fixtures: golden data dir — real records, production read paths

Owner-manufactured teach master (chat_mv27rrra: compaction, subagent-abort,
every teach tool) + practice lifecycle (chat_mv293wv5: the full marker cycle
including the first-ever problem-dismissed), the real graph ledgers, five
jobs across the kind x status matrix, and settings. tests/golden-fixtures
reads all of it through the stores via the LH_DATA_DIR seam and pins the
fixture law: real data parses, flattens to a legal LLM wire, derives the
graph, covers every custom-marker kind, and reads never write.

Fixture law: an intentional format change updates these files in the same
commit; an unintentional one fails the suite.

docs/development.md

@@ -170,6 +170,7 @@ All deterministic, no LLM, no network (engines are injected — pi-ai's faux pro
 2. **Server flows** — `handleChatRequest` driven end-to-end with scripted engines: persistence, liveness, steer claiming, the wake pipeline (409 retry, quiz deferral, idempotency), crash recovery, the data-dir seam (including a fresh child process).
 3. **Sub-agent loops** — researcher/demo-builder/visual-maker with fake headless APIs; the extraction pipeline end-to-end (audit drops, failure-checkpoints-nothing, single-flight, abort).
 4. **Render tests** — transcript, cards, docks, composer, sidebar, coverage via React server-side rendering.
+5. **Golden fixtures** (`tests/fixtures/golden-data/`) — a REAL data dir (real records produced by the app, never hand-edited), copied to a temp dir and read through the production paths via the `LH_DATA_DIR` seam. Pins that real data parses, flattens to a legal LLM wire, derives the graph end-to-end, covers every custom-marker kind, and that reads never write. **The fixture law:** an intentional on-disk format change updates the fixtures in the same commit — see the fixture README.
 
 ## Lineage