feat(worktrees): create, open and remove git worktrees of a case

CLAUDE.md

@@ -231,6 +231,8 @@ Codeman is a Claude Code session manager with web interface and autonomous Ralph
 
 **Clone a repository as a case** (issue #236, Add Case → **Clone Repo**): `POST /api/cases/clone` clones synchronously into the caller's case space (bounded by `GIT_CLONE_TIMEOUT_MS`, no job store); `POST /api/cases/clone-preflight` checks anonymous cloneability and lists refs. Core in `src/git-clone.ts`. ⚠️ **The URL is a code-execution surface**: refuse every `::` form and a leading `-`, spawn only argv arrays with `--` before operands. ⚠️ Stay non-interactive (`gitNonInteractiveEnv()`) or the open request hangs; never collect credentials, refuse `user:password@` URLs. ⚠️ Timeout kills the process GROUP, remove the destination only if this attempt created it, and repo contents win over scaffolding (existing `CLAUDE.md` kept, hooks merged, repo `.claude/settings*` warned about). → [architecture-invariants#clone-a-repository-as-a-case](docs/architecture-invariants.md#clone-a-repository-as-a-case)
 
+**Git worktrees of a case** (case picker → **Git worktrees…**; `src/git-worktrees.ts`, `routes/worktree-routes.ts`): a local repository case keeps worktrees at `<repo>/.claude/worktrees/<name>` on `worktree-<name>`, Claude Code's own `--worktree` layout. ⚠️ Only that managed path is ever created or removed, every component `lstat`ed and realpath-checked (a symlinked `.claude` is refused). ⚠️ git never runs for a Docker or remote case, nor at or inside a Docker workspace (`worktree add` runs hooks and filters on the host). ⚠️ Remove is `git worktree remove` WITHOUT `--force`, refused while a live session is inside; branch delete is `-d`, never `-D`. ⚠️ Sessions start through the existing create paths (quick-start `worktree`, or `POST /api/sessions` `workingDir`), never a new spawn path. → [architecture-invariants#git-worktrees-of-a-case](docs/architecture-invariants.md#git-worktrees-of-a-case)
+
 **Cross-session search**: `GET /api/search` federates an in-memory search over session metadata, run-summary events, and attachment-history entries. The pure core `searchSources()` does substring matching with hard per-type caps: **no regex (so no ReDoS) and no filesystem reads (so no traversal)**. The server-private `externalPath` is never read. PAST sessions (#261) come from `session-history-index.ts`, a capped snapshot of the unified list filled **outside** the request path (`/api/sessions/unified` publishes it; a stale one is rebuilt fire-and-forget), that indirection is what keeps the no-fs property. ⚠️ The snapshot is stored UNSCOPED with a per-row owner and MUST be re-filtered through `canAccessOwned()` on read; history rows carry `jumpTo.kind:'resume-session'`, since a closed session has no tab to select. → [architecture-invariants#cross-session-search](docs/architecture-invariants.md#cross-session-search)
 
 **Web tabs** (dashboard URLs as tabs): a saved URL renders as a tab beside sessions, **NOT a `SessionMode`**, and is proxied through Codeman's own origin (`/webview/<cap>/...`). ⚠️ The proxy is NOT an API surface: its capability-based auth exemption stays fenced to safe methods and non-route paths (`test/webview-auth-exemption.test.ts`). ⚠️ Iframes omit `allow-same-origin` unless `trusted`, and `Authorization`/`codeman_session` are stripped upstream in both modes. ⚠️ **Egress guard**: link-local and cloud-metadata targets are refused at save time, by a sync hostname check at each connect (IP literals skip DNS), AND on the resolved address (`webview-egress.ts`); use the `undici` package's own `fetch` + `Agent`, never Node's global fetch. ⚠️ Loopback links in agent output auto-open as proxied web tabs (`openLinkThroughWebTabIfLoopback`), but never auto-route `*.localhost` (prompt-injectable DNS). Capabilities are revoked on logout (`revokeOwner`). → [architecture-invariants#web-tabs](docs/architecture-invariants.md#web-tabs), `docs/web-tabs.md`

docs/api-reference.md

@@ -1011,6 +1011,42 @@ Both routes accept two optional query parameters, which the UI sends from its pe
 
 Lists are capped (300 files and 50 commits per repository) while the counts stay exact. A branch with no upstream reports the commits no remote has (`HEAD --not --remotes`); a repository with no remote reports `unpushedCount: 0`, since there is nothing to push to. Concurrent polls of one folder share a single git invocation; `?fresh=1` (what the panel's Refresh button and opening the panel send) skips the short-lived caches, though it still joins a computation already running.
 
