feat(create_project): resume=true makes substitution durable against infra#179 (#50, #51)

parallax#1 was the real-world evidence: infra#179's branch-writability stall
(>40s observed) blew past the tool's 5s budget, substitution ran zero files,
and the repo shipped genuinely broken (go.mod still read `module
__MODULE_PATH__`) — recoverable only via a manual clone/sed/git-mv/push.

Adds `resume: bool`. When true, skips template lookup and repo generation
entirely — the destination must already exist — and jumps straight to the
tree-walk substitution. This is safe to re-invoke repeatedly because
substituteEntry already compares against the branch's CURRENT state on every
call (GetTree is re-fetched fresh each time): a file already fixed in a prior
partial pass shows up already-correct or already-renamed and is a no-op. So the
actual blocker to resumability was purely the "destination must NOT exist"
guard on the create path — flipped it for resume, no change needed to the
substitution logic itself.

Consequences of resume existing:
- infra179FinalizeMessage (#46) now points at the concrete recovery — "call
  this tool again with resume=true" — instead of manual clone/sed guidance.
- "no placeholders substituted" only loud-fails on a FRESH create; on resume,
  finding nothing left to do is the expected steady state (success).
- dispatch_allow injection (#43) is now idempotent (read-before-write, update
  with sha if present-but-different, skip if already correct) so a resumed
  call with dispatch_allow=true doesn't error re-creating a path that already
  exists (#51's root cause).
- #51's other ask: dispatch_allow failures now land in their own
  dispatch_allow_failure field, never conflated with substitution's
  partial_failure — the two can independently succeed/fail.

Tests: resume with no destination (error, names "nothing to resume"), resume
continuing a partial substitution (asserts /generate is never re-called, only
the still-wrong file is rewritten), resume when already fully done (success,
not the fresh-create loud-fail), dispatch_allow idempotent re-injection
(two-phase test capturing the real written content, no test-visible knowledge
of the internal constant), and dispatch_allow_failure as a distinct field.

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

internal/tools/create_project_from_template.go

@@ -48,7 +48,7 @@ func NewCreateProjectFromTemplate(c *gitea.Client, a *allowlist.Allowlist, tmplO
 func (t *CreateProjectFromTemplate) Descriptor() registry.ToolDescriptor {
 	return registry.ToolDescriptor{
 		Name:        "create_project_from_template",
-		Description: "Create a new project repo from a template. Best-effort substitution of placeholders (__PROJECT_NAME__, __MODULE_PATH__) in every file's content AND path (e.g. renaming cmd/__PROJECT_NAME__/): it completes only if the generated branch is promptly writable. If gitea's async generate is slow (infra#179) the repo is still created and partial_failure explains how to finish substituting the placeholders manually. Check files_substituted and partial_failure. Defaults to the server-configured template; pass template_name to override (e.g. template-go-agent). Pass dispatch_allow=true to also inject a .dispatch-allow file so the project is immediately dispatch-eligible (dispatch#3).",
+		Description: "Create a new project repo from a template. Best-effort substitution of placeholders (__PROJECT_NAME__, __MODULE_PATH__) in every file's content AND path (e.g. renaming cmd/__PROJECT_NAME__/): it completes only if the generated branch is promptly writable. If gitea's async generate is slow (infra#179) the repo is still created and partial_failure explains the shortfall — call this tool again with resume=true (same owner/name) once the branch settles to safely continue where it left off; already-correct files/renames are left untouched. Check files_substituted, partial_failure, and dispatch_allow_failure. Defaults to the server-configured template; pass template_name to override (e.g. template-go-agent) — ignored when resume=true. Pass dispatch_allow=true to also inject a .dispatch-allow file so the project is dispatch-eligible (dispatch#3); safe to re-request on resume.",
 		InputSchema: json.RawMessage(`{
 			"type":"object",
 			"properties":{
@@ -56,8 +56,9 @@ func (t *CreateProjectFromTemplate) Descriptor() registry.ToolDescriptor {
 				"name":{"type":"string","pattern":"^[a-z][a-z0-9-]{1,38}[a-z0-9]$"},
 				"description":{"type":"string"},
 				"private":{"type":"boolean"},
-				"template_name":{"type":"string","description":"Template repo name to generate from. Defaults to the server-configured template."},
-				"dispatch_allow":{"type":"boolean","description":"When true, inject a .dispatch-allow file so the new project is immediately opt-in for headless dispatch (dispatch#3). Default false."}
+				"template_name":{"type":"string","description":"Template repo name to generate from. Defaults to the server-configured template. Ignored when resume=true."},
+				"dispatch_allow":{"type":"boolean","description":"When true, inject a .dispatch-allow file so the project is opt-in for headless dispatch (dispatch#3). Default false. Safe to re-request on resume."},
+				"resume":{"type":"boolean","description":"Resume substitution on an ALREADY-CREATED repo from a prior call that hit infra#179's branch-writability race (its partial_failure names this). Skips template lookup and repo generation entirely; the destination must already exist. Safe to call repeatedly — files/renames already correct are left untouched. Default false."}
 			},
 			"required":["owner","name"]
 		}`),
@@ -71,6 +72,7 @@ type createProjectArgs struct {
 	Private       bool   `json:"private"`
 	TemplateName  string `json:"template_name"`
 	DispatchAllow bool   `json:"dispatch_allow"`
+	Resume        bool   `json:"resume"`
 }
 
