fix(memory): team-scoped memories were never stored — null agent_id threw a swallowed TypeError

[escapeboy]

The bug

StoreMemoryAction::execute() advertises ?string $agentId, but storeChunk() and every write-gate helper below it declared a non-nullable string. Any team-scoped write throws:

StoreMemoryAction::storeChunk(): Argument #2 ($agentId) must be of type string,
null given, called in .../StoreMemoryAction.php on line 88

execute() wraps the chunk loop in try/catch and logs that at WARNING, so it never surfaced anywhere: the job reports success, the distillation watermark advances past the events, and nothing is stored. Silent, permanent data loss for every team-level memory.

DistillTeamEventsAction passes agentId: null explicitly, so the nightly digest has never worked.

Reproduced on production

memories total: 0            # zero rows, ever

A live distil run for a real team:

{"team_id":"019cb001…","events":61,"stored":0,"window_start":"2026-08-03T09:09:20+00:00"}
memories before=0  after=0

…while the model had produced a perfectly good 625-character digest, and the gateway, embeddings and config were all healthy. Calling StoreMemoryAction::execute(agentId: null) directly reproduced the exact TypeError above in the swallowed warning.

Fix

Widen $agentId to ?string through storeChunk, evaluateWriteGate, handleUpdate, handleAdd, mergeContent.

The where('agent_id', $agentId) lookups need no change — Laravel's where() maps a null value to whereNull.

How it was found

By validating the failed_jobs backlog rather than accepting that the recent silence meant the failures were fixed. The nightly DistillTeamEventsJob failures stopped on 2026-07-29 — two days before the fix that supposedly addressed them (#131, 2026-08-01), so that fix could not be the reason. Chasing the real reason led here.

Worth noting: #131 made the symptom quiet by catching AiAccessUnavailableException and advancing the watermark. This PR fixes the case where there is no exception to catch at all.

Verification

• 196 tests pass across Unit/Domain/Memory + Feature/Domain/Memory
• Regression test asserts all five signatures accept a null $agentId
• pint clean; phpstan reports zero errors in the touched files (the 73 in that path are pre-existing — identical count with the change stashed)