model it mirrors; do not
+   describe it as the stronger property. (infra#470, decided 2026-09-29.)
+
+   This lane depends on the `risk/` label being right. A label that triggers a heavier
+   lane is load-bearing, not cosmetic — if work that belongs in it is unlabelled, the
+   lane silently does not apply.
+
 6. **Close the loop — every substantive task ends with the same ritual.** Shipping
    the code is not the end of the task; capturing it is. Run this unprompted:
    - **Tag + bump SemVer** on the change (annotated tag; minor for a feature or
@@ -101,6 +122,43 @@ These rules apply to every task across every project, regardless of harness.
    revisit Y". Those are exactly the items that need a locator. If it is worth
    saying in a summary, it is worth writing where it can be found again without you.
 
+7. **Finish what's closable — only involve me for a genuine call.** If a
+   tracker issue, PR, or checklist item is demonstrably resolved — the fix
+   landed, the state changed, you verified it live — close/merge/check it off
+   in the same turn. Don't leave it open "for the record" or park it waiting
+   on me to confirm something that already happened; that's bookkeeping, not
+   a decision. Reserve asking me (`AskUserQuestion`, a `DECISION NEEDED`
+   comment, or otherwise pausing) for when it's genuinely mine to call:
+   irreversible or prod/host-impacting actions, a real judgment call with no
+   clearly-better option, ambiguous intent, or anything secret-writes/
+   destructive-git already gate. Before claiming something is closable,
+   verify it live (re-check the issue, re-run the command) rather than
+   trusting your own earlier summary (brain: `filed-issue-not-same-as-fixed`).
+
+8. **Control code needs an adversary, not a checklist.** Code whose job is to
+   refuse, deny, gate or contain is not adequately verified by a green gate.
+   Rule 5 makes CI the quality gate and that holds for ordinary work — but a
+   passing suite only asserts what its author already thought of, and for a
+   control the author is precisely the person whose imagination just failed.
+   Measured on `dispatch#75`: five review rounds, five real escapes verified by
+   execution, and **CI was green on every one of them** while `git rm
+   ././.dispatch-allow` deleted the file the control existed to protect. So
+   route this work through a review with authority to block, instructed to
+   verify by execution rather than by reading the implementation. Expect to be
+   blocked more than once; that is the control working, not the reviewer being
+   difficult. (brain: `a-green-gate-is-not-evidence-for-control-code`; the
+   practices live in the `pr-gatekeeper` agent.)
+
+9. **A test's name must not claim more than its assertions prove.** Name a test
+   after the mechanism it observes, not the goal it serves.
+   `DoesNotInheritEnv` is honest; `IsContained` is a claim the test cannot
+   support. This is not pedantry about naming — when name and assertion
+   diverge, the name wins in the reader's head and the gap becomes invisible,
+   which is what lets the defect survive review. Found three times in one PR,
+   twice in tests written to fix the previous instance of it; each passed while
+   the thing it was named for was exploitable. If you cannot name the mechanism,
+   you do not yet know what the test observes.
+
 ## CAD sprint patterns
 
 Two CAD sprint archetypes (defs: brain `wiki/homelab/decisions/continuous-agentic-development-cad-concept-2026-06-16`):
@@ -314,8 +372,20 @@ Workflow:
    and missing-untracked adapters). A drift fails the check with a
    message telling you to stage the regenerated files.
 
-Behavior rules in this file and per-project rules in `PROJECT.md` apply
+Behavior rules in this file and per-project rules in `PROJECT.md` apply on every
-unconditionally on every host, every harness.
+host and every harness.
+
+**Where a project rule contradicts a rule here, the project rule governs — and it
+must state its reason.** Both halves matter: the project file wins because it knows
+something this file cannot (infra's Flux constraint is real and not visible from
+here), and it must say why because a bare override is indistinguishable from drift.
+
+This replaces the previous wording, which said rules here and in `PROJECT.md` both
+apply *"unconditionally"*. That was not a tiebreak but a contradiction, and it went
+unnoticed until rule 5 and infra's "never create feature branches" had to be obeyed
+at the same time (infra#470). A standard can hold two individually sensible clauses
+that are jointly unsatisfiable, and survive for as long as everyone reads it
+charitably — the same failure the Inception Sprint Oath's G6 had.
 