 // dispatchAllowContent is the body injected when dispatch_allow=true. Mirrors the
@@ -86,6 +88,7 @@ type createProjectResult struct {
 	DefaultBranch        string   `json:"default_branch"`
 	FilesSubstituted     []string `json:"files_substituted"`
 	PartialFailure       string   `json:"partial_failure,omitempty"`
+	DispatchAllowFailure string   `json:"dispatch_allow_failure,omitempty"`
 }
 
 func (t *CreateProjectFromTemplate) Call(ctx context.Context, raw json.RawMessage) (json.RawMessage, error) {
@@ -104,6 +107,87 @@ func (t *CreateProjectFromTemplate) Call(ctx context.Context, raw json.RawMessag
 		return nil, fmt.Errorf("name %q does not match pattern %s: %w", args.Name, nameRe.String(), gitea.ErrValidation)
 	}
 
+	var result createProjectResult
+	var branch string
+	var err error
+	if args.Resume {
+		result, branch, err = t.resumeDestination(ctx, args.Owner, args.Name)
+	} else {
+		result, branch, err = t.createDestination(ctx, args)
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	// Substitute across the WHOLE tree: content in every blob, plus a path rename
+	// for any file whose path carries a placeholder (e.g. cmd/__PROJECT_NAME__/main.go).
+	// A fixed known-files list can't rename directories or cover every templated
+	// file, which is why the old scaffold didn't build. GetTree reflects the
+	// branch's CURRENT state, which is what makes this loop safe to re-run on
+	// resume: a file already fixed in a prior partial pass shows up already-correct
+	// (or already-renamed) and substituteEntry is a no-op for it.
+	repls := substitutions(args.Owner, args.Name)
+	tree, terr := t.c.GetTree(ctx, args.Owner, args.Name, branch, true)
+	if terr != nil {
+		result.PartialFailure = fmt.Sprintf("tree walk (%s@%s): %v", args.Name, branch, terr)
+		return textOK(result)
+	}
+
+	for _, e := range tree.Tree {
+		if e.Type != "blob" {
+			continue
+		}
+		substituted, fail := t.substituteEntry(ctx, args.Owner, args.Name, branch, e.Path, repls)
+		if fail != "" {
+			result.PartialFailure = fail
+			break
+		}
+		if substituted != "" {
+			result.FilesSubstituted = append(result.FilesSubstituted, substituted)
+		}
+	}
+
+	// Opt the new project into headless dispatch if asked: presence of a
+	// .dispatch-allow file on the default branch marks it dispatch-eligible
+	// (dispatch#3). Skip if substitution itself already stalled — don't mark an
+	// incomplete repo dispatch-eligible. A failure here is reported in its OWN
+	// field (gitea-mcp#51) — it must never be indistinguishable from a
+	// substitution failure, since one can succeed while the other doesn't.
+	if args.DispatchAllow && result.PartialFailure == "" {
+		didWrite, fail := t.injectDispatchAllow(ctx, args.Owner, args.Name, branch)
+		if fail != "" {
+			result.DispatchAllowFailure = fail
+		} else if didWrite {
+			result.FilesSubstituted = append(result.FilesSubstituted, ".dispatch-allow")
+		}
+	}
+
+	// If substitution stalled because the generated branch wasn't writable in time,
+	// the repo IS created — say so clearly and point to the concrete recovery step
+	// (resume=true), rather than leaking the raw "branch does not exist" (infra#179:
+	// gitea's template-generate is slow-async on this instance, so tool-side
+	// substitution is best-effort).
+	if strings.Contains(result.PartialFailure, "branch does not exist") ||
+		strings.Contains(result.PartialFailure, "not found") {
+		result.PartialFailure = infra179FinalizeMessage(
+			branch, substitutionBudget, len(result.FilesSubstituted), result.PartialFailure)
+	}
+
+	// Fail loud on a FRESH create with nothing substituted: a real template
+	// should have placeholders, so finding none is suspicious. On resume, nothing
+	// left to substitute is the expected steady state once a prior partial run is
+	// fully caught up — success, not a loud failure.
+	if !args.Resume && result.PartialFailure == "" && len(result.FilesSubstituted) == 0 {
+		result.PartialFailure = fmt.Sprintf("no placeholders substituted in %s@%s — verify the scaffold is not left templated", args.Name, branch)
+	}
+
+	return textOK(result)
+}
+
+// createDestination generates a new repo from the template: verifies the
+// template exists and the destination doesn't already exist, then calls
+// gitea's /generate and resolves the default branch.
+func (t *CreateProjectFromTemplate) createDestination(ctx context.Context, args createProjectArgs) (createProjectResult, string, error) {
 	// Resolve template: per-call override takes precedence over the
 	// server-configured default. Owner stays server-configured.
 	tmplName := args.TemplateName
@@ -114,17 +198,19 @@ func (t *CreateProjectFromTemplate) Call(ctx context.Context, raw json.RawMessag
 	// Verify template exists and is marked as a template repo.
 	tmpl, err := t.c.GetRepo(ctx, t.templateOwner, tmplName)
 	if err != nil {
-		return nil, fmt.Errorf("template lookup: %w", err)
+		return createProjectResult{}, "", fmt.Errorf("template lookup: %w", err)
 	}
 	if !tmpl.Template {
-		return nil, fmt.Errorf("repo %s/%s is not marked as template: %w", t.templateOwner, tmplName, gitea.ErrValidation)
+		return createProjectResult{}, "", fmt.Errorf("repo %s/%s is not marked as template: %w", t.templateOwner, tmplName, gitea.ErrValidation)
 	}
 
