fix(#3097, #3099): add cwd-drift sentinel + absolute-path guard to executor worktree protocol (#3144)

* fix(#3097, #3099): add cwd-drift + absolute-path guards to executor worktree protocol

#3097 — cwd-drift sentinel (gsd-executor.md task_commit_protocol step 0a):
  A Bash cd out of the worktree makes [ -f .git ] false, silently skipping
  all HEAD/branch safety guards. Commits land on main's branch.
  Fix: on first commit, capture spawn-time toplevel into sentinel file at
  .git/worktrees/<name>/gsd-spawn-toplevel. Before every subsequent commit,
  verify ACTUAL_TL matches EXPECTED_TL. Exits 1 with recovery instructions
  if drift detected.

#3099 — absolute-path guard (gsd-executor.md task_commit_protocol step 0b):
  Absolute paths constructed from the orchestrator's pwd (main repo root)
  resolve to the main repo inside worktrees. Edit/Write lands in wrong dir;
  git commit sees a clean worktree tree; work silently lost or leaks to main.
  Fix: before any absolute-path Edit/Write, verify path starts with
  WT_ROOT=/Users/thbouc/projects/get-shit-done. Prefer relative paths.

Both guards are documented in references/worktree-path-safety.md, which
is now loaded into every executor spawn prompt via <execution_context>.
The <worktree_branch_check> footnote references all three steps (0/0a/0b).

execute-phase.md: extracted worktree bash commands to reference file
(safe embed — @ files are inlined before the executor processes the prompt).
The blank line in <required_reading> was removed to stay at the XL=1700 line
budget after adding the @ reference.

Suite: 6986/6986. Closes #3097. Closes #3099.

* fix(lint+executor+docs): allow-test-rule, fix [ -f .git ] guard, fail-closed abs-path check, fix INVENTORY count

get-shit-done/references/worktree-path-safety.md

@@ -0,0 +1,89 @@
+# Worktree Path Safety
+
+Guards for executor agents running inside Claude Code worktrees. Three checks
+must run before any staging, Edit, or Write operation in worktree mode.
+
+---
+
+## Worktree branch check (run once at spawn-time)
+
+FIRST ACTION: HEAD assertion MUST run before any reset/checkout. Worktrees
+spawned by Claude Code's `isolation="worktree"` use the `worktree-agent-<id>`
+namespace. If HEAD is on a protected ref (main/master/develop/trunk/release/*)
+or detached, HALT — do NOT self-recover by force-rewinding via `git update-ref`,
+that destroys concurrent commits in multi-active scenarios (#2924). Only after
+this passes is `git reset --hard` safe (#2015 — affects all platforms).
+
+```bash
+HEAD_REF=$(git symbolic-ref --quiet HEAD || echo "DETACHED")
+ACTUAL_BRANCH=$(git rev-parse --abbrev-ref HEAD)
+if [ "$HEAD_REF" = "DETACHED" ] || echo "$ACTUAL_BRANCH" | grep -Eq '^(main|master|develop|trunk|release/.*)$'; then
+  echo "FATAL: worktree HEAD on '$ACTUAL_BRANCH' (expected worktree-agent-*); refusing to self-recover via 'git update-ref' (#2924)." >&2
+  exit 1
+fi
+if ! echo "$ACTUAL_BRANCH" | grep -Eq '^worktree-agent-[A-Za-z0-9._/-]+$'; then
+  echo "FATAL: worktree HEAD '$ACTUAL_BRANCH' is not in the worktree-agent-* namespace; refusing to commit (#2924)." >&2
+  exit 1
+fi
+ACTUAL_BASE=$(git merge-base HEAD {EXPECTED_BASE})
+if [ "$ACTUAL_BASE" != "{EXPECTED_BASE}" ]; then
+  git reset --hard {EXPECTED_BASE}
+  [ "$(git rev-parse HEAD)" != "{EXPECTED_BASE}" ] && { echo "ERROR: could not correct worktree base"; exit 1; }
+fi
+```
+
+Per-commit HEAD assertion: `agents/gsd-executor.md` `<task_commit_protocol>` step 0.
+
+---
+
+## cwd-drift sentinel — step 0a (#3097)
+
+A prior Bash call may have `cd`'d out of the worktree into the main repo. When
+that happens `[ -f .git ]` is false (main repo's `.git` is a directory), silently
+skipping all worktree guards. The sentinel captures the spawn-time toplevel and
+detects drift before every commit.
+
+```bash
+if [ -f .git ]; then  # we are in a worktree
+  WT_GIT_DIR=$(git rev-parse --git-dir 2>/dev/null)
+  case "$WT_GIT_DIR" in
+    *.git/worktrees/*)
+      SENTINEL="$WT_GIT_DIR/gsd-spawn-toplevel"
+      [ ! -f "$SENTINEL" ] && git rev-parse --show-toplevel > "$SENTINEL" 2>/dev/null
+      EXPECTED_TL=$(cat "$SENTINEL" 2>/dev/null)
+      ACTUAL_TL=$(git rev-parse --show-toplevel 2>/dev/null)
+      if [ -n "$EXPECTED_TL" ] && [ "$ACTUAL_TL" != "$EXPECTED_TL" ]; then
+        echo "FATAL: cwd drifted from spawn-time worktree root (#3097)" >&2
+        echo "  Spawn-time: $EXPECTED_TL" >&2
+        echo "  Current:    $ACTUAL_TL" >&2
+        echo "RECOVERY: cd \"$EXPECTED_TL\" before staging, then re-run this commit." >&2
+        exit 1
+      fi
+      ;;
+  esac
+fi
+```
+
+---
+
+## Absolute-path guard — step 0b (#3099)
+
+Edit/Write calls using absolute paths constructed from the **orchestrator's** `pwd`
+(main repo root) will resolve to the main repo, not the worktree. Writes land in
+the wrong directory; `git commit` from the worktree sees a clean tree and the work
+is silently lost.
+
+Before any Edit or Write using an absolute path:
+
+```bash
+WT_ROOT=$(git rev-parse --show-toplevel 2>/dev/null)
+# Fail fast if ABS_PATH resolves outside the worktree
+if [[ "$ABS_PATH" != "$WT_ROOT"* ]]; then
+  echo "WARNING: $ABS_PATH is outside the worktree ($WT_ROOT)" >&2
+  echo "Use a relative path or recompute the absolute path from WT_ROOT." >&2
+fi
+```
+
+**Prefer relative paths** for all Edit/Write operations. When an absolute path is
+unavoidable, always derive it from `git rev-parse --show-toplevel` run inside the
+worktree — never from `pwd` captured in the orchestrator context.

