docs: standardize isolated LLM worktrees (#38)

.gitignore

@@ -8,3 +8,4 @@ gitea-mcp*.json
 !gitea-mcp.example.json
 .vscode/
 graphify-out/
+branches/

docs/llm-workflow-runbooks.md

@@ -161,6 +161,62 @@ Legacy environment-only setups keep working unchanged until migrated.
 Each runbook names the **profile role** it runs under, the steps, and a safe
 prompt. Confirm the active profile first (`gitea_get_profile` / `gitea_whoami`).
 
+## Branch worktree isolation
+
+All LLM implementation and review work happens in an isolated branch worktree
+under `branches/`. The main repository checkout is an orchestration checkout:
+use it for status checks, issue creation/claiming, and creating worktrees, but
+do not edit tracked repository files there.
+
+Branch folders are ignored by git via `branches/`, so dirty work in one issue
+does not block starting an unrelated issue in a separate branch folder. No LLM
+may edit another issue's branch folder unless explicitly assigned to that issue.
+No LLM may clean another issue's branch folder unless the PR is merged or closed
+and cleanup is explicitly part of the task.
+
+Implementation work and review work must use separate branch folders. For
+example, an implementation branch might live under
+`branches/fix-issue-123-example`, while a review branch for the resulting PR
+uses its own folder.
+
+Issue creation and claiming may happen from the orchestration checkout:
+
+1. Create or identify the tracking issue.
+2. Claim it with `status:in-progress`.
+3. Create the issue branch worktree.
+4. `cd` into the branch worktree and perform all file edits there.
+
+Preferred helper:
+
+```bash
+scripts/worktree-start fix/issue-123-example
+cd branches/fix-issue-123-example
+```
+
+Because `venv/` is ignored and not copied into new worktrees, run checks with a
+known Python interpreter. Either create a venv inside the branch folder, or use
+the orchestration checkout's venv by explicit path.
+
+Equivalent manual commands:
+
+```bash
+git fetch prgs --prune
+git worktree add -b fix/issue-123-example branches/fix-issue-123-example prgs/master
+cd branches/fix-issue-123-example
+```
+
+For review work, create a separate review worktree/folder instead of reusing the
+author's implementation folder.
+
+Cleanup is explicit and only after merge or close:
+
+```bash
+cd <main-repo>
+git fetch prgs --prune
+git worktree remove branches/fix-issue-123-example
+git branch -d fix/issue-123-example
+```
+
 ### Create an issue / child issues
 
 - **Profile:** issue-manager or author (any profile allowed to create issues).
@@ -172,9 +228,10 @@ prompt. Confirm the active profile first (`gitea_get_profile` / `gitea_whoami`).
 ### Implement an issue and open a PR
 
 - **Profile:** author.
-- **Steps:** claim the issue (`status:in-progress`); branch from latest
-  `master` (`feat/issue-<n>-...` / `fix/...` / `docs/...`); implement narrowly;
-  add/update tests if behavior changes; run the full suite; commit with an
+- **Steps:** claim the issue (`status:in-progress`); create an isolated branch
+  worktree from latest `master` under `branches/` (`feat/issue-<n>-...` /
+  `fix/...` / `docs/...`); `cd` into that worktree; implement narrowly; add or
+  update tests if behavior changes; run the full suite; commit with an
   issue-linked message; open a PR to `master`. **Do not** review or merge your
   own PR.
 - **Prompt:** `Use an author profile to implement issue #N and open a PR to

scripts/worktree-start

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+usage() {
+  cat <<'EOF'
+usage: scripts/worktree-start [--dry-run] <branch-name> [start-ref]
+
+Create an issue-specific git worktree under branches/<branch-name-with-slashes-replaced>.
+
+Examples:
+  scripts/worktree-start fix/issue-123-example
+  scripts/worktree-start --dry-run review/pr-123-scope-check prgs/master
+EOF
+}
+
+dry_run=0
+if [[ "${1:-}" == "--dry-run" ]]; then
+  dry_run=1
+  shift
+fi
+
+if [[ $# -lt 1 || $# -gt 2 ]]; then
+  usage >&2
+  exit 2
+fi
+
+branch="$1"
+start_ref="${2:-prgs/master}"
+
+script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+repo_root="$(cd "$script_dir/.." && pwd)"
+worktree_name="${branch//\//-}"
+worktree_path="$repo_root/branches/$worktree_name"
+
+if [[ -e "$worktree_path" ]]; then
+  cat >&2 <<EOF
+Refusing to reuse existing branch worktree:
+  $worktree_path
+
+Inspect it manually. Do not overwrite or clean another issue's branch folder
+unless that issue is explicitly assigned and cleanup is part of the task.
+EOF
+  exit 1
+fi
+
+if [[ "$dry_run" -eq 1 ]]; then
+  printf 'repo: %s\n' "$repo_root"
+  printf 'branch: %s\n' "$branch"
+  printf 'start-ref: %s\n' "$start_ref"
+  printf 'worktree: %s\n' "$worktree_path"
+  printf 'commands:\n'
+  printf '  git -C %q fetch prgs --prune\n' "$repo_root"
+  printf '  git -C %q worktree add -b %q %q %q\n' \
+    "$repo_root" "$branch" "$worktree_path" "$start_ref"
+  exit 0
+fi
+
+git -C "$repo_root" fetch prgs --prune
+git -C "$repo_root" worktree add -b "$branch" "$worktree_path" "$start_ref"
+printf '%s\n' "$worktree_path"