 	// Verify destination doesn't already exist.
 	if _, err := t.c.GetRepo(ctx, args.Owner, args.Name); err == nil {
-		return nil, fmt.Errorf("destination %s/%s already exists: %w", args.Owner, args.Name, gitea.ErrConflict)
+		return createProjectResult{}, "", fmt.Errorf(
+			"destination %s/%s already exists: %w (pass resume:true to continue a prior partial create)",
+			args.Owner, args.Name, gitea.ErrConflict)
 	} else if !errors.Is(err, gitea.ErrNotFound) {
-		return nil, fmt.Errorf("destination check: %w", err)
+		return createProjectResult{}, "", fmt.Errorf("destination check: %w", err)
 	}
 
 	// Generate repo from template.
@@ -136,7 +222,7 @@ func (t *CreateProjectFromTemplate) Call(ctx context.Context, raw json.RawMessag
 		GitContent:  true,
 	})
 	if err != nil {
-		return nil, fmt.Errorf("generate: %w", err)
+		return createProjectResult{}, "", fmt.Errorf("generate: %w", err)
 	}
 
 	result := createProjectResult{
@@ -158,83 +244,76 @@ func (t *CreateProjectFromTemplate) Call(ctx context.Context, raw json.RawMessag
 		}
 	}
 	result.DefaultBranch = branch
+	return result, branch, nil
+}
 
