## What happened
FN-8004's implementation work finished and passed review. The auto-merge
then failed with `Grok ACP turn failed: Internal error` — a ~20 second
provider blip — and the task was parked `status: "failed"` with 8 files
of complete, reviewed work stranded on its branch.
The park is the interesting part: `status: "failed"` is precisely what
tells recovery to stop. So a misclassification here isn't a missed
retry, it's **terminal**. Both recovery paths were disabled by the same
wrong verdict:
- `maybeRetryTransientMerge` (inline, 3 retries w/ backoff) — never
fired once (`mergeTransientRetryCount: 0`).
- `recoverTransientMergeFailures` (self-healing sweep, exists exactly to
rescue parked in-review tasks) — skipped it, gated on the same
classifier.
## Three defects fixed
**1. No AI-provider failure class existed.** The AI merge drives a real
LLM turn, but `classifyTransientMergeError` only modeled git/lease/spawn
faults. Adds `ai-provider-turn-failure`.
**2. ACP dropped the error detail.** `promptAcpSession` rethrew the SDK
error unchanged, discarding the JSON-RPC `code`/`data` — the only
evidence the fault was provider-side. ("Internal error" is just the
standard text for `-32603`.) It now preserves them, keeping the original
as `cause`:
```
Internal error (acp rpc code -32603, retryable)
```
Classification anchors on that envelope, **not** on the bare `"Internal
error"` — matching that unanchored would disguise genuine application
defects as retryable blips. Only provider-fault codes (`-32603`,
`-32000`..`-32003`) are retryable; caller-fault codes
(`-32600`..`-32602`) stay permanent, since retrying just repeats the
failing call.
**3. Sweep/inline asymmetry** (found while tracing; latent and
unreported). The inline gate accepted `isTransientError(msg) ||
classify(msg)`, but the sweep consulted **only** the classifier. So
`ECONNRESET` / `socket hang up` during a merge earned inline retries and
then went **invisible to the sweep** once parked — stranded forever. The
classifier now delegates to `isTransientError`, so both gates agree by
construction.
To keep that delegation from importing the detector's
`usage-limit-detector → logger` chain (the chain FN-5627 split the
classifier out to avoid, which would break
`notification-service.test.ts`'s partial `vi.mock`), the pure predicates
moved to the import-free leaf `transient-error-patterns.ts`, re-exported
from `transient-error-detector.ts`. All 13 exports preserved, verified
programmatically.
## Loosened budgets
Per request, so more self-heals. Both apply **only** to errors already
proven transient; the ceiling and
`merger:transient-failure-budget-exhausted` audit path remain.
| Budget | Before | After |
|---|---|---|
| `MAX_AUTO_MERGE_TRANSIENT_RETRIES` | 3 | 5 (backoff
5s/10s/20s/40s/80s) |
| `MAX_TRANSIENT_MERGE_RECOVERIES` | 2 | 5 |
The bump broke two suites that had hardcoded the old `3`. Rather than
swap in another magic number, both now derive the cap from the constant
so future tuning doesn't re-break them.
## Verification
- `pnpm test:gate` green · `pnpm lint` clean · engine + ACP typecheck
clean · `pnpm verify:fast` PASS (5/5)
- ACP plugin 230 tests green · Grok plugin 64 green · engine
transient/merge suites 136 green
- Regression tests assert the **invariant across every surface** (per
*Fix the Invariant, Not the Repro*), not just the reported Grok string:
both ACP runtime prefixes, all retryable/non-retryable rpc codes, both
SDK error shapes, network delegation, class-ordering, and negative cases
proving bare `"Internal error"` and real defects stay permanent.
- A test caught a genuine bug in my own code mid-review (nested-shape
message shadowing), now fixed.
- `notifier.test.ts > "awaiting approval"` fails — **confirmed
pre-existing on clean main**, unrelated.
## Note
FN-8004's own branch (`fusion/fn-8004`) is still unmerged and its work
looks complete. Once this lands, its merge should be retried separately.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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