/git:coworker-check

Detect another agent working in the same repo clone and warn before destructive operations that could destroy its uncommitted changes.

When to Use This Skill

Use this skill when...	Use a worktree instead when...
Session starts in a clone that may already be in use	You control the session and can create git worktree add ../<task>
About to run git stash, git reset --hard, git checkout -- .	You already know the working tree is yours alone
git status shows files you don't remember touching	Baseline + markers are already confirming you are alone

See .claude/rules/agent-coworker-detection.md for the full rationale and signal design.

Context

• Repo root: !git rev-parse --show-toplevel
• Git dir: !git rev-parse --git-dir
• Current status: !git status --porcelain=v2 --branch
• Stash count: !git stash list
• Existing markers: !find . -path './.git/.claude-session-*' -maxdepth 3

Parameters

Parse $ARGUMENTS for the mode flag. Default is --check.

Flag	Action
--check (default)	Run detection. Report verdict without writing anything.
--claim	Write a session marker and baseline snapshot for this session. Run at session start.
--release	Remove this session's marker and baseline files. Run on session exit.

Execution

Execute this detection workflow:

Step 1: Resolve mode

Inspect $ARGUMENTS. If it contains --claim, go to Step 2a. If it contains --release, go to Step 2b. Otherwise (including empty), go to Step 3.

Step 2a: Claim (write marker + baseline)

Run:

bash ${CLAUDE_SKILL_DIR}/scripts/claim-session.sh --project-dir "$(pwd)"

Report the three file paths printed. These are the marker and baseline files — do not commit or delete them. They live inside .git/ and are not tracked.

Stop here.

Step 2b: Release (remove marker + baseline)

Run:

bash ${CLAUDE_SKILL_DIR}/scripts/release-session.sh --project-dir "$(pwd)"

No output is expected. Stop here.

Step 3: Detect coworkers

Look up the current session's baseline files (if --claim was run earlier this session). Then run detection:

bash ${CLAUDE_SKILL_DIR}/scripts/detect-coworkers.sh \
  --project-dir "$(pwd)" \
  --baseline-status .git/.claude-baseline-$$.status \
  --baseline-stash .git/.claude-baseline-$$.stash

If no --claim was run, omit the --baseline-* flags — drift detection will return unknown but marker and process signals still work.

Step 4: Interpret the verdict

Parse the VERDICT= line from the script's output:

Verdict	Meaning	Action
clear	No coworker detected	Proceed; still prefer explicit git add <paths> over git add -A
drift_detected	Files appeared since baseline but no other process/marker found	Inspect NEW_STATUS_LINES — may be coworker or may be a forgotten earlier edit. Ask the user before stashing.
coworker_detected	Another agent/process is active in this clone	Do not stash, restore, or reset. Report the MARKER_PID / PROC_PID entries. Recommend the user switch to a worktree.

Step 5: Report findings

Print a short summary:

1. Verdict
2. Count of markers + processes + drift entries
3. If non-clear, the specific PIDs or changed files
4. Recommended next action (worktree, ask user, proceed with explicit paths)

Post-actions

• On drift_detected or coworker_detected: do not run git stash, git reset --hard, git checkout -- ., or git clean in this session. Stage only explicit paths.
• Suggest the user run git worktree add ../$(basename $(git rev-parse --show-toplevel))-<task> for a clean isolated checkout.

Integration

Other git-plugin skills should invoke this via SlashCommand before destructive operations:

Before staging: Use SlashCommand to invoke `/git:coworker-check`.
If the verdict is not `clear`, stop and ask the user how to proceed.

Hook-based enforcement (blocking git stash / git reset --hard when a coworker is detected) belongs in hooks-plugin, not here.

Agentic Optimizations

Context	Command
Cheapest detection (no baseline)	bash scripts/detect-coworkers.sh --project-dir "$(pwd)"
Full detection with drift	Add --baseline-status + --baseline-stash from a --claim run
One-line verdict check	... | awk -F= '/^VERDICT=/ {print $2}'

Related Skills

• /git:maintain — invokes this before any stash/clean operation
• /git:commit — invokes this before staging when working in a shared checkout
• git-branch-pr-workflow — recommends worktrees as the structural fix