fix(server): worktree threads survive a local branch named t3code

apps/server/src/orchestration-v2/ThreadLaunchService.test.ts

@@ -99,6 +99,7 @@ interface HarnessOptions {
   readonly managedFolders?: Layer.Layer<ManagedProjectFolders.ManagedProjectFolders>;
   readonly createWorktree?: GitWorkflow.GitWorkflowService["Service"]["createWorktree"];
   readonly fetchRemote?: GitWorkflow.GitWorkflowService["Service"]["fetchRemote"];
+  readonly hasCommit?: GitWorkflow.GitWorkflowService["Service"]["hasCommit"];
   readonly renameBranch?: GitWorkflow.GitWorkflowService["Service"]["renameBranch"];
   readonly runSetup?: ProjectSetupScriptRunner.ProjectSetupScriptRunner["Service"]["runForThread"];
   readonly generateTitle?: TextGeneration.TextGeneration["Service"]["generateThreadTitle"];
@@ -167,6 +168,7 @@ function makeHarness(options: HarnessOptions = {}) {
       createWorktree,
       renameBranch,
       fetchRemote: options.fetchRemote ?? (() => Effect.void),
+      hasCommit: options.hasCommit ?? (() => Effect.succeed(false)),
       remoteExists: () => Effect.succeed(true),
       remoteBranchExists: () => Effect.succeed(true),
       removeWorktree,
@@ -1165,6 +1167,37 @@ it.effect("renames a temporary t3code/<hash> branch off the provisioning critica
   }),
 );
 
+it.effect("provisions under t3code-<hash> when a plain t3code branch blocks t3code/*", () =>
+  Effect.gen(function* () {
+    const harness = makeHarness({
+      hasCommit: (input) => Effect.succeed(input.refName === "refs/heads/t3code"),
+      createWorktree: (input) =>
+        Effect.succeed({
+          worktree: { path: "/repo-worktrees/temp", refName: input.newRefName, headSha: "abc" },
+        } as never),
+    });
+    yield* Effect.gen(function* () {
+      const launches = yield* ThreadLaunch.ThreadLaunchService;
+      const threads = yield* ThreadManagement.ThreadManagementService;
+      const launched = yield* launches.launch(
+        launchInput({
+          command: "command:launch:blocked-namespace",
+          thread: "thread:launch:blocked-namespace",
+          message: "Build the feature",
+          workspace: { type: "worktree", baseRef: "main", branch: "t3code/abcd1234" },
+        }),
+      );
+      yield* waitUntil(() =>
+        threads
+          .getThreadProjection(launched.threadId)
+          .pipe(Effect.map((projection) => projection.thread.branch === "generated-branch")),
+      );
+      assert.equal(harness.createWorktree.mock.calls[0]?.[0]?.newRefName, "t3code-abcd1234");
+      assert.equal(harness.renameBranch.mock.calls[0]?.[0]?.oldBranch, "t3code-abcd1234");
+    }).pipe(Effect.provide(harness.layer));
+  }),
+);
+
 it.effect("keeps an explicit branch name instead of generating one", () =>
   Effect.gen(function* () {
     const harness = makeHarness();

apps/server/src/orchestration-v2/ThreadLaunchService.ts

@@ -28,7 +28,12 @@ import * as Option from "effect/Option";
 import * as Ref from "effect/Ref";
 import * as Schema from "effect/Schema";
 import * as Scope from "effect/Scope";
-import { buildTemporaryWorktreeBranchName, isTemporaryWorktreeBranch } from "@t3tools/shared/git";
+import {
+  buildTemporaryWorktreeBranchName,
+  flattenTemporaryWorktreeBranchName,
+  isTemporaryWorktreeBranch,
+  WORKTREE_BRANCH_PREFIX,
+} from "@t3tools/shared/git";
 
