Fosutilities API Catalog Update

FOSUtilities API Catalog — Update

This skill keeps .claude/skills/shared/api-catalog/ truthful and complete. The catalog is the discovery surface for every project that imports FOSUtilities (via the fosutilities-api-catalog skill); an entry that lies about the API is worse than a missing one, which is why the audit fails CI on stale entries but only warns on gaps.

Run this on macOS — that builds the full API surface. On Linux the Apple-only modules (FOSReporting) produce no symbol graph, and the audit skips the stale checks for those files, so a Linux run can pass while an Apple-only entry is stale. (This platform note lives here, in the maintainer skill — never in the catalog files themselves, which serve the customer audience only.)

Audit-driven workflow

1. Run the audit from the package root:

   swift scripts/api-catalog-audit.swift
   

   It builds the package (swift package dump-symbol-graph — may take a while), then reports three sections: Catalog gaps (warning), Stale entries (ERROR — exit code 1), and the DocC worklist (warning).

   Gotcha: the gaps section and the DocC-worklist section share the same Module: symbol [source file] line format. Any grep over the output must be scoped to one section, e.g.:

   swift scripts/api-catalog-audit.swift | awk '/== Catalog gaps/,/== Stale/'
   

   Note that piping through awk masks the audit's exit code — always check exit status on an unpiped run.

2. Fix stale entries FIRST — they fail CI. A stale entry means the API changed out from under the catalog: a symbol named in an entry's ### title no longer exists in that file's modules. Read the source to find what happened, then either update the entry's title symbols (rename), rewrite the entry (redesign), or remove it (deletion).

   Cross-module caveat: each catalog file's stale universe is only its own modules' symbol graphs (see moduleToCatalog in the audit script). A title symbol that actually lives in another file's module reports stale even though it exists. Remediation is moving the entry to the owning module's catalog file — or, rarely, the ignore list.

3. Write a curated entry for each gap, per the entry format rules below. Always read the actual source first — never write an entry from the symbol name alone. If the symbol is not customer-reachable (deprecated, compatibility shim, macro plumbing), add its base identifier to scripts/api-catalog-ignore.txt with a # comment stating the reason — never leave a silent gap. The comment goes on its own line above the identifier: the script only strips full-line comments, so an inline name # reason would fail to match the symbol.

4. Update the reach-for index when a new entry serves a reach that the discovery skill (.claude/skills/fosutilities-api-catalog/SKILL.md) doesn't index yet. Index lines are keyed by what the implementor is reaching for (Reaching for URLSession…), never by our library layout, and point to a real ## header: `FILE.md § Section`.

5. Report the DocC-worklist count. No DocC action happens in this workflow — the count is the measurable backlog for the separate DocC effort. Just surface it in your report so the trend is visible.

6. Re-run the audit and repeat until: 0 stale entries, 0 non-ignored gaps, exit code 0 (checked on an unpiped run — see step 1). Catalog-only edits don't invalidate the symbol graphs, so re-runs can skip the package rebuild by passing --symbolgraph-dir <dir> with the symbol-graph directory the first run produced (under .build/).

7. Bump the plugin version in .claude-plugin/plugin.json. Consumers only receive catalog and skill updates on a version bump — an unbumped update ships to no one. Catalog and skill content changes take a minor bump (consumers should receive them; this repo's practice is minor bumps for skill-doc updates); reserve patch bumps for typo-level fixes.

Non-audit path: index and structure maintenance

Some catalog work has no audit signal:

• Adding or adjusting reach-for index lines for already-catalogued capabilities (a reach was missing, or its wording didn't match how implementors think): edit the discovery skill's index directly, then do step 7 (version bump).
• Renaming a ## section or splitting a catalog file: sweep the reach-for indexes — the discovery skill and any CLAUDE.md index blocks — for dangling `FILE.md § Section` pointers and fix them. Pointers are not audited; a rename silently breaks them.

Entry format rules (binding)

These rules are the single source of truth for catalog entry format. They exist because the audit parses entries mechanically and because the catalog ships on a public plugin surface.