-	// Substitute across the WHOLE tree: content in every blob, plus a path rename
-	// for any file whose path carries a placeholder (e.g. cmd/__PROJECT_NAME__/main.go).
-	// A fixed known-files list can't rename directories or cover every templated
-	// file, which is why the old scaffold didn't build.
-	repls := substitutions(args.Owner, args.Name)
-	tree, err := t.c.GetTree(ctx, args.Owner, args.Name, branch, true)
+// resumeDestination looks up an ALREADY-CREATED repo to continue substitution
+// on (gitea-mcp#50). It errors if the destination doesn't exist — resume has
+// nothing to resume without it. Template lookup and generation are skipped
+// entirely: resume only ever operates on the destination.
+func (t *CreateProjectFromTemplate) resumeDestination(ctx context.Context, owner, name string) (createProjectResult, string, error) {
+	repo, err := t.c.GetRepo(ctx, owner, name)
 	if err != nil {
-		result.PartialFailure = fmt.Sprintf("tree walk (%s@%s): %v", args.Name, branch, err)
-		return textOK(result)
+		if errors.Is(err, gitea.ErrNotFound) {
+			return createProjectResult{}, "", fmt.Errorf(
+				"resume:true but %s/%s does not exist — nothing to resume; omit resume to create it: %w",
+				owner, name, gitea.ErrValidation)
+		}
+		return createProjectResult{}, "", fmt.Errorf("resume destination check: %w", err)
+	}
+	branch := repo.DefaultBranch
+	if branch == "" {
+		branch = "main"
+	}
+	return createProjectResult{
+		FullName:      repo.FullName,
+		HTMLURL:       repo.HTMLURL,
+		CloneURL:      repo.CloneURL,
+		DefaultBranch: branch,
+	}, branch, nil
 }
 
-	for _, e := range tree.Tree {
-		if e.Type != "blob" {
-			continue
-		}
-		substituted, fail := t.substituteEntry(ctx, args.Owner, args.Name, branch, e.Path, repls)
-		if fail != "" {
-			result.PartialFailure = fail
-			break
-		}
-		if substituted != "" {
-			result.FilesSubstituted = append(result.FilesSubstituted, substituted)
+// injectDispatchAllow makes .dispatch-allow's presence idempotent (safe to call
+// on every resume, not just the first attempt): creates it if absent, updates
+// it if present but different, leaves it untouched if already correct. Without
+// this, a naive create-only write would error on a re-invoke (gitea rejects a
+// create at a path that already exists) — that was the reported failure in
+// gitea-mcp#51. Returns whether a write actually happened.
+func (t *CreateProjectFromTemplate) injectDispatchAllow(ctx context.Context, owner, name, branch string) (didWrite bool, failure string) {
+	const path = ".dispatch-allow"
+	sha := ""
+	if fc, err := t.c.GetFileContents(ctx, owner, name, path, branch); err == nil {
+		if decoded, derr := base64.StdEncoding.DecodeString(fc.Content); derr == nil && string(decoded) == dispatchAllowContent {
+			return false, "" // already present and correct — idempotent no-op
 		}
+		sha = fc.Sha // exists but differs (unexpected) — update it, don't blind-create
+	} else if !errors.Is(err, gitea.ErrNotFound) {
+		return false, fmt.Sprintf("read %s: %v", path, err)
 	}
 
-	// Opt the new project into headless dispatch if asked: presence of a
-	// .dispatch-allow file on the default branch marks it dispatch-eligible
-	// (dispatch#3). Ride the same upsertRetry path as substitution so it inherits
-	// the infra#179 branch-readiness / partial-failure handling below. Skip if the
-	// loop already stalled — a failed injection then degrades identically.
-	if args.DispatchAllow && result.PartialFailure == "" {
-		const dispatchAllowPath = ".dispatch-allow"
-		if err := t.upsertRetry(ctx, args.Owner, args.Name, dispatchAllowPath, gitea.UpsertFileArgs{
+	if err := t.upsertRetry(ctx, owner, name, path, gitea.UpsertFileArgs{
 		Branch:  branch,
 		Content: base64.StdEncoding.EncodeToString([]byte(dispatchAllowContent)),
 		Message: "dispatch: mark project dispatch-eligible (dispatch#3)",
+		Sha:     sha,
 	}); err != nil {
-			result.PartialFailure = fmt.Sprintf("write %s: %v", dispatchAllowPath, err)
-		} else {
-			result.FilesSubstituted = append(result.FilesSubstituted, dispatchAllowPath)
+		return false, fmt.Sprintf("write %s: %v", path, err)
 	}
-	}
-
-	// If substitution stalled because the generated branch wasn't writable in time,
-	// the repo IS created — say so clearly and point to the local finalize step,
-	// rather than leaking the raw "branch does not exist" (infra#179: gitea's
-	// template-generate is slow-async on this instance, so tool-side substitution
-	// is best-effort).
-	if strings.Contains(result.PartialFailure, "branch does not exist") ||
-		strings.Contains(result.PartialFailure, "not found") {
-		result.PartialFailure = infra179FinalizeMessage(
-			branch, substitutionBudget, len(result.FilesSubstituted), result.PartialFailure)
-	}
-
-	// Fail loud: a scaffold that still holds placeholders does not build. Nothing
-	// substituted (with no explicit failure) means the walk found no placeholders —
-	// suspicious for a real template. Surface it instead of returning silent success.
-	if result.PartialFailure == "" && len(result.FilesSubstituted) == 0 {
-		result.PartialFailure = fmt.Sprintf("no placeholders substituted in %s@%s — verify the scaffold is not left templated", args.Name, branch)
-	}
-
-	return textOK(result)
+	return true, ""
 }
 
