feat: Persist a durable retry marker and failed-attempt stderr when the

[andrei-hasna]

Objective

Persist a durable retry marker and failed-attempt stderr when the loops executor retries a Codewith agent

@hasna/loops retries a Codewith agent that fails fast at start, but nothing durable records that the retry happened, so a run that needed three attempts is stored as a plain success and a worsening transient failure is invisible.

Verified on origin/main. src/lib/executor.ts announces the retry only through an optional logger, at two sites (around lines 1241 and 1413):

opts.log?.(`retrying codewith agent after transient fast start failure (${attemptIndex + 1}/${CODEWITH_START_RETRY_DELAYS_MS.length + 1})`);

No production caller supplies log. Measured with a positive control so that an empty result is not mistaken for an empty set:

$ grep -rn "onSpawn:" src/ --include=*.ts | grep -v '\.test\.'
src/daemon/daemon.ts:252
src/lib/scheduler.ts:307
src/lib/workflow-runner.ts:276          <- the grep method does find real call sites

$ grep -rn "^\s*log:" src/ --include=*.ts | grep -v '\.test\.'
(no matches)                            <- nothing supplies the logger

Compounding it, each attempt allocates a fresh BoundedOutputBuffer for stdout and stderr (around lines 1156-1157 and 1324-1325), so the failing attempt's stderr is discarded when the next attempt starts.

Consequence: a run that succeeded on the third attempt is persisted as succeeded, carrying only the last attempt's output, with zero indication that two attempts failed first. This is not a false green — the work really did succeed — but on a runner that executes unattended work, "we silently papered over a failure N times" must stay visible. Otherwise the first observable symptom is the day the retries stop being enough.

Expected behaviour after the fix: when a retry fires, evidence of it survives the run and is visible to somebody reading the stored run afterwards, without a caller having to opt in to a logger.

Required:

• Persist a retry marker somewhere durable on the run: append it to the returned stderr, or record it on the run/receipt structure the executor returns. Whichever you choose, it must be present in what gets stored, not only in an optional callback.
• Carry the failed attempts' captured stderr forward rather than discarding it when the buffer is reset, so the reason each attempt failed is still readable. Respect the existing output-size bound — do not let carried-forward output grow unbounded; truncate within the existing maxOutputBytes budget.
• Apply the change to BOTH retry sites in src/lib/executor.ts; they are near-duplicates and fixing only one leaves half the paths silent.
• Keep the existing opts.log?.() call as well; this adds a durable record, it does not replace the logger.

Acceptance:

• A failing-first regression test that drives the executor through a simulated transient fast start failure followed by a success, and asserts (a) the returned/stored result contains a retry marker, and (b) the failing attempt's stderr text is still present in the output. Confirm the test fails before the change and passes after.
• A test asserting that a run which succeeds on the first attempt gains no retry marker, so the marker is not noise on the normal path.
• bun test, bun run typecheck and bun run build all pass.

Keep the change minimal and scoped to the retry accounting in src/lib/executor.ts. Do not change the retry policy itself, the delay table, the matcher that decides what counts as a transient fast start failure, or anything about how runs are scheduled.

Upstream issue: #143

Verification

• policy source: base 4461670 (immutable commit — agent-proof)
• containment: env — allowlist env, non-login shell, run-scoped HOME (registry auth seeded for install)
• install: pass
• typecheck: pass
• build: pass
• test: pass
• doctor (ci): ok — 11 checks passed (1 advisory)

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Run run_86c67f977070 · backend codewith · task 860bd291-40db-48cc-b168-ee0938e4b4c8
🏭 Generated by @hasnaxyz/factory

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