fix(spawn): stop sending branch on spawn, render API errors, wire worker name

[ashish921998]

What

Re-lands the spawn-modal fixes from the closed redesign branch (#156) onto main, revives the renderer test suite that would have caught them, and fixes the remoteless-repo spawn failure found in post-merge QA.

Spawn modal (3 bugs)

1. Every spawn 409'd when "Based on: Branch" was left at its default. createTask sent branch: "main", but the API's branch field names the session's new worktree branch — sending an already-checked-out branch makes the daemon reply BRANCH_CHECKED_OUT_ELSEWHERE. The field is gone from the request; the "Based on" pane is now informational (workers branch off the project's default branch in a fresh worktree).
2. Spawn failures rendered as [object Object]. openapi-fetch resolves non-2xx responses to a plain {code, error, message} envelope, not an Error. New apiErrorMessage unwraps it, so the user sees e.g. main is checked out at /home/me/my-app (BRANCH_CHECKED_OUT_ELSEWHERE).
3. The "Worker name" field did nothing. After a successful spawn, the name is now sent as a best-effort PATCH rename (a failed rename must not surface as a failed spawn — the worker is already running; retrying would spawn a duplicate).

Remoteless-repo spawn fix (backend)

Found in post-merge QA: a registered repo with no git remote failed every spawn with BRANCH_NOT_FETCHED — an error that names the new session branch and suggests git fetch, impossible without a remote. The workspace layer resolved the base for a new session branch only via origin/<defaultBranch>; refs/heads/<defaultBranch> now follows it in the candidate list (remote-tracking still wins when present). Re-landed from the redesign archive with its integration test, and verified live against the repo that failed QA.

Test-suite revival

vitest run only auto-loads vite.config.ts/vitest.config.ts — Forge's per-target vite.*.config.ts files are invisible to it, so the test block in vite.renderer.config.ts (jsdom + setup file) was dead config and 7 of 9 suite files failed with window is not defined. A one-line vitest.config.ts re-exports the renderer config.

Knock-on fixes from actually loading that config:

• vite.renderer.config.ts imports defineConfig from vitest/config so its test key typechecks.
• routeTree.gen.ts + the session route file are regenerated by the pinned @tanstack/router-plugin (the checked-in tree predated the installed plugin version; its route-ID drift caused 3 of main's 7 typecheck errors, and any npm start would regenerate these files anyway).
• App.test.tsx wraps App in TooltipProvider, mirroring routes/__root.tsx.

Verification

• Frontend: 9/9 test files, 99/99 tests pass (main: 2/9 files runnable). New tests pin all three fixes: no-branch spawn body, rename round-trip, envelope message (and no [object Object]).
• Backend: full go test ./... green incl. TestWorkspaceIntegrationCreateInRemotelessRepo; golangci-lint 0 issues on touched packages.
• Live: a plain git init repo (no remote) that failed spawn on main spawns successfully with this branch's daemon.
• npm run typecheck: 7 errors → 3. The 3 survivors (forge.config.ts notarize/maker types, update-electron-app call signature) predate this branch and are untouched.

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

This PR fixes three spawn-modal bugs (409 on branch field, [object Object] error rendering, and the no-op worker name field), revives the renderer test suite under vitest, and extends the git worktree adapter to fall back to refs/heads/<defaultBranch> for remoteless repos.

• Spawn fixes: branch is removed from the POST body; errors are now unwrapped through apiErrorMessage; a best-effort PATCH rename runs after a successful spawn and silently falls back to the prompt as title if the rename fails.
• Test revival: vitest.config.ts re-exports the renderer config so its jsdom environment and setup file apply during test runs; three new integration tests cover no-branch spawn, rename round-trip, and error-envelope rendering.
• Backend: baseRefCandidates appends refs/heads/<defaultBranch> after origin/<defaultBranch> for unqualified default branches, allowing worktree creation in repos without a configured remote.

Confidence Score: 5/5

Safe to merge — all three spawn-modal bugs are cleanly fixed, the backend fallback is guarded by both a unit test and a new integration test, and the test revival brings 99/99 tests passing.