 // infra179FinalizeMessage explains the best-effort outcome when gitea's slow
 // async template-generate (infra#179) leaves the branch unwritable within the
-// budget. It names the concrete remaining work — substituting the two
-// placeholders — rather than pointing at a specific tool, so the guidance stays
-// correct regardless of scaffolding-CLI state (gitea-mcp#46).
+// budget. It points at the concrete recovery step — re-invoking this same tool
+// with resume=true (gitea-mcp#50) — rather than a manual clone/sed/push, since
+// resume safely continues from wherever substitution stalled.
 func infra179FinalizeMessage(branch string, budget, done int, underlying string) string {
 	return fmt.Sprintf(
 		"repo created, but its branch (%s) was not writable within %ds — gitea's "+
 			"template-generate is slow-async on this instance (infra#179), so substitution "+
-			"is incomplete (%d file(s) done). Finish it by cloning the repo and replacing the "+
-			"remaining __PROJECT_NAME__ / __MODULE_PATH__ placeholders (in file contents and "+
-			"paths), then pushing; or retry create once the branch settles. Underlying: %s",
+			"is incomplete (%d file(s) done). Retry by calling this tool again with resume=true "+
+			"(same owner/name) once the branch is writable — it safely continues where this left "+
+			"off, skipping anything already correct. Underlying: %s",
 		branch, budget, done, underlying)
 }
 
@@ -243,7 +322,8 @@ func infra179FinalizeMessage(branch string, budget, done int, underlying string)
 // before the branch ref is committed, so writes 404 "branch does not exist" for a
 // window. We keep the budget SHORT so the MCP call stays responsive: a healthy
 // gitea commits in ~1s and this catches it; a slow one (infra#179, observed >40s)
-// fails fast and we defer substitution with clear guidance rather than hang.
+// fails fast with partial_failure naming resume=true as the recovery path
+// (gitea-mcp#50), rather than blocking the call for a minute-plus.
 const substitutionBudget = 5
 
 // upsertRetry retries UpsertFile on the transient post-generate "branch does not

internal/tools/create_project_from_template_test.go

@@ -33,6 +33,7 @@ type fakeTemplateServer struct {
 	files         map[string]string // path -> raw (un-substituted) content
 	genBranch     string            // default_branch returned by /generate ("" to force fallback)
 	generated     bool
+	generateCalls int // # times POST .../generate was hit — resume must never increment this
 	puts          []string
 	deletes       []string
 	putBodies     map[string]string // path -> decoded written content
@@ -43,6 +44,15 @@ func newFakeTemplateServer(files map[string]string, genBranch string) *fakeTempl
 	return &fakeTemplateServer{files: files, genBranch: genBranch, putBodies: map[string]string{}}
 }
 
+// newFakeTemplateServerResumed simulates a repo that already exists from a
+// prior (real) generate call — GET dest succeeds immediately, without a
+// /generate call first. Used for resume:true tests.
+func newFakeTemplateServerResumed(files map[string]string, genBranch string) *fakeTemplateServer {
+	f := newFakeTemplateServer(files, genBranch)
+	f.generated = true
+	return f
+}
+
 func (f *fakeTemplateServer) handler(t *testing.T, tmpl, dest string) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		f.mu.Lock()
@@ -65,6 +75,7 @@ func (f *fakeTemplateServer) handler(t *testing.T, tmpl, dest string) http.Handl
 
