# M3.5.5 — GET /skills and /skills/{name}: loadable skills catalog

| Field | Value |
|---|---|
| Phase | M3.5 — Distributed API Layer |
| Size | M — 1–3 days |
| Status | ✅ Done |
| Flags | — |
| Spec | inlined below |
| Blocks | M3.5.8 |
| Depends | M3.5.1, M4.1 (skill drafts exist locally) |

## Goal

Read-only endpoints for skill catalog. List all promoted skills (exclude `_drafts/`), fetch individual skill metadata and body. Skills are Obsidian notes; expose them over HTTP for agent discovery.

## Design

**List all loadable skills:**
```
GET /memory/skills?loadable=true
→ 200 {
  "skills": [
    {
      "name": "infra-root-causes",
      "description": "Identify root causes of infrastructure failures",
      "when_to_use": "When troubleshooting cluster or service outages",
      "argument_hint": "--project <name>",
      "promoted_at": "2026-08-20T10:30:00Z",
      "generated_from": null
    },
    ...
  ]
}
```

**Get one skill (metadata only):**
```
GET /memory/skills/infra-root-causes
→ 200 {
  "name": "infra-root-causes",
  "description": "...",
  "when_to_use": "...",
  "argument_hint": "...",
  "promoted_at": "2026-08-20T...",
  "generated_from": null
}
```

**Get skill with body (full content):**
```
GET /memory/skills/infra-root-causes?include_body=true
→ 200 {
  "name": "infra-root-causes",
  "description": "...",
  "body": "# Infra root causes\n\n..."
}
```

**Filters:**
- `loadable=true` (default): exclude `_drafts/`, return only promoted skills
- `loadable=false`: include everything (admin only — must have special apikey, documented in code)

## Technical

**Source:** Vault at `vault/skills/` contains skill markdown files. Each skill is a directory:
```
vault/skills/
  infra-root-causes/
    SKILL.md         <- frontmatter + body
```

**Frontmatter (YAML in SKILL.md):**
```yaml
---
name: infra-root-causes
description: Identify root causes of infrastructure failures
when_to_use: When troubleshooting cluster or service outages
argument_hint: --project <name>
generated_from: null | <L2 sha256>
---
```

**Drafts are in `vault/skills/_drafts/`:**
```
vault/skills/
  _drafts/
    new-skill/
      SKILL.md
```

Only load from `vault/skills/*/SKILL.md` (not `_drafts`), unless `loadable=false` is passed with an admin key.

## Steps

1. `GET /memory/skills` handler:
   - List `vault/skills/` directory (skip `_drafts/`)
   - For each `*/SKILL.md`, parse frontmatter
   - Extract: `name`, `description`, `when_to_use`, `argument_hint`, `promoted_at` (file mtime)
   - Parse `generated_from` field to show provenance
   - Return array

2. `GET /memory/skills/{name}` handler:
   - Load `vault/skills/{name}/SKILL.md`
   - Parse frontmatter and body
   - If `include_body=false` (default), return metadata only
   - If `include_body=true`, include markdown body

3. `loadable` query param (admin-only feature):
   - Default: exclude `_drafts/`
   - `loadable=false` with admin apikey: include `_drafts/` in listing
   - Non-admin key requesting `loadable=false` → 403 Forbidden

4. Error handling:
   - Skill not found → 404 with `{"error":"not_found","reason":"skill 'xyz' not promoted"}`
   - Malformed SKILL.md (frontmatter parse fails) → 500 with error (admin debug only)
   - Admin check: apikey must be in a whitelist (env var `MEM_ADMIN_APIKEYS` or config)

## Acceptance

- List endpoint returns all promoted skills
- Individual skill fetch works
- Drafts are excluded by default
- Admin with `loadable=false` sees drafts
- Skill body is optional (include_body param)
- Promoted_at field reflects file mtime

## Verify

**Harness:** Integration tests + filesystem fixtures.

**Setup:** Create test `vault/skills/` with:
- `vault/skills/test-skill-1/SKILL.md` (promoted)
- `vault/skills/test-skill-2/SKILL.md` (promoted)
- `vault/skills/_drafts/draft-skill/SKILL.md` (unpromoted)

**Integration test** — `tests/it_skills_endpoint.rs`:
1. `a1_list_skills_returns_promoted` — GET /skills returns array with test-skill-1 and test-skill-2.
2. `a2_drafts_excluded_by_default` — GET /skills does not include draft-skill.
3. `a3_drafts_included_with_admin_key` — GET /skills?loadable=false with admin apikey includes draft-skill.
4. `a4_non_admin_denied_drafts` — GET /skills?loadable=false with regular apikey returns 403.
5. `a5_get_single_skill_metadata` — GET /skills/test-skill-1 returns 200 with frontmatter fields.
6. `a6_include_body_true` — GET /skills/test-skill-1?include_body=true returns body field with markdown.
7. `a7_include_body_false` — GET /skills/test-skill-1?include_body=false (or omitted) does not include body field.
8. `a8_skill_not_found` — GET /skills/nonexistent returns 404.
9. `a9_promoted_at_is_file_mtime` — GET /skills/test-skill-1, assert promoted_at is a valid ISO timestamp close to SKILL.md's modification time.
10. `a10_generated_from_field` — SKILL.md with `generated_from: sha256xyz` is parsed and returned as-is.

**Command:** `cargo test -p mem-cli skills_endpoint`

**False pass:**
- Drafts never created in test fixtures. The default exclude-drafts logic is untestable without a draft.
- Admin key never tested. Non-admin path and admin path can be identical in code.
- Promoted_at never validated. Can return a fake date; file mtime is the only source.
- Frontmatter parsing doesn't validate required fields (name, description). A malformed SKILL.md is silently returned with null values.

## Traps

- Vault directory may not exist locally (only in deployed cluster). Start with a default empty list if vault/ is missing.
- YAML frontmatter parsing is fussy. A tab instead of spaces breaks YAML. Use a YAML parser (serde_yaml) and validate on load.
- File mtime precision: Unix mtime is seconds; SKILL.md edits may not increment it if done within the same second. Use actual write timestamp if available.
- Admin key stored in env var. If unset, default to deny (safer than default allow).

---

Background: [DESIGN.md § Skills — the procedural projection](../DESIGN.md#skills--the-procedural-projection)