feat(create_project): dispatch_allow also registers the repo into dispatch's allowlist (#54)

Extends the existing dispatch_allow flag (which already injects .dispatch-allow,
#43/#51/#53) to also append owner/name to mathias/dispatch's git-tracked
dispatch-repos.txt (dispatch#19) — the second of the two required dispatch
gates. Being listed there is necessary but not sufficient on its own (the repo
still needs its own .dispatch-allow marker) — both are applied independently,
neither implies the other, matching dispatch#3's structural trust-zone design
where both must say yes.

Idempotent: a repo already listed (e.g. dispatch_allow re-requested on resume)
is a no-op, not a duplicate line. Failure is reported in its own
dispatch_allowlist_failure field, distinct from partial_failure (substitution)
and dispatch_allow_failure (the marker file) — the three gates can each fail
independently, never conflated (same principle as #51).

The allowlist owner/repo/path/branch are hardcoded to match mathias/dispatch's
own DISPATCH_ALLOWLIST_* env defaults, confirmed unoverridden in the live
CronJob (2026-07-06) before implementing.

Tests: fresh registration (existing entries preserved, not clobbered),
already-listed no-op (zero writes), allowlist-write failure as a distinct
field, dispatch_allow=false never touches the file.

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

internal/tools/create_project_from_template.go

@@ -57,7 +57,7 @@ func (t *CreateProjectFromTemplate) Descriptor() registry.ToolDescriptor {
 				"description":{"type":"string"},
 				"private":{"type":"boolean"},
 				"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."},
+				"dispatch_allow":{"type":"boolean","description":"When true, inject a .dispatch-allow file (dispatch#3) AND register owner/name into mathias/dispatch's git-tracked allowlist (dispatch-repos.txt, dispatch#19) — both gates are required for the watcher to actually pick the repo up; each is applied independently and idempotently. 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"]
@@ -82,15 +82,28 @@ const dispatchAllowContent = "# Presence of this file marks this repo as opt-in
 	"# See dispatch#3.\n"
 
 type createProjectResult struct {
-	FullName             string   `json:"full_name"`
-	HTMLURL              string   `json:"html_url"`
-	CloneURL             string   `json:"clone_url"`
-	DefaultBranch        string   `json:"default_branch"`
-	FilesSubstituted     []string `json:"files_substituted"`
-	PartialFailure       string   `json:"partial_failure,omitempty"`
-	DispatchAllowFailure string   `json:"dispatch_allow_failure,omitempty"`
+	FullName                 string   `json:"full_name"`
+	HTMLURL                  string   `json:"html_url"`
+	CloneURL                 string   `json:"clone_url"`
+	DefaultBranch            string   `json:"default_branch"`
+	FilesSubstituted         []string `json:"files_substituted"`
+	PartialFailure           string   `json:"partial_failure,omitempty"`
+	DispatchAllowFailure     string   `json:"dispatch_allow_failure,omitempty"`
+	DispatchAllowlisted      bool     `json:"dispatch_allowlisted,omitempty"`
+	DispatchAllowlistFailure string   `json:"dispatch_allowlist_failure,omitempty"`
 }
 
+// The dispatch allowlist (dispatch#19) is a fixed integration point — a
+// specific file in a specific repo the mathias/dispatch watcher reads at the
+// start of every cycle. Hardcoded to match its own DISPATCH_ALLOWLIST_OWNER/
+// _REPO/_PATH defaults (unconfigured in the live CronJob, confirmed 2026-07-06).
+const (
+	dispatchAllowlistOwner  = "mathias"
+	dispatchAllowlistRepo   = "dispatch"
+	dispatchAllowlistPath   = "dispatch-repos.txt"
+	dispatchAllowlistBranch = "main"
+)
+
 func (t *CreateProjectFromTemplate) Call(ctx context.Context, raw json.RawMessage) (json.RawMessage, error) {
 	var args createProjectArgs
 	if err := parseArgs(raw, &args); err != nil {
@@ -147,19 +160,26 @@ func (t *CreateProjectFromTemplate) Call(ctx context.Context, raw json.RawMessag
 		}
 	}
 