 ## Engineering Skills
 

internal/mcp/audit.go

@@ -0,0 +1,46 @@
+package mcp
+
+import (
+	"context"
+	"encoding/json"
+	"log/slog"
+	"time"
+
+	chassisauth "git.d-ma.be/mathias/mcp-chassis/auth"
+
+	"git.d-ma.be/mathias/gitea-mcp/internal/auth"
+	"git.d-ma.be/mathias/gitea-mcp/internal/gitea"
+)
+
+// auditTargetKeys are the only argument values copied into the audit record:
+// they identify what a call acted on without copying what it wrote. Every
+// other argument (file content, issue bodies) is reduced to args_bytes so the
+// audit trail never becomes a second copy of repo content (gitea-mcp#64).
+var auditTargetKeys = []string{"owner", "repo", "number", "branch", "path", "tag"}
+
+// logToolCall emits one structured record per tools/call (OWASP MCP08).
+func logToolCall(ctx context.Context, name string, args json.RawMessage, start time.Time, err error) {
+	attrs := []any{
+		"tool", name,
+		"caller", auth.Caller(ctx),
+		"args_bytes", len(args),
+		"duration_ms", time.Since(start).Milliseconds(),
+	}
+	if tok, ok := gitea.TokenFromContext(ctx); ok {
+		attrs = append(attrs, "token_fp", chassisauth.Fingerprint(tok))
+	}
+	var parsed map[string]any
+	if json.Unmarshal(args, &parsed) == nil {
+		for _, k := range auditTargetKeys {
+			if v, ok := parsed[k]; ok {
+				attrs = append(attrs, k, v)
+			}
+		}
+	}
+	outcome := "ok"
+	if err != nil {
+		outcome = err.Error()
+	}
+	attrs = append(attrs, "outcome", outcome)
+	slog.InfoContext(ctx, "mcp tool call", attrs...)
+}