Every changed path has direct test coverage: the no-branch POST body, rename round-trip, and error-envelope rendering are each pinned by a new test. The backend candidate-list change is covered by an updated unit test and a new end-to-end integration test. The vitest config fix is structural (re-export) with no logic of its own. No previously-flagged issues are reintroduced.

No files require special attention.

Important Files Changed

Filename	Overview
frontend/src/renderer/App.tsx	Adds apiErrorMessage helper, removes branch from POST body, adds best-effort PATCH rename; logic is correct and well-commented.
frontend/src/renderer/components/SpawnWorkerModal.tsx	Removes branch state and SelectControl in favour of informational text; wires name field into onCreateTask; clean removal.
frontend/src/renderer/App.test.tsx	Adds patchMock, TooltipProvider wrapper, and three new targeted tests (no-branch POST, rename round-trip, error envelope); coverage is solid.
backend/internal/adapters/workspace/gitworktree/commands.go	Appends refs/heads/ fallback for remoteless repos; guarded by unit and integration tests.
backend/internal/adapters/workspace/gitworktree/workspace_integration_test.go	New TestWorkspaceIntegrationCreateInRemotelessRepo exercises the regression fix end-to-end against real git.
frontend/vitest.config.ts	One-liner re-export of vite.renderer.config.ts; correctly makes the jsdom test environment visible to vitest.
frontend/vite.renderer.config.ts	defineConfig import changed from vite to vitest/config for proper test block typechecking; functionally equivalent for production builds.
frontend/src/renderer/routeTree.gen.ts	Auto-regenerated by @tanstack/router-plugin; module augmentation added, WithChildren suffix removed; machine-generated, no manual review needed.
frontend/src/renderer/routes/workspaces.$workspaceId_.sessions.$sessionId.tsx	Route ID corrected to match the generated tree.
backend/internal/adapters/workspace/gitworktree/workspace_test.go	TestBaseRefCandidates updated to expect the new refs/heads/ entry.

Sequence Diagram

sequenceDiagram
    participant UI as SpawnWorkerModal
    participant App as App.createTask
    participant API as Daemon API

    UI->>App: "onCreateTask({ projectId, prompt, name?, harness })"
    Note over App: No branch field sent
    App->>API: POST /api/v1/sessions
    alt 2xx response
        API-->>App: "{ session: { id, ... } }"
        opt name provided
            App->>API: "PATCH /api/v1/sessions/{sessionId}"
            alt rename succeeds
                API-->>App: "{ displayName }"
                Note over App: title = displayName
            else rename fails
                Note over App: title = prompt (silent fallback)
            end
        end
        App-->>UI: resolved, modal closes
    else non-2xx
        API-->>App: "{ error: { code, message } }"
        Note over App: apiErrorMessage unwraps envelope
        App-->>UI: throw Error(message + code)
        UI->>UI: setError shown in modal
    end

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_{Reviews (2): Last reviewed commit: "fix(gitworktree): base new session branc..." | Re-trigger Greptile}

[greptile-apps]

Rename errors are silently swallowed with no user feedback

When the PATCH rename fails (network error, 4xx/5xx from the daemon), renamed.data?.displayName is undefined, displayName stays undefined, and the session title silently falls back to the prompt text. The user sees the modal close and the session appear, but with a different name than they typed — there's no indication the rename failed. The comment says this is intentional, but at minimum a console.warn would help diagnose the situation. If the UX contract is "rename failure = silently use the prompt as title", a brief inline note in the UI (or at least a console.warn) would make the silent fallback discoverable.

[greptile-apps]

Rename-failure path is untested

The new "renames the spawned worker when a name is given" test covers the happy path (PATCH succeeds, displayName returned). There is no test for the case where patchMock resolves with { error: ... } or { data: undefined } — i.e., the best-effort silent fallback described in the App.tsx comment. Without a test, it's easy for a future refactor to accidentally surface the rename error to the user (breaking the spawn) or show the wrong title without anyone noticing.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!