sync

name	sync
description	Detect Spec to Code drift. Scan REQ/DESIGN/TASK specs for references to code that no longer exists, then report drift for review. Run after a hand-edit that moved or deleted code.
argument-hint	spec-tier-or-empty
allowed-tools	Task, Skill, Read, Glob, Grep, Bash(python3 scripts/sync/detect_spec_drift.py*)
user-invocable	true

Sync Command

Sync: $ARGUMENTS

The forward path (/spec -> /plan -> /build) turns intent into code. There is no clean reverse path. When you hand-edit code (refactor, hotfix, taste change), the spec drifts silently and the staleness surfaces only at /review time, late and often misattributed as "the spec was wrong" instead of "the spec needs updating". /sync closes that loop: it finds the drift while you still remember why you made the change.

What this slice does

This command detects Spec->Code drift and reports it. It does NOT auto-rewrite specs. Detection runs; patch proposal is a follow-up (see Step 3).

Triggers

Phrase	Action
/sync	Scan all spec tiers for stale code references
/sync .agents/specs/design	Scan one spec tier
detect spec drift	Run the detector and report drift

Process

Step 1: Detect drift

Run the drift detector against the specification tier:

python3 scripts/sync/detect_spec_drift.py --output-format human

The detector scans .agents/specs/requirements, .agents/specs/design, and .agents/specs/tasks for backticked references to code and artifact paths (scripts/..., build/scripts/..., .claude/skills/..., .claude/commands/..., templates/..., tests/..., src/...). Each reference is resolved against the working tree. A reference to a path absent on disk is drift: the spec points at code that moved or was deleted.

To scan one tier only, pass --target:

python3 scripts/sync/detect_spec_drift.py --target .agents/specs/design --output-format human

Exit codes (per ADR-035): 0 no drift, 1 drift found, 2 configuration error. Unsafe --target values (absolute paths, .., or symlink escapes) return exit 2. Unsafe spec references are reported as drift instead of probing outside the repo.

Step 2: Triage the findings

For each DRIFT line the detector reports (spec_file:line -> path absent on disk), decide which case applies:

• Code moved: the path was renamed. Update the spec reference to the current path.
• Code deleted: the capability was removed. Update the spec to reflect the removal, or restore the code if the removal was unintended.
• Intentional forward reference: the spec names a planned path that does not exist yet. Mark the line with a trailing <!-- sync-drift-ignore --> so the detector skips it.
• Unsafe reference: the spec uses .., an absolute path, or a symlink escape. Treat it as drift and update the spec to a repo-contained path.

Do not auto-apply edits. Confirm each case with the author of the change before touching the spec.

Step 3: Propose spec patches (follow-up, not in this slice)

Patch proposal via the spec-generator agent is tracked as a follow-up. When wired, /sync will hand the drift findings to Task(subagent_type="spec-generator") to draft REQ/DESIGN/TASK edits and write a record under .agents/specs/sync-log/ with the commit range it covered. Until then, apply the triage from Step 2 by hand and record the rationale in the PR description.

Principles

• Propose, do not auto-apply. A human approves every spec edit. The detector flags; it never rewrites.
• Detection is deliberate, not real-time. Run /sync after a hand-edit. Real-time drift detection during /build is a PostToolUse hook concern, out of scope here.
• The spec is a source of truth. Drift erodes that. Catching it early keeps the spec defensible for "what does this code actually do" questions.

Output

• The detector's VERDICT line (PASS or DRIFT) and per-finding spec_file:line -> path list.
• A triage decision per finding (moved / deleted / intentional).
• The spec edits applied or proposed, with rationale recorded in the PR description.

Verification

• Detector exits 0 only when no drift exists.
• Detector exits 1 when stale references exist.
• Detector exits 2 for unsafe targets, unreadable specs, or missing custom targets.
• Copilot CLI-generated skill matches this command source.

Anti-Patterns

Avoid	Why	Instead
Treating unreadable specs as clean	Hides drift behind an I/O failure	Fail closed with exit 2
Scanning absolute or parent targets	Walks outside the repository	Reject unsafe targets
Auto-rewriting specs	Changes source of truth without review	Report drift and require author triage

Extension Points

• Patch proposal via spec-generator.
• Additional reference roots in scripts/sync/detect_spec_drift.py.
• Sync log artifacts under .agents/specs/sync-log/.