internal/mcp/audit_test.go

@@ -0,0 +1,123 @@
+package mcp_test
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"git.d-ma.be/mathias/gitea-mcp/internal/auth"
+	"git.d-ma.be/mathias/gitea-mcp/internal/mcp"
+	"git.d-ma.be/mathias/gitea-mcp/internal/registry"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+type auditStubTool struct {
+	name string
+	err  error
+}
+
+func (s auditStubTool) Descriptor() registry.ToolDescriptor {
+	return registry.ToolDescriptor{Name: s.name, InputSchema: json.RawMessage(`{"type":"object"}`)}
+}
+
+func (s auditStubTool) Call(context.Context, json.RawMessage) (json.RawMessage, error) {
+	if s.err != nil {
+		return nil, s.err
+	}
+	return json.RawMessage(`{"ok":true}`), nil
+}
+
+// captureAudit routes slog to a buffer and returns the decoded
+// "mcp tool call" records emitted while fn runs.
+func captureAudit(t *testing.T, fn func()) []map[string]any {
+	t.Helper()
+	var buf bytes.Buffer
+	prev := slog.Default()
+	slog.SetDefault(slog.New(slog.NewJSONHandler(&buf, nil)))
+	t.Cleanup(func() { slog.SetDefault(prev) })
+
+	fn()
+
+	var out []map[string]any
+	for _, l := range strings.Split(strings.TrimSpace(buf.String()), "\n") {
+		if l == "" {
+			continue
+		}
+		var rec map[string]any
+		require.NoError(t, json.Unmarshal([]byte(l), &rec))
+		if rec["msg"] == "mcp tool call" {
+			out = append(out, rec)
+		}
+	}
+	return out
+}
+
+func auditServer(tools ...registry.Tool) http.Handler {
+	reg := registry.New()
+	for _, tl := range tools {
+		reg.Register(tl)
+	}
+	srv := mcp.NewServer(mcp.ServerOptions{Registry: reg})
+	return auth.CallerMiddleware(slog.Default(), srv)
+}
+
+func callTool(t *testing.T, h http.Handler, name string, args any) {
+	t.Helper()
+	body := map[string]any{
+		"jsonrpc": "2.0", "id": 1, "method": "tools/call",
+		"params": map[string]any{"name": name, "arguments": args},
+	}
+	b, err := json.Marshal(body)
+	require.NoError(t, err)
+	req := httptest.NewRequest(http.MethodPost, "/", bytes.NewBuffer(b))
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("X-Auth-Request-User", "alice")
+	h.ServeHTTP(httptest.NewRecorder(), req)
+}
+
+// gitea-mcp#64: tools/call dispatched with no record at all.
+func TestToolsCallLogsOneAuditRecordWithToolCallerAndTarget(t *testing.T) {
+	recs := captureAudit(t, func() {
+		callTool(t, auditServer(auditStubTool{name: "repo_delete"}), "repo_delete",
+			map[string]any{"owner": "mathias", "repo": "scratch", "confirm": "scratch"})
+	})
+	require.Len(t, recs, 1)
+	r := recs[0]
+	assert.Equal(t, "repo_delete", r["tool"])
+	assert.Equal(t, "alice", r["caller"])
+	assert.Equal(t, "mathias", r["owner"])
+	assert.Equal(t, "scratch", r["repo"])
+	assert.Equal(t, "ok", r["outcome"])
+	assert.Contains(t, r, "duration_ms")
+}
+
+func TestToolsCallAuditRecordsErrorOutcome(t *testing.T) {
+	recs := captureAudit(t, func() {
+		callTool(t, auditServer(auditStubTool{name: "pr_merge", err: errors.New("boom")}),
+			"pr_merge", map[string]any{"owner": "mathias", "repo": "x", "number": 3})
+	})
+	require.Len(t, recs, 1)
+	assert.Equal(t, "boom", recs[0]["outcome"])
+	assert.EqualValues(t, 3, recs[0]["number"])
+}
+
+// The audit line must not become a second copy of repo content.
+func TestToolsCallAuditOmitsArgumentValuesOtherThanTarget(t *testing.T) {
+	const sentinel = "SENTINEL-FILE-CONTENT-7f3a"
+	recs := captureAudit(t, func() {
+		callTool(t, auditServer(auditStubTool{name: "file_write_branch"}), "file_write_branch",
+			map[string]any{"owner": "mathias", "repo": "x", "path": "a.txt", "content": sentinel})
+	})
+	require.Len(t, recs, 1)
+	raw, err := json.Marshal(recs[0])
+	require.NoError(t, err)
+	assert.NotContains(t, string(raw), sentinel)
+	assert.Contains(t, recs[0], "args_bytes")
+}

internal/mcp/server.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"net/http"
+	"time"
 
 	"git.d-ma.be/mathias/gitea-mcp/internal/registry"
 )
@@ -90,7 +91,9 @@ func (s *Server) handlePOST(w http.ResponseWriter, r *http.Request) {
 				NewErrorResponse(req.ID, -32602, "invalid params", nil))
 			return
 		}
+		start := time.Now()
 		out, err := s.opts.Registry.Dispatch(r.Context(), p.Name, p.Arguments)
+		logToolCall(r.Context(), p.Name, p.Arguments, start, err)
 		if err != nil {
 			code := -32000
 			if errors.Is(err, registry.ErrToolNotFound) {

scripts/context-sync.sh

@@ -58,7 +58,7 @@ if [ "$FORCE" = false ]; then
     while IFS= read -r _match; do
       _lineno="${_match%%:*}"
       _content="${_match#*:}"
-      _token=$(printf '%s' "$_content" | grep -o '{{[^}]*}}' | head -1)
+      _token=$(head -1 < <(grep -o '{{[^}]*}}' <<<"$_content"))
       echo "  $PROJECT_FILE:$_lineno: unfilled placeholder $_token" >&2
     done <<< "$_placeholders"
     echo "" >&2