 import * as GitWorkflow from "../git/GitWorkflowService.ts";
 import * as ProjectService from "../project/ProjectService.ts";
@@ -363,6 +368,18 @@ const make = Effect.gen(function* () {
           }
         }
         if (startFromOrigin) yield* setupTracker.stageStatus(threadId, "fetch", "done");
+        if (
+          branch !== null &&
+          isTemporaryWorktreeBranch(branch) &&
+          (yield* git
+            .hasCommit({
+              cwd: project.workspaceRoot,
+              refName: `refs/heads/${WORKTREE_BRANCH_PREFIX}`,
+            })
+            .pipe(Effect.mapError(mapError(input, "provision-worktree", threadId))))
+        ) {
+          branch = flattenTemporaryWorktreeBranchName(branch);
+        }
         yield* setupTracker.stageStatus(threadId, "checkout", "running");
         const worktree = yield* git
           .createWorktree(

packages/shared/src/git.test.ts

@@ -5,6 +5,7 @@ import {
   applyGitStatusStreamEvent,
   formatGeneratedBranchName,
   buildTemporaryWorktreeBranchName,
+  flattenTemporaryWorktreeBranchName,
   isTemporaryWorktreeBranch,
   normalizeGitRemoteUrl,
   parseGitHubRepositoryNameWithOwnerFromRemoteUrl,
@@ -206,6 +207,19 @@ describe("isTemporaryWorktreeBranch", () => {
     ).toBe(false);
   });
 
+  it("matches the flat fallback used when a plain t3code branch exists", () => {
+    const flat = flattenTemporaryWorktreeBranchName(`${WORKTREE_BRANCH_PREFIX}/deadbeef`);
+    expect(flat).toBe(`${WORKTREE_BRANCH_PREFIX}-deadbeef`);
+    expect(isTemporaryWorktreeBranch(flat)).toBe(true);
+    expect(isTemporaryWorktreeBranch(`${WORKTREE_BRANCH_PREFIX}-deadbeef-extra`)).toBe(false);
+    expect(isTemporaryWorktreeBranch(`${WORKTREE_BRANCH_PREFIX}-feature`)).toBe(false);
+    expect(
+      flattenTemporaryWorktreeBranchName(
+        `${WORKTREE_BRANCH_PREFIX}/f4ae4e0e-f971-4d48-b4f2-9cf0aa54ab12`,
+      ),
+    ).toBe(`${WORKTREE_BRANCH_PREFIX}-f4ae4e0e`);
+  });
+
   it("rejects non-temporary refName names", () => {
     expect(isTemporaryWorktreeBranch(`${WORKTREE_BRANCH_PREFIX}/feature/demo`)).toBe(false);
     expect(isTemporaryWorktreeBranch("main")).toBe(false);

packages/shared/src/git.ts

@@ -16,8 +16,9 @@ export const WORKTREE_BRANCH_PREFIX = "t3code";
 // via Crypto.randomUUID() (always RFC 4122 v4), so the matcher also accepts exactly
 // that shape — version nibble `4`, variant nibble `[89ab]` — to keep those threads
 // eligible for branch regeneration without loosening beyond what was ever generated.
+// `t3code-<8 hex>` is the fallback when a plain `t3code` branch blocks the namespace.
 const TEMP_WORKTREE_BRANCH_PATTERN = new RegExp(
-  `^${WORKTREE_BRANCH_PREFIX}\\/(?:[0-9a-f]{8}|[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12})$`,
+  `^${WORKTREE_BRANCH_PREFIX}(?:-[0-9a-f]{8}$|\\/(?:[0-9a-f]{8}|[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12})$)`,
 );
 
 /**
@@ -123,6 +124,19 @@ export function buildTemporaryWorktreeBranchName(
   return `${WORKTREE_BRANCH_PREFIX}/${token}`;
 }
 
+/**
+ * Git stores refs as paths, so a plain `t3code` branch makes every `t3code/<hex>`
+ * ref impossible. This moves a temporary name to the flat `t3code-<hex>` sibling.
+ */
+export function flattenTemporaryWorktreeBranchName(refName: string): string {
+  // Keep only the canonical 8-hex token so legacy UUID names stay recognizable.
+  const token = refName
+    .trim()
+    .toLowerCase()
+    .slice(WORKTREE_BRANCH_PREFIX.length + 1, WORKTREE_BRANCH_PREFIX.length + 9);
+  return `${WORKTREE_BRANCH_PREFIX}-${token}`;
+}
+
 export function isTemporaryWorktreeBranch(refName: string): boolean {
   return TEMP_WORKTREE_BRANCH_PATTERN.test(refName.trim().toLowerCase());
 }