 		case r.Method == http.MethodPost && p == "/api/v1/repos/mathias/"+tmpl+"/generate":
 			f.generated = true
+			f.generateCalls++
 			w.WriteHeader(http.StatusCreated)
 			_, _ = fmt.Fprintf(w, `{"name":%q,"full_name":"mathias/%s","default_branch":%q,"clone_url":"http://gitea.example.com/mathias/%s.git","html_url":"http://gitea.example.com/mathias/%s","template":false}`,
 				dest, dest, f.genBranch, dest, dest)
@@ -139,6 +150,7 @@ type createOut struct {
 	DefaultBranch        string   `json:"default_branch"`
 	FilesSubstituted     []string `json:"files_substituted"`
 	PartialFailure       string   `json:"partial_failure,omitempty"`
+	DispatchAllowFailure string   `json:"dispatch_allow_failure,omitempty"`
 }
 
 // Happy path: whole-tree substitution, content + path rename, correct module host.
@@ -258,6 +270,126 @@ func TestCreateProject_DispatchAllow(t *testing.T) {
 	}
 }
 
+// ── resume: durable substitution against infra#179 (gitea-mcp#50) ───────────
+
+// resume:true requires an ALREADY-CREATED destination — there is nothing to
+// resume otherwise.
+func TestCreateProject_Resume_NoDestination_Errors(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
+		_, _ = w.Write([]byte(`{"message":"not found"}`))
+	}))
+	defer srv.Close()
+
+	_, err := newTool(srv.URL, "template-go-agent").Call(context.Background(),
+		json.RawMessage(`{"owner":"mathias","name":"new-svc","resume":true}`))
+	require.Error(t, err)
+	assert.ErrorIs(t, err, gitea.ErrValidation)
+	assert.Contains(t, err.Error(), "nothing to resume")
+}
+
+// resume:true on an existing repo continues substitution — fixes only what's
+// still wrong, leaves already-correct files untouched, and never calls
+// /generate again (the whole point: no re-creation, just continuation).
+func TestCreateProject_Resume_ContinuesPartialSubstitution(t *testing.T) {
+	files := map[string]string{
+		"go.mod":    "module git.d-ma.be/mathias/new-svc\n", // already correct from a prior partial run
+		"README.md": "# __PROJECT_NAME__\n",                 // still needs substitution
+	}
+	f := newFakeTemplateServerResumed(files, "main")
+	srv := httptest.NewServer(f.handler(t, "template-go-agent", "new-svc"))
+	defer srv.Close()
+
+	out := callTool(t, srv.URL, "template-go-agent", `{"owner":"mathias","name":"new-svc","resume":true}`)
+
+	assert.Empty(t, out.PartialFailure)
+	assert.Equal(t, 0, f.generateCalls, "resume must never call /generate")
+	assert.Contains(t, out.FilesSubstituted, "README.md")
+	assert.NotContains(t, out.FilesSubstituted, "go.mod", "already-correct file must not be re-reported")
+	assert.NotContains(t, f.puts, "go.mod", "already-correct file must not be rewritten")
+	assert.Contains(t, f.puts, "README.md")
+}
+
+// resume:true when everything is already substituted is the expected steady
+// state (a prior resume already finished the job, or this is a redundant
+// re-invoke) — success, NOT the "no placeholders substituted" loud failure
+// that a fresh (non-resume) create would trigger.
+func TestCreateProject_Resume_AlreadyFullyDone_IsSuccess(t *testing.T) {
+	files := map[string]string{
+		"go.mod":    "module git.d-ma.be/mathias/new-svc\n",
+		"README.md": "# new-svc\n",
+	}
+	f := newFakeTemplateServerResumed(files, "main")
+	srv := httptest.NewServer(f.handler(t, "template-go-agent", "new-svc"))
+	defer srv.Close()
+
+	out := callTool(t, srv.URL, "template-go-agent", `{"owner":"mathias","name":"new-svc","resume":true}`)
+
+	assert.Empty(t, out.FilesSubstituted)
+	assert.Empty(t, out.PartialFailure, "nothing left to do on resume must be success, not a loud failure")
+}
+
+// dispatch_allow injection is idempotent on resume: if .dispatch-allow already
+// has the correct content (from an earlier successful injection), re-invoking
+// must not attempt another write — and must not error the way a naive
+// create-only write would (gitea 409/422 on an existing path with no sha).
