Skill Provenance

The Problem This Solves

Skill projects move between sessions, surfaces (Chat, IDE, CLI, Cowork), platforms (Claude, Gemini CLI, Codex, Copilot), and local storage (Obsidian, working directories, git repos). Version identity gets lost when it lives only in filenames. A file renamed from SKILL_v4.md to SKILL_v5.md with no internal record of what changed creates ambiguity.

This skill establishes three conventions that prevent that:

1. Version identity lives inside files when their format allows it, and always in the manifest.
2. A recent changelog travels with the skill bundle, while longer history can live in the source repo.
3. A manifest lists all files in the bundle so any session can verify completeness.

What Gets Versioned

A skill bundle is a SKILL.md plus all associated files. Typical contents:

• SKILL.md (the skill definition)
• evals.json (evaluation suite)
• Generation scripts (e.g., generate.js, generate.py)
• Output artifacts (.docx, .pdf) produced by evals or real use
• Handoff notes
• Source material provided by the user (tracked but not versioned)

The skill itself (SKILL.md) and evals are the primary versioned artifacts. Scripts and outputs are tracked by the manifest but version with the bundle rather than independently. Handoff notes are optional convenience artifacts.

Internal Version Header

Files that can safely carry YAML frontmatter begin with a YAML frontmatter block (or extend an existing one) containing these fields:

---
skill_bundle: my-skill            # bundle name, stable across versions
file_role: skill                  # skill | evals | script | output | handoff
version: 5                        # integer, monotonically increasing
version_date: 2026-02-10          # date of this version
previous_version: 4               # null for v1
change_summary: >
  Rewrote Phase 5 layout rules. Removed per-section page breaks.
  Added content flow check. Added validation checklist as standalone final page.
---

Rules

version is an integer for per-file tracking. It counts revisions to that specific file within the bundle. The bundle-level version (bundle_version in MANIFEST.yaml) uses semver.

change_summary is required for every version after v1. One to three sentences. It must describe what changed, not just that something changed.

previous_version creates a chain. Any session can trace the lineage.

file_role values:

• skill — the SKILL.md itself
• evals — the evals.json file
• script — generation scripts, utility scripts
• output — rendered artifacts (.docx, .pdf)
• handoff — session handoff notes
• source — user-provided source material (tracked, not versioned)
• reference — documentation in references/ loaded on demand
• asset — templates, images, fonts in assets/ used in output
• agents — platform UI metadata (e.g., Codex's agents/openai.yaml)

For files that cannot safely carry YAML frontmatter (binary files and strict-format files such as .json or executable .sh), the manifest tracks their version and its version field is authoritative.

SKILL.md frontmatter constraint: The Agent Skills open standard (agentskills.io) requires name and description. Different platforms enforce different rules about additional fields:

For maximum portability, keep SKILL.md frontmatter to name and description only. If the canonical bundle needs attribution or visible SKILL.md metadata, use the spec's metadata field there and generate a derived minimal copy for strict platforms:

---
name: my-skill
description: What the skill does.
metadata:
  skill_bundle: my-skill
  file_role: skill
  version: 3
  version_date: 2026-02-10
  previous_version: 2
  change_summary: >
    Added Phase 6 validation step.
---

If targeting Codex or other strict platforms directly, omit metadata from SKILL.md entirely. The manifest tracks SKILL.md's version either way, so no version information is lost.

Note on spec support: The agentskills.io spec formally supports metadata as an arbitrary key-value map, with version shown as an example use. This means the metadata.version approach is now spec-blessed, not a Claude-only extension. However, the spec's version is a static label — it does not address staleness tracking, changelogs, or bundle integrity. Prefer manifest-based tracking as the default and use metadata only when you need version info visible in the file itself.

Manifest

The manifest is a YAML file named MANIFEST.yaml at the root of the skill bundle directory — the same level as SKILL.md. When the bundle is packaged as a .skill ZIP, the manifest lives inside the ZIP. It is the single source of truth for what the bundle contains.

bundle: my-skill
bundle_version: 5.1.0
bundle_date: 2026-02-10
description: >
  Skill for generating professional documents from source material
  and user briefs. Handles research, structuring, and formatting.

compatibility:
  designed_for:
    surfaces:
      - chat
      - cli
      - ide
    capabilities:
      - minimal SKILL.md frontmatter
      - local filesystem access
      - optional git workflow
  tested_on:
    - platform: Anthropic Claude
      model: Claude Opus 4.6
      surface: Chat
      status: pass
      date: 2026-02-10
    - platform: Anthropic Claude
      model: Claude Sonnet 4.5
      surface: Chat
      status: partial
      date: 2026-02-09
      notes: Misses staleness detection on complex bundles
  spec_version: agentskills.io/1.0
  frontmatter_mode: minimal
    # minimal = name + description only (Codex, Gemini CLI, max portability)
    # metadata = includes metadata block (any platform supporting the spec's metadata field)

dependencies: []
  # List skill names this bundle depends on. Omit or leave empty if none.

