# Claude Code — Dev Guide for singularity-forge

See [AGENTS.md](AGENTS.md) for SF planning conventions and the promote-only state rule.
The foundational product contract is [ADR-0000: SF Is a Purpose-to-Software Compiler](docs/adr/0000-purpose-to-software-compiler.md).

## Build pipeline (MUST READ before editing extension source)

Source TypeScript files under `src/resources/extensions/sf/` are **not loaded
directly at runtime**. The loader (`src/loader.ts`) resolves extension entry
points from `dist/resources/extensions/sf/` (compiled `.js`) and copies them
to `~/.sf/agent/extensions/sf/` via `initResources`. Editing a `.ts` source
file has **no effect** until you recompile:

```bash
npm run copy-resources   # tsc --project tsconfig.resources.json + file copy
```

This clears and rebuilds `dist/resources/` in one shot. Expect ~60–90 s on
first run; subsequent runs reuse tsc's incremental cache if you keep one.

The `dist-redirect.mjs` resolver (used by tests and `dev-cli.js`) only
redirects `.js → .ts` for imports whose `parentURL` is inside `/src/`. Files
loaded from `~/.sf/agent/extensions/sf/` (compiled JS) are **not** redirected.

## Running tests

**Use vitest — no pre-compilation step needed.**

```bash
# Run a specific test file (fast, no coverage overhead):
npx vitest run src/resources/extensions/sf/tests/<name>.test.ts --config vitest.config.ts

# Run the full SF extension test suite:
npm run test:unit

# Run only tests affected by recent changes (fast feedback loop):
npx vitest run --changed --config vitest.config.ts

# Watch mode for active development:
npx vitest --config vitest.config.ts
```

**Do not use Python for one-off JSON/hash work.** The resource fingerprint in
`~/.sf/agent/managed-resources.json` is computed by Node's SHA-256 — Python's
`hashlib` produces a different result for the same files, which breaks the
fast-path check in `initResources` and causes a 30-60 s full resync on every
launch. Use `node -e` (or `jq`) for any shell-level JSON/hash operations in
this repo.

## Lint: test-import-drift guard

**Problem:** Test files with itemized `import { foo } from "module"` and many
named imports (≥6) carry a maintenance trap — adding a new `describe(...)`
block that uses a module function without updating the import list causes
`ReferenceError` at vitest run-time, not at lint time. Biome's ESM lint does
not catch `used identifier not declared`.

**Guard:** `npm run check:test-imports` runs `scripts/check-test-imports.mjs`
which statically scans all `*.test.{js,mjs,ts}` files for this anti-pattern.
It flags files that have ≥6 itemized imports AND reference a camelCase identifier
not in the import list. False positives for test locals, vitest globals, Node
builtins, and keyword-like words are filtered.

The check is NOT integrated into `npm run lint` by default (too broad for the
current threshold) but runs as `npm run check:test-imports`. Add it to the
`lint` script if the threshold is later lowered.

**Convention:** Test files whose subject is the public surface of a SF module
(migration tests, integration tests over a module's full API) should use
`import * as <Namespace> from "<module>"` instead of itemized imports when
≥6 named members are needed. This avoids the maintenance trap entirely.
The check script targets files with ≥6 itemized imports + an undeclared camelCase
identifier. Known false-positive categories are filtered (test locals, vitest globals,
Node builtins, keyword-like words, boolean flags), but some legitimate cases
may still appear in complex test files — use judgement when triaging output.

## Key directories

| Path | Purpose |
|------|---------|
| `src/resources/extensions/sf/` | Extension TypeScript source (edit here) |
| `dist/resources/extensions/sf/` | Compiled output (rebuilt by `copy-resources`) |
| `~/.sf/agent/extensions/sf/` | Installed copy (synced from dist on startup) |
| `src/resources/extensions/sf/prompts/` | Prompt templates (`.md`) |
| `src/resources/extensions/sf/tests/dist-redirect.mjs` | Module resolver hook for tests |

## Template variables

When adding a new `{{variable}}` to a prompt template in `prompts/`, you must:

1. Pass it in every `loadPrompt("template-name", { ..., newVar })` call site
   (`auto-prompts.ts` is the main one for execute-task).
2. Add it (with a sensible placeholder value) to any test that calls
   `loadPrompt("template-name", {...})` — see
   `src/resources/extensions/sf/tests/plan-slice-prompt.test.ts`.
3. Run `npm run copy-resources` to land the change in dist.

`loadPrompt` throws at runtime if any `{{var}}` in the template has no
corresponding key in the vars object — this is intentional to catch
template/code drift early.