+func TestCreateProject_Resume_DispatchAllowIdempotent(t *testing.T) {
+	// Phase 1: a normal (non-resume) call captures the REAL content the tool
+	// writes for .dispatch-allow, without the test needing to know the exact
+	// unexported constant.
+	seedFiles := map[string]string{"go.mod": "module __MODULE_PATH__\n"}
+	seedSrv := newFakeTemplateServer(seedFiles, "main")
+	srv1 := httptest.NewServer(seedSrv.handler(t, "template-go-agent", "new-svc"))
+	out1 := callTool(t, srv1.URL, "template-go-agent", `{"owner":"mathias","name":"new-svc","dispatch_allow":true}`)
+	srv1.Close()
+	require.Empty(t, out1.PartialFailure)
+	realContent := seedSrv.putBodies[".dispatch-allow"]
+	require.NotEmpty(t, realContent, "phase 1 must have written .dispatch-allow")
+
+	// Phase 2: resume with .dispatch-allow ALREADY at that exact content, plus
+	// one file still needing substitution.
+	files := map[string]string{
+		".dispatch-allow": realContent,
+		"README.md":       "# __PROJECT_NAME__\n",
+	}
+	f := newFakeTemplateServerResumed(files, "main")
+	srv2 := httptest.NewServer(f.handler(t, "template-go-agent", "new-svc"))
+	defer srv2.Close()
+
+	out2 := callTool(t, srv2.URL, "template-go-agent", `{"owner":"mathias","name":"new-svc","resume":true,"dispatch_allow":true}`)
+
+	assert.Empty(t, out2.PartialFailure)
+	assert.Empty(t, out2.DispatchAllowFailure)
+	assert.NotContains(t, f.puts, ".dispatch-allow", "already-correct .dispatch-allow must not be rewritten")
+	assert.NotContains(t, out2.FilesSubstituted, ".dispatch-allow", "unchanged file must not be reported as substituted")
+	assert.Contains(t, out2.FilesSubstituted, "README.md")
+}
+
+// dispatch_allow injection failing is reported in its OWN field, distinct from
+// PartialFailure (gitea-mcp#51) — substitution can succeed while dispatch
+// eligibility still fails, and the caller must be able to tell them apart.
+func TestCreateProject_DispatchAllowFailure_IsDistinctField(t *testing.T) {
+	files := map[string]string{"go.mod": "module __MODULE_PATH__\n"}
+	f := newFakeTemplateServer(files, "main")
+	base := f.handler(t, "template-go-agent", "new-svc")
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if strings.Contains(r.URL.Path, "/contents/.dispatch-allow") {
+			w.WriteHeader(http.StatusInternalServerError)
+			_, _ = w.Write([]byte(`{"message":"boom"}`))
+			return
+		}
+		base(w, r)
+	}))
+	defer srv.Close()
+
+	out := callTool(t, srv.URL, "template-go-agent", `{"owner":"mathias","name":"new-svc","dispatch_allow":true}`)
+
+	assert.Empty(t, out.PartialFailure, "substitution itself succeeded — must not be conflated with the dispatch failure")
+	assert.NotEmpty(t, out.DispatchAllowFailure)
+	assert.Contains(t, out.DispatchAllowFailure, ".dispatch-allow")
+	assert.Contains(t, out.FilesSubstituted, "go.mod", "substitution must still be reported despite the separate dispatch failure")
+}
+
 // ── guardrails unchanged by the rewrite ──────────────────────────────────────
 
 func TestCreateProject_NameRegexFailure(t *testing.T) {

internal/tools/create_project_internal_test.go

@@ -6,12 +6,13 @@ import (
 )
 
 // #46: the infra#179 finalize guidance must not point at a non-existent command
-// (`hyperguild new-project` was never built). It should name the real remaining
-// work — substituting the placeholders — so the caller isn't sent to a dead end.
+// (`hyperguild new-project` was never built). #50 superseded the original
+// manual-editing guidance with a concrete, real recovery: re-invoke this same
+// tool with resume=true.
 func TestInfra179FinalizeMessage(t *testing.T) {
 	msg := infra179FinalizeMessage("main", 5, 2, "branch does not exist")
 
-	for _, want := range []string{"infra#179", "__PROJECT_NAME__", "__MODULE_PATH__", "branch does not exist"} {
+	for _, want := range []string{"infra#179", "resume=true", "branch does not exist"} {
 		if !strings.Contains(msg, want) {
 			t.Errorf("message missing %q\ngot: %s", want, msg)
 		}