Project Spine Drift

Drift detection and resolution

Goal: determine whether the generated files still match the current inputs, and if not, help the user pick the right fix for each drift category.

Prerequisites

• .project-spine/export-manifest.json exists. If not, the project was never compiled — switch to project-spine-kickoff.
• CLI ≥ 0.8.1.

Step 1 — run the check

From the project root:

spine drift check

Exit codes:

• 0 — clean; nothing to do.
• 1 — drift detected; continue.
• 2 — can't check (missing manifest, unreadable inputs); investigate before proceeding.

The command prints a summary with three counters and writes drift-report.md + drift-report.json under .project-spine/.

Step 2 — interpret each drift category

Input drift

One or more of: brief.md, design-rules.md, tokens.json, repo profile, or the spine hash itself changed.

Fix: spine compile --brief ./brief.md --repo . (add the same --template, --design, or --tokens the project uses). This regenerates all exports from the new inputs.

The [input:tokens] drift kind fires specifically when the design tokens JSON file (DTCG or Tokens Studio) changed — typical when the design team re-exports from Figma.

Export hand-edits

A generated file (e.g. AGENTS.md) was edited manually after the last compile.

Two valid responses — ask the user which they want:

1. "Accept my edits as canonical" → the user wants the hand-edit to survive. They must edit the upstream input (brief.md, design-rules.md, or the workspace template) so a recompile reproduces the edit. Otherwise the next recompile reverts it.
2. "Discard my edits, regenerate" → run spine export --targets all to rewrite the exports from the stored spine.json.

The second option is only safe if the user confirms they don't need the hand-edited text. Never auto-discard.

Missing exports

A file listed in the manifest isn't on disk (deleted, moved, gitignored).

Fix: spine export --targets all to regenerate.

Step 3 — resolve and verify

After applying fixes, run spine drift check again. It should report clean.

CI usage (for automation conversations)

If the user is setting this up in CI:

# .github/workflows/spine-drift.yml
jobs:
  drift:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v6
      - uses: actions/setup-node@v6
        with: { node-version: 20 }
      - run: npm install -g project-spine
      - run: spine drift check --fail-on any

--fail-on levels: none, any, inputs (only fail on brief/design changes), exports (only hand-edits + missing files). Do not use --push; it is not routed in the public OSS CLI.

What to tell the user after resolving

If drift was caused by input changes, emphasise: "This is normal — you changed the brief or repo, so the generated files need to regenerate. The new spine.json hash is <hash>; keep that visible in commit messages."

If drift was caused by hand-edits, emphasise: "Hand-edits get overwritten on recompile. The fix is to edit the upstream brief.md / design-rules.md / template so the content regenerates naturally."

What NOT to do

• Do not manually edit spine.json to "fix" a hash mismatch. It's content-addressable — any edit desyncs everything.
• Do not suggest ignoring drift. The whole point is early detection.
• Do not recompile as a reflex. Run the drift check first and tell the user what it found before applying any changes.

Source: PetriLahdelma/project-spine — distributed by TomeVault.