Part of #1132 (axis 2/7 of #1130). Registry: #782 — retry batch, DB-busy group. Follows up #1198 (Counter/base64 safe subset), which explicitly deferred all retry findings for per-case owner review.

What

Replaces the two genuine hand-rolled retry loops among the 14 detector findings with tenacity.AsyncRetrying (already a direct dependency; same style as error_recovery_service.py / production_limits_service.py). The other 12 findings are poll/pacing/work-distribution loops — adjudication table below, no code changes.

1. Database._with_busy_retry (src/database/facade.py)

SQLite-busy retry on the shared write path. Behaviour preserved exactly:

• fixed delay ladder from self._busy_retry_delays_sec via wait_chain(*(wait_fixed(d) ...)) — no jitter, no exponent;
• attempts = len(delays) + 1 via stop_after_attempt;
• non-busy OperationalError re-raised immediately (retry_if_exception(_is_retryable_busy_error));
• same per-retry and final warning logs; final failure raises DatabaseBusyError chained (from) to the last busy error.

2. TelegramCommandDispatcher._update_command_safely (src/services/telegram_command_dispatcher.py)

Unbounded exponential backoff on DatabaseBusyError. Behaviour preserved exactly:

• ladder INITIAL, 2×, 4×, … capped at MAX via wait_exponential(multiplier=INITIAL, max=MAX) — bit-identical float sequence (doubling is exact in binary);
• retry_busy=False → single attempt, busy swallowed with the same log line;
• non-busy exceptions swallowed with the same log line (status updates must never kill the run loop);
• sleep=asyncio.sleep keeps the existing test seam — suite patches of mod.asyncio.sleep still observe the retry sleeps;
• CancelledError still propagates (tenacity re-raises BaseExceptions, except Exception doesn't catch them) — test_run_loop_cancelled_reraises_when_update_busy stays green.

tenacity trap discovered (for the #782 registry)

AsyncRetrying awaits the result of fn(), so fn must be an async callable. _with_busy_retry receives a sync Callable returning a coroutine (lambda: begin_immediate(...)). Without the _wrap_async adapter the coroutine was never awaited → BEGIN IMMEDIATE never ran → transaction() hit cannot COMMIT - no transaction is active, leaking out as PytestUnraisableExceptionWarning (which is an error under the project's filterwarnings = ["error"], so it silently broke every DB write and red the whole suite). The adapter is one line (async def _runner(): return await action()); the dispatcher path is unaffected because its _update is already async def. Worth a line in #782 so future retry→tenacity conversions don't repeat it.

Retry/lifecycle check (#958 trap)

Both loops are local SQLite retries — no network, no billing. SQLITE_BUSY means the statement did not execute, so a retry cannot double-apply a write. tenacity adds no hidden extra retry layer here (no SDK involved); attempt counts and delay sequences are pinned by tests.

TDD / behavioural equivalence

7 characterisation tests were added first and verified green on the old implementation, then the swap landed with the tests untouched:

• test_database.py: exact sleep ladder on exhaustion; result returned after transient busy (slept exactly delays[0]); non-busy OperationalError raise-through with zero sleeps; DatabaseBusyError.__cause__ is the last busy error.
• test_telegram_command_dispatcher.py: exponential ladder doubles and caps (computed from module constants); retry_busy=False single-shot without sleep; generic error swallowed without retry.

Detector / baseline

• Findings for both converted functions are gone; --fail-on-new green.
• Baseline refreshed (13 → 12 entries): −2 fixed; pure path renames folded in (agent/manager.py → agent/backends/_stream.py, telegram/collector.py → telegram/collector_mixins/* — same findings, files moved by earlier refactors); +1 genuinely new finding recorded (web/scheduler/context.py:236, see table).

Adjudication of the remaining 12 findings (proposal — owner decides, #782)

Registry row (#782 journal):

Not merging — owner reviews (retry→library is in the dual-review category per the task brief).

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