* feat(agents): database-backed storage for custom agent definitions
Add an agent_storage.backend switch (default file, behaviour-unchanged) with a
db backend that stores each custom agent as a row in the shared SQL persistence
layer, so a multi-instance deployment sees the same agents on every node
(#4331, #4357). Introduces an AgentStore interface routing all read/write
surfaces, an agents table + migration 0006, startup validation, and a file->db
importer. Follows the thread_meta store / run_events backend-switch /
0003_scheduled_tasks migration patterns; no new dependency.
* fix(agents): make db storage path production-ready (review round 1)
Addresses review feedback on the db/sync agent-storage path:
- sql.py: mirror the async engine's per-connection SQLite PRAGMAs on the sync
engine (busy_timeout=30000, synchronous=NORMAL, foreign_keys=ON, WAL) so both
engines behave identically against the shared DB; guard the engine cache with
a lock (double-checked) so concurrent first-touch cannot build duplicate
engines or register the connect listener twice.
- routers/agents.py + routers/assistants_compat.py: offload the sync-store reads
that ran on the event loop (list/get/check, update's pre-read + legacy guard +
refresh, and assistants_compat's four list routes) via asyncio.to_thread — on
db+postgres each was a network round trip stalling the loop. Writes were
already offloaded.
- file.py: translate the create() mkdir(exist_ok=False) race FileExistsError
into AgentExistsError (router 409, matching SqlAgentStore's IntegrityError
path); correct the _write docstring — per-file atomic replace, two commits
sequential not transactional.
Tests: sync-engine PRAGMA + engine-cache reuse assertions; file create-race ->
AgentExistsError; strict Blockbuster anchor over the read endpoints so a
regression back onto the loop fails CI.
* fix(agents): address round-2 review on the db store path
- update_agent tool: align the docstring/inline comment with FileAgentStore._write.
Cross-field write atomicity is db-only; the file backend commits config then
soul via two sequential os.replace (a crash between them can leave a fresh
config.yaml beside a stale SOUL.md). The dropped partial-write *reporting* is
an intentional tradeoff — the stage-then-replace safety is preserved
(test_update_agent_soul_failure_does_not_replace_config still holds).
- SqlAgentStore.update(): true upsert. Catch IntegrityError on the
insert-on-missing branch, re-fetch and apply, so two concurrent first-time
writes (e.g. two setup_agent handshakes) converge instead of surfacing a raw
UNIQUE(user_id, name) violation as a 500. Symmetric with create().
- get_agent_store(): document the graph-subprocess config-resolution invariant
(the except->file fallback is a genuine no-config path, not a mask for a
misconfigured graph process) and pin it with two tests driving the real
get_app_config() file resolution: db resolves from an on-disk config.yaml,
file fallback when config is unresolvable.
* test(agents): cover SqlAgentStore.update() write-race upsert recovery
Mandatory-TDD test for the round-2 fix in 0680340a: two concurrent first-time
update()s where the loser's insert hits UNIQUE(user_id, name). Deterministically
forces the IntegrityError recovery path by making the first _row probe miss the
committed winner, and asserts last-writer-wins instead of a surfaced 500.
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