deployments:
  api:
    version: 1759178010641129
    workspace: docs-prod
  claude:
    scope: user
  perplexity:
    package_format: zip

files:
  - path: SKILL.md
    role: skill
    version: 5
    hash: sha256:abc123...
    note: Canonical skill definition

  - path: evals.json
    role: evals
    version: 3
    hash: sha256:def456...
    note: 7 evals including real-content synthesis

  - path: scripts/generate.js
    role: script
    version: 4
    hash: sha256:ghi789...
    note: Generation script for eval 3

  - path: outputs/eval3-output.pdf
    role: output
    version: 4
    hash: sha256:jkl012...
    note: Rendered eval 3 output, 10 pages, validated

  - path: sources/article-1.md
    role: source
    version: null
    hash: sha256:pqr678...
    note: Source article 1 (published)

Rules

bundle_version uses semver (MAJOR.MINOR.PATCH). Bump MAJOR for breaking changes to the skill's model or interface, MINOR for new features or capabilities, PATCH for fixes and documentation updates. Per-file version fields remain integers — they are revision counters, not release identifiers.

hash is sha256 of the file contents. This is how a new session verifies that the file it received matches what the manifest claims. Compute on save, verify on load.

deployments is optional. Use it to record deployed or installed copies of the same bundle when you want traceability across surfaces. Keep bundle_version as the author-side semver source of truth. Platform-native versions (for example API timestamps) stay in deployments, not in bundle_version.

version: null for source files. They are tracked for completeness but not versioned by this system.

Paths are relative to the bundle root. No absolute paths.

MANIFEST.yaml is not listed in files. Self-hashing is recursive. Treat the manifest as the bundle's control file and verify it via git, transport checksums, or the surrounding package when needed.

The .skill Package Format

Claude's settings UI exports and imports skills as .skill files. These are standard ZIP archives containing a directory named after the skill. The versioning artifacts (MANIFEST.yaml, CHANGELOG.md, README.md) live inside this directory at the same level as SKILL.md:

skill-name.skill (ZIP)
└── skill-name/
    ├── SKILL.md
    ├── MANIFEST.yaml
    ├── CHANGELOG.md
    ├── README.md
    ├── assets/
    └── references/

Claude's settings importer only looks for SKILL.md and the directory structure it expects (references, assets). It ignores files it doesn't recognize. This means the versioning artifacts travel safely inside the .skill ZIP without affecting import/export behavior.

When bootstrapping or updating a bundle, always include the versioning artifacts in the .skill ZIP so they survive round-trips through Claude's settings UI.

Some uploaders only accept .zip or .md. In those cases, rename the archive from .skill to .zip without changing its contents.

The spec recommends keeping SKILL.md under 500 lines and moving detailed reference material to separate files. Provenance artifacts fit naturally into that model: MANIFEST.yaml and CHANGELOG.md are load-on-demand resources, not always-loaded instructions.

Claude Code provides a ${CLAUDE_SKILL_DIR} variable for bundle-relative paths. Other platforms may not. Direct relative paths like ./validate.sh work when the working directory is the bundle root.

The .skill ZIP only carries the skill definition and its references. Bundles can still track evals, scripts, rendered outputs, and handoff notes outside the archive. The manifest remains the complete inventory, not just the package inventory.

Changelog

The changelog is a file named CHANGELOG.md at the root of the skill bundle directory, alongside SKILL.md and MANIFEST.yaml. In the bundle, it carries recent history with newest entries at the top. If the canonical source lives in git, older entries can be archived in a repo-level changelog outside the bundle.

# Changelog

## 5.1.0 — 2026-02-10
- SKILL.md: Rewrote Phase 5 layout rules. Removed per-section page breaks.
  Added content flow check and a standalone validation checklist.
- evals.json: Not yet updated (stale, needs alignment).

## 5.0.0 — 2026-02-09
- SKILL.md: Reworked body flow rules and added an optional appendix.
- evals.json: Eval 3 expectations updated for content flow.

Rules

Each entry names every file that changed and what changed in it.

Files that are stale get called out. If SKILL.md changes but evals.json was not updated to match, the changelog says so. This prevents the silent drift that caused the v4/v5 confusion.

Entries are human-written prose, not auto-generated diffs. The point is to communicate intent, not enumerate line changes. Git diffs are available when the bundle is in git.

Bundle changelogs can be trimmed. Keeping the last 5-15 entries in the bundle is reasonable if the source repository maintains a full append-only changelog elsewhere.

Session Protocol

Opening a session

When a skill bundle is loaded into a new session:

1. Read MANIFEST.yaml first.
2. Verify all listed files are present. Report any missing files.
3. For files with hashes, verify hashes match. Flag mismatches. In local environments, users can run validate.sh before uploading for reliable hash verification without LLM computation.
4. Read CHANGELOG.md to understand recent changes.
5. Check for staleness: if any file's version is lower than the bundle version, or if deployments clearly show a deployed copy behind the local bundle, flag it and ask the user whether it needs updating.
6. If MANIFEST.yaml is missing, treat the bundle as unversioned. Offer to create one by inventorying the files and asking the user for version context.