1. ## categories mirror the library's source folders (e.g. ## Coding for Sources/FOSFoundation/Coding/). Each category opens with 1–2 orientation sentences that cover everything in the section — including naming internal files as internal when relevant, so a reader doesn't go hunting for API that isn't public. Exception: multi-module catalog files (like FOSTesting.md, covering FOSTesting/FOSTestingUI/FOSTestingVapor) use one ## per module in library-hierarchy order, with categories nested beneath as needed — do not restructure them to per-folder ## headers, or the discovery skill's § pointers break.

2. ### titles are task-framed with the entry's own symbols in backticks in the title line. The title line is the audit's only freshness anchor — prose and example backticks are ignored by design.

   • Label-free symbol forms only: count(), never count(of:). The parser tokenizes on non-identifier characters and would flag of as a stale symbol.
   • Never backtick stdlib/Foundation/SwiftUI/Vapor types in titles — they aren't in our symbol graphs and would report stale. Mention them in prose or examples, which the audit ignores.
   • Only symbols owned by THIS file's modules go in titles (stale checks are scoped per file). A cross-module symbol goes in prose with a pointer to its own catalog file.
   • Apple-only symbols need the marker. A title whose symbols are SwiftUI/UIKit-gated (#if canImport(SwiftUI), #if os(iOS), …) inside a module that still builds on Linux must end with <!-- apple-only --> (invisible when rendered). Without it, Linux CI reports the symbols stale — they're absent from Linux symbol graphs. On macOS the marker is inert, so full stale enforcement still happens on every local/update-skill run. Verify the marker path with FOS_AUDIT_ASSUME_NON_APPLE=1 if needed.
   • Mixed title grammar is fine: imperative ("Compare versions — …") or noun-phrase ("Codable JSON round-trip — …").

3. Mandatory "Reach for this when:" line describing the reader's mid-task moment — the situation they're in, not a restatement of the API name. Optional "Don't:" line naming the concrete reinvention the entry replaces (Don't hand-roll JSONDecoder configuration…).

4. Examples are short and real. 2–4 lines for call-style APIs; up to ~8 lines for inherently structural declarations (type conformances, macro expansions). Never padded to look thorough. Every example must be verified against real source — an example calling a nonexistent API is the catalog's worst possible failure.

5. Contracts, never representations. The catalog is a public, plugin-shipped surface: no encoded shapes, token formats, byte layouts, or internal implementation details. State what the API guarantees, not how it does it.

6. One entry may cover a small family of symbols reached for as one capability (e.g. an encode/decode pair) — but every family symbol goes in the title backticks, or the audit reports the missing ones as gaps.

7. House style: honest limitation notes (say what an API does not do); cross-references between related entries; generator-skill pointers limited to one prose line; customer audience only — no maintainer or tooling commentary in catalog files (that belongs here).

Canonical example

From FOSFoundation.md § Coding — title symbols as freshness anchor, family in one entry, "Reach for" + "Don't" lines, minimal verified example:

### Codable JSON round-trip — `fromJSON()` / `toJSON()` / `toJSONData()`
Reach for this when: converting any Codable to/from JSON strings or Data.
Don't hand-roll `JSONDecoder` configuration — these apply the library's standard
coding strategy (dates, keys) consistently with the server.

```swift
let user: User = try jsonString.fromJSON()
let json = try user.toJSON()
let data = try user.toJSONData()
```

Why these rules protect the architecture

Entries state contracts, never representations — the catalog ships publicly with the plugin, and publishing an encoded shape or internal layout there would make it a de-facto schema consumers parse and depend on, freezing internals forever (see CLAUDE.md, "Encapsulation Is the Precondition SOLID Assumes"). Titles are the audit's freshness anchor precisely so the catalog cannot silently lie: any entry whose title symbols drift from the real API fails CI. Prose and example backticks are ignored by design — they may freely mention foreign types and context without polluting the freshness check.