feat(tools): add tbd_ship — CI-gated trunk-based ship (#40)

An intent verb for the trunk-based loop: branch from base → write the file →
open a PR → auto-merge (squash) → delete the branch. One call instead of
orchestrating file_write_branch + pr_create + workflow_run_status + pr_merge +
branch_delete and remembering the conventions each time.

The load-bearing safety is a pure, fail-closed CI gate (evaluateShipGate):
merge=true ONLY when every workflow run for the PR head commit is
completed+success AND the base branch is not review-protected. Every other
state — CI pending / red / absent, review-required base, or an unclean merge —
fails closed to PR-only and returns the PR with a reason. A change with no CI
gate is never auto-merged to trunk (cf. agentsquad#36: non-compiling code
reviewer-approved straight to main with no CI wall).

- ci_timeout_seconds polls the head commit's runs to completion (default 0 =
  snapshot, returns pending right after opening the PR).
- Derives a deterministic short-lived branch (tbd/<slug>-<hash>); handles new
  and existing files (fetches the blob sha for updates).
- Adds head.sha + mergeable to the PR struct.
- Tests: full gate matrix (green/pending/red/cancelled/none/mixed/protected) +
  Call happy-merge, no-CI fail-closed, red fail-closed, allowlist.

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

internal/tools/tbd_ship_test.go

@@ -0,0 +1,116 @@
+package tools_test
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"sync/atomic"
+	"testing"
+
+	"git.d-ma.be/mathias/gitea-mcp/internal/allowlist"
+	"git.d-ma.be/mathias/gitea-mcp/internal/gitea"
+	"git.d-ma.be/mathias/gitea-mcp/internal/tools"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// shipFake serves the whole tbd_ship flow; runsJSON is the workflow_runs array
+// for the head commit, letting each test drive the CI gate.
+func shipFake(t *testing.T, runsJSON string, merged, deleted *atomic.Bool) *httptest.Server {
+	t.Helper()
+	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		p := r.URL.Path
+		w.Header().Set("Content-Type", "application/json")
+		switch {
+		case r.Method == http.MethodGet && strings.Contains(p, "/branch_protections/"):
+			w.WriteHeader(http.StatusNotFound) // unprotected
+			_, _ = w.Write([]byte(`{"message":"not found"}`))
+		case r.Method == http.MethodPost && strings.HasSuffix(p, "/branches"):
+			w.WriteHeader(http.StatusCreated)
+			_, _ = w.Write([]byte(`{"name":"tbd/x","commit":{"id":"abc"}}`))
+		case r.Method == http.MethodGet && strings.Contains(p, "/contents/"):
+			w.WriteHeader(http.StatusNotFound) // new file
+			_, _ = w.Write([]byte(`{"message":"not found"}`))
+		case (r.Method == http.MethodPost || r.Method == http.MethodPut) && strings.Contains(p, "/contents/"):
+			w.WriteHeader(http.StatusCreated)
+			_, _ = w.Write([]byte(`{"content":{"path":"x","sha":"s"},"commit":{"sha":"c"}}`))
+		case r.Method == http.MethodPost && strings.HasSuffix(p, "/pulls"):
+			w.WriteHeader(http.StatusCreated)
+			_, _ = w.Write([]byte(`{"number":7,"title":"t","html_url":"http://x/pulls/7","state":"open","head":{"ref":"tbd/x","sha":"abc"},"base":{"ref":"main"}}`))
+		case r.Method == http.MethodGet && strings.Contains(p, "/actions/runs"):
+			_, _ = w.Write([]byte(`{"total_count":0,"workflow_runs":` + runsJSON + `}`))
+		case r.Method == http.MethodPost && strings.HasSuffix(p, "/pulls/7/merge"):
+			merged.Store(true)
+			w.WriteHeader(http.StatusOK)
+			_, _ = w.Write([]byte(`{}`))
+		case r.Method == http.MethodDelete && strings.Contains(p, "/branches/"):
+			deleted.Store(true)
+			w.WriteHeader(http.StatusOK)
+			_, _ = w.Write([]byte(`{}`))
+		default:
+			t.Errorf("unexpected request: %s %s", r.Method, p)
+			w.WriteHeader(http.StatusNotFound)
+		}
+	}))
+}
+
+func callShip(t *testing.T, srvURL, args string) map[string]any {
+	t.Helper()
+	tool := tools.NewTBDShip(gitea.NewClient(srvURL, "tok"), allowlist.New([]string{"mathias"}))
+	out, err := tool.Call(context.Background(), json.RawMessage(args))
+	require.NoError(t, err)
+	var res map[string]any
+	require.NoError(t, json.Unmarshal(out, &res))
+	return res
+}
+
+// Green CI + unprotected base → squash-merge + branch deleted.
+func TestTBDShip_GreenCI_Merges(t *testing.T) {
+	var merged, deleted atomic.Bool
+	srv := shipFake(t, `[{"id":1,"status":"completed","conclusion":"success","head_sha":"abc"}]`, &merged, &deleted)
+	defer srv.Close()
+
+	res := callShip(t, srv.URL, `{"owner":"mathias","repo":"myrepo","path":"docs/x.md","content":"hi","message":"add x"}`)
+
+	assert.Equal(t, true, res["merged"])
+	assert.Equal(t, "success", res["ci_status"])
+	assert.Equal(t, float64(7), res["pr_number"])
+	assert.True(t, merged.Load(), "merge endpoint must be called")
+	assert.True(t, deleted.Load(), "branch must be deleted after merge")
+}
+
+// No CI runs for the head commit → fail closed: PR opened, NOT merged.
+func TestTBDShip_NoCI_FailsClosed(t *testing.T) {
+	var merged, deleted atomic.Bool
+	srv := shipFake(t, `[]`, &merged, &deleted)
+	defer srv.Close()
+
+	res := callShip(t, srv.URL, `{"owner":"mathias","repo":"myrepo","path":"docs/x.md","content":"hi","message":"add x"}`)
+
+	assert.Equal(t, false, res["merged"])
+	assert.Equal(t, "none", res["ci_status"])
+	assert.NotEmpty(t, res["reason"])
+	assert.False(t, merged.Load(), "merge must NOT be called when there is no CI")
+	assert.Equal(t, float64(7), res["pr_number"], "PR is still opened for manual merge")
+}
+
+// Red CI → fail closed.
+func TestTBDShip_RedCI_FailsClosed(t *testing.T) {
+	var merged, deleted atomic.Bool
+	srv := shipFake(t, `[{"id":1,"status":"completed","conclusion":"failure","head_sha":"abc"}]`, &merged, &deleted)
+	defer srv.Close()
+
+	res := callShip(t, srv.URL, `{"owner":"mathias","repo":"myrepo","path":"docs/x.md","content":"hi","message":"add x"}`)
+
+	assert.Equal(t, false, res["merged"])
+	assert.Equal(t, "failed", res["ci_status"])
+	assert.False(t, merged.Load(), "merge must NOT be called when CI is red")
+}
+
+func TestTBDShip_AllowlistRejects(t *testing.T) {
+	tool := tools.NewTBDShip(gitea.NewClient("http://unused", ""), allowlist.New([]string{"mathias"}))
+	_, err := tool.Call(context.Background(), json.RawMessage(`{"owner":"evil","repo":"r","path":"p","content":"c","message":"m"}`))
+	require.Error(t, err)
+}