+## Git worktrees of a case
+
+A local case whose folder is the top of a git repository can keep **worktrees** at `<case>/.claude/worktrees/<name>`, each on its own branch, so several agents on one repository never share a checkout. This is the layout Claude Code's own `claude --worktree <name>` uses (branch `worktree-<name>`), so either tool finds the other's worktrees. Remote (SSH) and Docker cases are refused with `400 INVALID_INPUT` before git runs, and so is a local case whose folder is at or inside a Docker case workspace: `git worktree add` runs the repository's post-checkout hook and checkout filters on this machine, and a container can write there. A case folder that is not a repository, is a bare repository, or sits below the repository's top level is `400` too. The case resolves the way quick-start resolves it (a linked case is admin-only in multi-user mode, everything else is the caller's own case space; another user's case is `404`), and a case folder on a mount that does not answer is `422 OPERATION_FAILED`, never `404`.
+
+`GET /api/cases/:name/worktrees` lists `git worktree list` for the case's repository:
+
+```json
+{
+  "caseName": "myrepo",
+  "repoRoot": "/home/me/codeman-cases/myrepo",
+  "worktreesDir": "/home/me/codeman-cases/myrepo/.claude/worktrees",
+  "truncated": false,
+  "worktrees": [
+    { "path": "/home/me/codeman-cases/myrepo", "head": "6910cb15…", "branch": "main", "detached": false, "bare": false,
+      "locked": false, "prunable": false, "main": true, "isCase": true, "managed": false, "sessionCount": 0, "sessions": [] },
+    { "path": "/home/me/codeman-cases/myrepo/.claude/worktrees/fix-login", "branch": "worktree-fix-login",
+      "main": false, "isCase": false, "managed": true, "name": "fix-login",
+      "sessionCount": 1, "sessions": [{ "id": "2a568379-…", "name": "w1-fix-login" }] }
+  ]
+}
+```
+
+`managed` is `true` only for `<repoRoot>/.claude/worktrees/<name>`: those are the ones Codeman starts sessions in and removes; any other worktree of the repository is listed for information. `sessionCount` counts live sessions of every owner running in that worktree (a session belongs to the deepest worktree holding its folder), `sessions` lists the ones the caller may see. `lockReason`/`prunableReason` appear when git reports them.
+
+`POST /api/cases/:name/worktrees` with `{ name, branch?, base? }` creates one (`201`, `{ worktree: { name, path, branch, base, head, excludeAdded, warnings } }`):
+
+- `name`: 1 to 64 characters of `A-Z a-z 0-9 . _ -`, starting with a letter or digit, no `..`, not ending in `.` or `.lock`. `400` otherwise.
+- `branch`: the NEW branch, default `worktree-<name>`. Letters, digits, `.`, `_`, `-`, `/`, then `git check-ref-format --branch` must accept it unchanged. An existing branch is `409 ALREADY_EXISTS` (never reset), and so is a name whose folder already exists.
+- `base`: where the branch starts, default `HEAD` (the case's current commit): a branch, tag or commit, resolved before anything is written (`400` when it is not a commit, which includes an empty repository).
+- `excludeAdded` lists the lines appended to the repository's local `info/exclude` (in the real common git dir, never a tracked `.gitignore`) when git did not already ignore them: `/.claude/worktrees/`, so the main checkout does not show the worktrees as untracked, `/.claude/settings.local.json`, the hooks file Codeman writes for every claude session, which would otherwise make `git worktree remove` refuse, and the agent skill copy (`/.claude/skills/codeman/`, `/.agents/skills/codeman/`: every skills folder the CLI registry names) that sessions get while `agentSkillEnabled` is on, for the same reason.
+- A symlinked `.claude` or `.claude/worktrees` directory is refused (`400`): a repository cannot redirect the worktree outside itself.
+
+`DELETE /api/cases/:name/worktrees/:worktree[?deleteBranch=true]` removes a managed worktree with `git worktree remove` **without `--force`**: git refuses a worktree with modified or untracked files (or a locked one), and that refusal is the answer, `409 CONFLICT` with git's own words in `error`. A live session at or inside the worktree is `409` as well. With `deleteBranch=true` the branch is deleted with `git branch -d`, never `-D`, so an unmerged branch is kept: the response is still `200`, with `branchDeleted: false` and git's reason in `branchError`. Response: `{ removed: { name, path, branch, branchDeleted, branchError? } }`. A folder git does not list as a worktree of this repository, or a symlink in its place, is `404`/`400`. A managed worktree whose folder is gone (deleted by hand; the list reports it `prunable`) is still removable: git then only drops its record, which is what frees the name for a new worktree. A session never starts in one.
+
+**Starting a session in a worktree** goes through the normal create paths: `POST /api/quick-start` takes `worktree: "<name>"` next to `caseName` and runs the session (and the hooks, the agent skill and `modelOverride`) in the worktree folder; the response adds `worktree` and `workingDir`. It is refused for remote and Docker cases (`400`), for a worktree that is not a registered, managed one (`404`), and for a case that does not exist (`404`: a worktree launch never scaffolds a case). `POST /api/sessions` takes the worktree path as `workingDir` like any other folder.
+
 ## CLI management
 
