drift

name	drift
description	Drift doc-to-code anchor conventions. Use when editing code that is bound by drift docs, updating docs, working with drift.lock, or when drift check reports stale anchors. Use when this capability is needed.
metadata	{"author":"fiberplane"}

Drift

drift binds markdown docs to code and lints for staleness.

Why this matters for agents

When you change code without updating the docs that describe it, those docs become stale. Stale docs get loaded as context in future sessions and produce wrong code based on wrong descriptions. This compounds — each session that trusts a stale doc makes things worse. drift makes the anchor explicit and enforceable so this feedback loop breaks.

Relink gate

drift link refuses to restamp a stale anchor without explicit review. When a target's signature has drifted, drift link prints the relevant doc section and, for symbol or markdown-heading anchors, current target context. In non-TTY runs it exits 1; in TTY runs it can prompt for confirmation.

This means you cannot blindly relink. You must review the doc prose and confirm it is still accurate. Use:

drift link docs/auth.md --doc-is-still-accurate

After you change code

Find which docs reference an exact target you touched:

drift refs src/auth/login.ts
drift refs src/auth/provider.ts#AuthConfig

Or check all docs at once:

drift check

If a doc is stale because of your change:

1. Run drift link <doc-path> — it will print review context, then refuse
2. Read the doc section and any printed target context to understand what's out of sync
3. Update the doc's prose to reflect what you changed
4. Run drift link <doc-path> --doc-is-still-accurate — succeeds now that you've reviewed
5. Verify: drift check

Do not skip this. Leaving a doc stale is worse than leaving it unwritten.

After you change a doc

Refresh all anchors in the doc to snapshot current state:

drift link docs/my-doc.md

This updates provenance on all existing bindings in drift.lock for that doc. Current drift link <doc-path> blanket mode does not discover or add inline @./ references from the doc body; add any new target explicitly with drift link <doc-path> <target>.

When you create new code

If the new code is covered by an existing doc, add an anchor:

drift link docs/auth.md src/auth/new-handler.ts

If the new code deserves its own doc, write one and link it:

drift link docs/new-feature.md src/feature/index.ts
drift link docs/new-feature.md src/feature/types.ts#Config

When you delete or rename code

If a bound file is deleted or renamed, drift check will report it as STALE with "file not found". Remove the stale anchor:

drift unlink docs/auth.md src/auth/old-handler.ts

If you renamed the file, unlink the old path and link the new one:

drift unlink docs/auth.md src/auth/old-name.ts
drift link docs/auth.md src/auth/new-name.ts

Update the doc prose to reflect the rename.

When you refactor

Refactors that move code between files or rename symbols can break multiple docs at once. Run drift check after refactoring to find all affected docs, then update each one.

When drift check fails in CI

Someone changed bound code without updating docs. Read the lint output to see which docs are stale and why, update the doc prose, then drift link to refresh provenance.

Anchor syntax

Bindings in drift.lock:

version = 1

[[bindings]]
doc = "docs/auth.md"
target = "src/auth/login.ts"
sig = "a1b2c3d4e5f6a7b8"

[[bindings]]
doc = "docs/auth.md"
target = "src/auth/provider.ts#AuthConfig"
sig = "c3d4e5f6a7b8a1b2"

[[bindings]]
doc = "docs/overview.md"
target = "docs/auth.md#authentication"
sig = "b3c4d5e6f7a8b9c0"

Anchors can target code files, code symbols (file#Symbol), or doc headings (doc.md#heading-slug). Heading fragments use GitHub-style slugs (lowercase, hyphens).

drift link writes bindings to drift.lock with content signatures (sig = "<hex>"). Content signatures are syntax-aware fingerprints for supported languages and raw-content fingerprints for unsupported whole-file anchors; unsupported symbol anchors cannot be fingerprinted. Staleness detection works without querying VCS history, so drift link works on uncommitted files — no need to commit first.

When relinking a stale anchor, drift link refuses and prints review context so you can inspect the change. Pass --doc-is-still-accurate to confirm the doc doesn't need updates.

drift lint also checks markdown links ([text](path.md)) in discovered markdown docs under the lockfile root for existence — broken links are reported as BROKEN without needing a lockfile entry.

Cross-repo docs (origin)

Docs installed from other repos (like this skill) carry origin on their bindings in drift.lock so drift check skips their anchors in consumer repos. If you're writing a doc that will be distributed to other repos, add origin to prevent false positives:

version = 1

[[bindings]]
doc = "docs/skill.md"
target = "src/main.ts"
origin = "github:your-org/your-repo"
sig = "a1b2c3d4e5f6a7b8"

Staleness

drift check reads bindings from drift.lock and exits 1 if any anchor is stale or markdown link is broken. Use drift check --changed <path> to scope checking to affected docs — useful in CI when you know which files changed. For supported languages (TypeScript-family files including TS/TSX/JS/JSX, Python, Rust, Go, Zig, Java), comparison is syntax-aware — formatting-only changes won’t trigger staleness. For changed anchors, stale reports include best-effort git context for the target file (author, commit, committer date, subject) so you can see what changed.

For --format json, the payload is schema_version: drift.check.v1 (see the repo’s docs/check-json-schema.md). There, blame.date is the committer date in ISO 8601 strict form, not author date — use it when you need a stable time ordering after rebases. The summary includes verification_state (none | partial | full) describing how many docs were actually checked versus skipped (e.g. origin mismatch).

Common reasons:

• changed after doc — file/symbol content differs from provenance snapshot
• file not found — bound file no longer exists
• file not readable — bound file exists but cannot be read
• symbol not found — bound symbol no longer exists in the file
• fingerprint unavailable — drift could not compute a target fingerprint
• baseline unavailable — the binding has no usable provenance
• origin mismatch — the binding belongs to another repo and is skipped
• link target not found — a markdown link points to a missing file

drift lint is an alias for drift check.

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Source: fiberplane/drift — distributed by TomeVault.