ad-handoff

<background_information> Process scaffold for compacting a long or near-exhausted session into a handoff document. Output is a single markdown file in the OS temp directory; the next session reads it and continues. Helper, not blocker — the senior engineer keeps decision authority over what survives the compaction.

The skill exists because long sessions accumulate inherited bias (WORKFLOW §12 — "almost right" failures compound) and because session-window pressure forces ad-hoc summarisation that loses the parts the next agent actually needs. Handoffs replace ad-hoc summarisation with a structured artifact.

Codex subagents and sessions do not share the parent conversation history by magic, and /clear discards local context. Handoff via the OS temp dir is the durable bridge between Codex sessions or explicit subagent work — treat it as load-bearing, not optional. Codex auto-trigger on description keywords is less mature than Claude Code's; if auto-invocation does not fire when the user mentions handing off, compacting, or /clear, invoke this skill manually. </background_information>

Route elsewhere when:

• The work is finishable in the current turn → finish it; do not pre-emptively hand off.
• The handoff target is a specific artifact (PRD / spec / task / ADR) → write that artifact via the matching ad-* skill instead. Handoffs do not replace persistent decision records.
• The user wants to commit work-in-progress → ad-commit or finish the change first.

Step 1 — collect live state. Do not duplicate content that already lives in repo artifacts; reference those by path.

Capture:

• Working tree — git status --short, current branch (git branch --show-current), divergence (git log --oneline @{upstream}..HEAD if a remote is set).
• In-progress diff — git diff + git diff --staged. If the combined diff is >300 lines, summarise per-file and tell the next agent to re-read it with git diff.
• Open artifacts — files touched but uncommitted; task file under doc/tasks/ driving the work (if any); spec under doc/specs/ it implements (if any); ADR being drafted under doc/adr/ (if any).
• Unresolved decisions — questions the user posed that you have not answered; questions you posed that the user has not answered. One bullet per open question, with a recommended-answer line where you have one.
• Recent errors / hook failures — verbatim, last error message + which command produced it.
• Repo hygiene — git worktree list, git branch --merged <default>, git branch --no-merged <default>, stray untracked files at the repo root. Delete the merged branches: git branch -d <name> refuses anything not fully merged, so git itself is the guard, and a merged branch's commits survive on the default branch and in the reflog — the blast radius WORKFLOW §7 asks you to match is near zero. Run it and report what was deleted. Everything else is reported with its command and never run: unmerged branches (including squash-merged ones, which git cannot distinguish from genuinely unmerged), worktrees, and stray files get git branch -D <name> / git worktree remove <path> written next to them. Those are the destructive cases — -D discards commits. Known limit, tested rather than assumed: squash-merged branches cannot be detected — git branch --merged, git cherry and a three-dot diff all miss them, because squashing rewrites the patch-id. Report as ambiguous; a heuristic that guesses here would authorise deleting real work.
• What the next agent should do first — one sentence, imperative.

References, not copies. Spec: doc/specs/0007-foo.md beats pasting the spec. The next agent will read those files fresh.