 Read and write the CLI registry (`docs/cli-registry.md`). Every **write** route answers `403 FORBIDDEN` while `cliManagementEnabled` is off (the default), and for a non-admin in multi-user mode. A write that would overwrite a `clis.json` which does not parse, or which has group/world permission bits, is refused with `409 CONFLICT` and a message naming the fix; the file is left untouched.

docs/architecture-invariants.md

@@ -448,6 +448,20 @@ Tests: `test/git-clone.test.ts` (pure half exhaustively, plus REAL git against a
 
 Further detail: the synchronous clone request is bounded by `GIT_CLONE_TIMEOUT_MS`.
 
+### Git worktrees of a case
+
+**Git worktrees** (case picker → **Git worktrees…**, the phone case sheet's **Worktrees**, Close Session's **Kill & remove worktree**): a LOCAL case whose folder is the top of a git repository keeps worktrees at `<repo>/.claude/worktrees/<name>` on a new branch (default `worktree-<name>`), so parallel agents each get their own checkout instead of sharing the case folder. That is Claude Code's own `--worktree` layout (measured in 2.1.296: same path, branch `worktree-<name>`, names of `[A-Za-z0-9._-]`, at most 64), and Codeman's names are a strict subset of Claude's. Core in `src/git-worktrees.ts` (pure name/branch gates, `worktree list --porcelain` parsing, exclude text; IO behind an injectable runner); routes in `routes/worktree-routes.ts` (`GET`/`POST /api/cases/:name/worktrees`, `DELETE /api/cases/:name/worktrees/:worktree`).
+
+- ⚠️ **Only `<repo>/.claude/worktrees/<valid-name>` is ever created or removed.** Every component is `lstat`ed (a symlinked `.claude`, `worktrees` or worktree folder is refused, never followed) and the real path must equal the lexical one, so a repository cannot redirect a create or remove outside itself; removal also requires git to list the folder as a worktree of THIS repository. A worktree anywhere else is listed read-only (`managed: false`). A managed worktree whose folder is GONE stays removable (`resolveManagedWorktree({ allowMissing })`, removal only, never a session start: git lists it at exactly the managed path, no component on the way is a symlink, and `git worktree remove` then only drops git's record), since otherwise its name could never be used again.
+- ⚠️ **git never runs for a case at or inside a Docker case workspace** (or whose common git dir is there), and Docker and remote cases are refused with a 400 before any git, the same rule as the git status indicator: `git worktree add` runs the repository's post-checkout hook and checkout filters ON THE HOST. That is acceptable for a local case, where the user's agent already runs code.
+- ⚠️ **Removal is `git worktree remove` WITHOUT `--force`**, refused (409) while any live session (any owner) runs at or inside the worktree, and git's own refusal (modified or untracked files, a lock) is the answer, shown through `textContent`. The optional branch delete is `git branch -d`, never `-D`: an unmerged branch survives and the response says why (`branchError`).
+- ⚠️ **The main checkout must not see the worktrees.** When `git check-ignore` says they are not ignored, `/.claude/worktrees/` is appended to the repository's LOCAL `<common git dir>/info/exclude` (never a tracked `.gitignore`), and so is `/.claude/settings.local.json`: Codeman writes its hooks there for every claude session, and an untracked copy in a worktree would make `git worktree remove` refuse forever (Claude Code covers that file with the global excludes file, which a machine may not have). The agent skill copy (`<skills dir>/codeman/`, injected while `agentSkillEnabled` is on) gets a line too, for every skills folder the registry names (`capabilities.agentSkillDir`, passed in by the route as data). A symlinked `info` dir or `exclude` file is reported, never written through.
+- **Names are gated before git**: charset and length (Zod and `worktreeNameError()`), then `git check-ref-format --branch`, whose output must EQUAL the input (`--branch` expands `@{-1}`, which the charset gate already refuses). The base is a resolved commit (`rev-parse --verify <base>^{commit}`), passed after `--` with `--no-track`; an existing branch is refused (`-b`, never `-B`, which would reset it). Create and remove are serialized per repository.
+- **Sessions start through the EXISTING create paths**, never a new spawn path: `POST /api/quick-start` with `worktree` (resolved with the same guards; hooks, the agent skill, the model override and the session all target the worktree, and a case that does not exist is a 404, never a scaffold), or `POST /api/sessions` with the worktree as `workingDir` (what the Run button uses for claude and shell). The frontend launches through `run({ worktree })` with a temporary `_runMode` swap, tabs named `w<n>-<worktree>`.
+- The unified session list names a live session's worktree from its folder layout (`worktreeFromPath`), so a codex or shell session gets the worktree pill before (or without) a transcript record.
+
+Tests: `test/git-worktrees.test.ts` (pure half, then REAL git: create, exclude, symlink guards, dirty/live/locked refusals, `branch -d`), `test/routes/worktree-routes.test.ts` (real repository through the routes and quick-start, Docker/remote/ownership refusals), `test/worktree-ui.test.ts`, `test/worktree-modal-i18n.test.ts`.
+
 ### Ultracode and workflow-run visualization
 