-	// 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.
+	// Opt the new project into headless dispatch if asked. Two INDEPENDENT gates,
+	// both required (dispatch#3 + dispatch#19): the .dispatch-allow marker on this
+	// repo, and this repo's owner/name listed in mathias/dispatch's git-tracked
+	// allowlist. Skip both if substitution itself already stalled — don't mark an
+	// incomplete repo dispatch-eligible. Each failure is reported in its OWN field
+	// (gitea-mcp#51/#54) — never conflated with each other or with substitution,
+	// since any one of the three can fail independently of the other two.
 	if args.DispatchAllow && result.PartialFailure == "" {
-		didWrite, fail := t.injectDispatchAllow(ctx, args.Owner, args.Name, branch)
-		if fail != "" {
+		if didWrite, fail := t.injectDispatchAllow(ctx, args.Owner, args.Name, branch); fail != "" {
 			result.DispatchAllowFailure = fail
 		} else if didWrite {
 			result.FilesSubstituted = append(result.FilesSubstituted, ".dispatch-allow")
 		}
+
+		ownerName := args.Owner + "/" + args.Name
+		if didRegister, fail := t.registerDispatchAllowlist(ctx, ownerName); fail != "" {
+			result.DispatchAllowlistFailure = fail
+		} else if didRegister {
+			result.DispatchAllowlisted = true
+		}
 	}
 
 	// If substitution stalled because the generated branch wasn't writable in time,
@@ -302,6 +322,42 @@ func (t *CreateProjectFromTemplate) injectDispatchAllow(ctx context.Context, own
 	return true, ""
 }
 
+// registerDispatchAllowlist appends ownerName ("owner/name") to
+// mathias/dispatch's git-tracked dispatch-repos.txt if not already listed
+// (gitea-mcp#54) — idempotent, safe to call on every resume. This is the
+// SECOND of the two required dispatch gates: being listed here is necessary
+// but not sufficient on its own (the repo also needs its own .dispatch-allow
+// marker, injectDispatchAllow's job) — dispatch#3's structural trust-zone
+// design requires both independently. Returns whether a write actually
+// happened, so the caller only reports a fresh registration, not a no-op.
+func (t *CreateProjectFromTemplate) registerDispatchAllowlist(ctx context.Context, ownerName string) (didRegister bool, failure string) {
+	fc, err := t.c.GetFileContents(ctx, dispatchAllowlistOwner, dispatchAllowlistRepo, dispatchAllowlistPath, dispatchAllowlistBranch)
+	if err != nil {
+		return false, fmt.Sprintf("read %s/%s:%s: %v", dispatchAllowlistOwner, dispatchAllowlistRepo, dispatchAllowlistPath, err)
+	}
+	decoded, err := base64.StdEncoding.DecodeString(fc.Content)
+	if err != nil {
+		return false, fmt.Sprintf("decode %s: %v", dispatchAllowlistPath, err)
+	}
+	content := string(decoded)
+	for _, line := range strings.Split(content, "\n") {
+		if strings.TrimSpace(line) == ownerName {
+			return false, "" // already listed — idempotent no-op
+		}
+	}
+
+	newContent := strings.TrimRight(content, "\n") + "\n" + ownerName + "\n"
+	if _, err := t.c.UpsertFile(ctx, dispatchAllowlistOwner, dispatchAllowlistRepo, dispatchAllowlistPath, gitea.UpsertFileArgs{
+		Branch:  dispatchAllowlistBranch,
+		Content: base64.StdEncoding.EncodeToString([]byte(newContent)),
+		Message: fmt.Sprintf("chore(allowlist): opt in %s for headless dispatch", ownerName),
+		Sha:     fc.Sha,
+	}); err != nil {
+		return false, fmt.Sprintf("append to %s/%s:%s: %v", dispatchAllowlistOwner, dispatchAllowlistRepo, dispatchAllowlistPath, err)
+	}
+	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 points at the concrete recovery step — re-invoking this same tool