Saving / closing a session

When work is complete and files are being delivered:

1. Update internal version headers for changed files that use them.

2. Update MANIFEST.yaml with new versions and hashes for every changed versioned file, including manifest-only files. If the user deployed or reinstalled the skill this session, update any relevant deployments metadata too.

3. Add a new top entry to CHANGELOG.md.

4. If any versioned file was changed but another dependent file was not updated (e.g., SKILL.md changed but evals.json was not updated), note the staleness explicitly in the changelog entry.

5. Deliver the full bundle to the user, or at minimum the changed files plus the updated MANIFEST.yaml and CHANGELOG.md.

6. If the user indicates the bundle is destined for a git repo, provide a ready-to-use commit message derived from the changelog entry. Format:

   skill-name MAJOR.MINOR.PATCH: one-line summary
   
   - file1.md: what changed
   - file2.json: what changed
   - Stale: file3.js (not updated this session)
   

   Return the message inline by default. Only write a transient git_commit.txt file if the user explicitly asks for a file or if the environment makes file output materially more convenient.

Handoff between sessions

A handoff note is a snapshot of project state for the next session. It should include:

• Current bundle version
• What was accomplished this session
• What is stale and needs attention
• What the next session should do first
• Any decisions made that are not yet reflected in the files
• Per-file change summaries: for each file modified this session, a brief description of what changed (section added, field removed, logic rewritten, etc.). This is more granular than the changelog entry and helps the next session verify the work without re-reading every file.

Create a handoff note only when crossing a non-persistent boundary or when the user explicitly asks for one. In filesystem-native environments with a current manifest, changelog, and git history, it is usually unnecessary. When created, it replaces the previous handoff note; previous handoffs live in changelog history.

Conflict resolution

When a session finds version conflicts (e.g., a file claims v5 but the manifest says v4, or two files claim different bundle versions):

1. Present the conflict to the user with the specific discrepancy.
2. Show what each version claims via its change_summary.
3. Default recommendation: trust the most recent version_date.
4. Always ask the user for explicit confirmation before proceeding.

Never silently resolve a version conflict. The whole point of this system is to make conflicts visible.

Cross-Surface and Cross-Platform Considerations

Treat one skill as moving through three states:

• Canonical source bundle: The working copy in git or local storage. Keep MANIFEST.yaml and the active CHANGELOG.md here. This is the author-side source of truth. If you maintain a full archive in git, keep it at repo root or another repo-level path outside the bundle.
• Strict-platform install copy: A derived copy for Codex, Gemini CLI, Perplexity, or other loaders that only accept name and description. Strip the metadata block from SKILL.md, set frontmatter_mode: minimal, recompute hashes in that copy, and leave the canonical bundle unchanged unless you intentionally promote the derived copy.
• Registry or settings package: A consumer package such as a .skill ZIP or ClawHub upload. It may omit development-only files, but its MANIFEST.yaml must describe exactly what the package contains. Update deployments only after a real publish, reinstall, or redeploy.

Surface notes:

• Claude Chat: Stateless upload/download boundary. Verify on open and consider a handoff note.
• Claude Cowork / Claude Code / Claude Agent SDK: Persistent filesystem. The manifest and changelog live with the bundle.
• Claude API: Deployment versions live in deployments, not in bundle_version.
• Other agentskills clients: Unknown files are ignored safely. .agents/skills/ can act as a neutral install path.

General principle: the manifest and changelog stay authoritative, and transformed install or publish copies are derived artifacts, not silent edits to the canonical bundle.

Trust and Audit

Use the manifest, changelog, hashes, and optional deployment metadata to verify what belongs in the bundle, whether files still match their recorded state, what changed, and which installed or deployed copies may now be stale. If a bundle comes from an untrusted source, verify it first.

File Naming

Versioned files use stable names without version numbers:

• SKILL.md (not SKILL_v5.md)
• evals.json (not evals_v3.json)
• generate.js (not generate-v4.js)

The version lives inside the file (via the header) and in the manifest, not in the filename. Version-numbered filenames are how we got into trouble in the first place.

Exception: if a user's local storage requires version-in-filename for their workflow, the manifest is the tiebreaker for which version is canonical. Internal version identity must still match.

Bootstrap

To version an existing unversioned skill bundle:

1. Inventory all files present — read the directory structure or uploaded file list. Do not ask the user to list files; determine this yourself.
2. Ask the user what version number to assign. If there's a handoff note or other context, propose a number based on the history.
3. Add internal version headers to files that can safely carry them and record manifest-only versions for strict-format files.
4. Generate MANIFEST.yaml with hashes.
5. Create CHANGELOG.md with a single entry summarizing known history.
6. Deliver the versioned bundle.

This is a one-time operation per skill bundle.

Origin

Developed by Snap Synapse. Canonical source: https://github.com/snapsynapse/skill-provenance