feat(source): add OpenClaw adapter

[ayagmar]

Objective

Add an openclaw source adapter for current transcript-style agent session files.

Source shape to support

• directory-backed JSONL transcripts under ~/.openclaw/agents/**/*.jsonl
• model/provider can change over the lifetime of a transcript
• only assistant messages with usage should emit events
• timestamps may need a file-level fallback

Implementation plan

1. Adapter file

   • add src/sources/openclaw/openclaw-source-adapter.ts
   • implement SourceAdapter with id = 'openclaw'

2. Discovery

   • follow the JSONL directory-backed pattern used by other adapters
   • discover transcript files deterministically
   • keep the first pass focused on the current transcript layout; avoid expanding scope into extra legacy index formats unless fixtures prove they are still required

3. Parsing

   • stream JSONL rows with readJsonlObjects()
   • track in-file state when model/provider change rows appear
   • emit events only for assistant rows that include usage
   • preserve explicit cost if the transcript exposes it
   • fall back to file mtime when message timestamps are missing
   • ignore user/system/non-usage rows without failing the whole file
   • use diagnostics for malformed or unusable rows when helpful

4. Wiring

   • register openclaw in src/sources/create-default-adapters.ts
   • keep it directory-backed via generic --source-dir openclaw=...
   • update supported-source count/order/help expectations

5. Tests and docs

   • add tests/sources/openclaw-source-adapter.test.ts
   • update shared registry/help tests and README.md

Code paths to touch

• src/sources/openclaw/openclaw-source-adapter.ts
• src/sources/create-default-adapters.ts
• src/utils/discover-jsonl-files.ts
• src/utils/read-jsonl-objects.ts
• src/sources/parsing-utils.ts
• src/domain/usage-event.ts
• tests/sources/openclaw-source-adapter.test.ts
• tests/sources/create-default-adapters.test.ts
• tests/cli/create-cli.test.ts
• README.md

Verification

• parser fixtures cover:
  • model/provider change rows updating parser state
  • assistant-only usage emission
  • explicit cost extraction
  • missing timestamp fallback to file mtime
  • irrelevant/non-usage rows ignored cleanly
• llm-usage daily --source openclaw --source-dir openclaw=<fixture-dir> works
• full validation passes:
  • pnpm run lint
  • pnpm run typecheck
  • pnpm run test
  • pnpm run format:check