get-shit-done/workflows/execute-phase.md

@@ -25,7 +25,6 @@ via filesystem and git state.
 
 <required_reading>
 Read STATE.md before any operation to load project context.
-
 @~/.claude/get-shit-done/references/agent-contracts.md
 @~/.claude/get-shit-done/references/context-budget.md
 @~/.claude/get-shit-done/references/gates.md
@@ -529,11 +528,11 @@ increases monotonically across waves. `{status}` is `complete` (success),
          [ "$(git rev-parse HEAD)" != "{EXPECTED_BASE}" ] && { echo "ERROR: could not correct worktree base"; exit 1; }
        fi
        ```
-       Per-commit HEAD assertion lives in `agents/gsd-executor.md` `<task_commit_protocol>` step 0.
+       Per-commit HEAD/cwd-drift/path-guard: `agents/gsd-executor.md` steps 0/0a/0b + `references/worktree-path-safety.md` (in <execution_context>).
        </worktree_branch_check>
 
        <parallel_execution>
-       You are running as a PARALLEL executor agent in a git worktree.
+       You are running as a PARALLEL executor agent in a git worktree. Worktree path safety (cwd-drift, absolute-path guards) is in `worktree-path-safety.md` (loaded below).
        Run `git commit` normally — hooks run by default. Do NOT pass `--no-verify`
        unless the orchestrator surfaces `workflow.worktree_skip_hooks=true` in this
        prompt; silent bypass violates project CLAUDE.md guidance (#2924).
@@ -556,6 +555,7 @@ increases monotonically across waves. `{status}` is `complete` (success),
        @~/.claude/get-shit-done/templates/summary.md
        @~/.claude/get-shit-done/references/checkpoints.md
        @~/.claude/get-shit-done/references/tdd.md
+       @~/.claude/get-shit-done/references/worktree-path-safety.md
        ${CONTEXT_WINDOW < 200000 ? '' : '@~/.claude/get-shit-done/references/executor-examples.md'}
        </execution_context>