 **Ultracode / Workflow-run visualization** (opt-in `showUltracodeAgents`, default OFF; released 1.1.2): the Workflow tool ("ultracode") writes a COMPLETION artifact per run at `~/.claude/projects/<projHash>/<sessionUuid>/workflows/wf_*.json` (written only at run end); LIVE in-flight runs exist only as transcript dirs at `…/subagents/workflows/wf_<id>/` (journal.jsonl + `agent-*.jsonl`). `workflow-run-watcher.ts` (STANDALONE — deliberately never imports/touches `subagent-watcher.ts`; separate singleton, though it independently reads the same `subagents/workflows/` tree) scans BOTH sources via periodic poll + per-directory chokidar watchers with per-source mtime skip (LRU agentStatCache + journalCache), synthesizing ACTIVE runs (live per-agent tokens/tools/state from transcripts, title/phases from the workflow script) until the completion `wf_*.json` appears and supersedes, and broadcasts SSE `workflow:run_discovered`/`run_updated`/`run_removed`. The watcher is started when **either** `showUltracodeAgents` **or** `ultracodeFloatingWindows` is on (`server.ts` `isWorkflowAgentTrackingEnabled()` returns `(showUltracodeAgents ?? false) || (ultracodeFloatingWindows ?? false)`). Served via `GET /api/workflows` (optional `?minutes=` filter) and `GET /api/workflows/:runId`. Frontend `ultracode-panel.js` renders a docked master-detail view (LEFT: runs + phases; RIGHT: per-agent tokens + tool-calls; click an agent card → its live transcript via client-side `agentId` join). **Additionally**, `ultracode-windows.js` auto-pops a draggable **floating window per active run** (gated on a **DEDICATED** `ultracodeFloatingWindows` toggle, default OFF — independent of the dock panel's `showUltracodeAgents`; see `_ultracodeFloatingEnabled()`), connected by a glowing line to the originating session tab (resolved by `session.claudeSessionId === run.sessionUuid`) — same line idiom as subagent windows, drawn into the shared `#connectionLines` SVG from the tail of `_updateConnectionLinesImmediate`. The window auto-closes ~8s after its run finishes; explicit dismissals are remembered. Clicking an agent card opens an **in-page** connected transcript window (not a browser popup); both run and transcript windows minimize **into** the originating session tab as a merged `ULTRA` badge (🧬 runs / 📄 transcripts) with a restore/dismiss dropdown — minimized runs are skipped by auto-pop. Gesture beta: floating subagent/ultracode windows are pinch-draggable (a `window` grab kind in `entry.ts`). Types: `src/types/workflow-run.ts`. Config: `src/config/workflow-config.ts`.

docs/wiki/Core-Concepts.md

@@ -46,7 +46,8 @@ case. Each has a stable id, and that id is what the API, the wait primitives, an
 event use.
 
 Several sessions can share one case. That is the normal way to parallelize: three workers
-in the same repo, three tabs, one case.
+in the same repo, three tabs, one case. They then also share one folder; when the workers
+edit and commit in parallel, give each its own checkout with [Git Worktrees](Git-Worktrees).
 
 A session carries state the case does not: