Bug: `acpx` exit 5 (PERMISSION_DENIED) fails the whole run even though the turn ended with valid JSON

[jic-cc]

Repro (backpass 0.1.18 · acpx 0.13.2 · claude-agent-acp ^0.60 · analysis pinned to claude/claude-sonnet-5):

1. The distilled trace ends with the raw transcript path (as designed).
2. The analysis agent runs grep -o ... <raw transcript>.jsonl through Bash instead of an ACP read.
3. --approve-reads only approves ACP read/search kinds, so the request is denied. The agent continues, finishes the turn with stopReason: end_turn and a complete JSON answer (8,905 output tokens in our stream).
4. acpx sets exitCode = PERMISSION_DENIED (5) because a request was denied; backpass treats non-zero as session prompt failed and aborts the whole pass:

error pinned analysis agent claude (claude-sonnet-5) failed unexpectedly (acpx claude session prompt failed (exit 5): [acpx] tokens: input=4 output=8905 cache_read=108206 cache_write=62154 total=179269)

Expected: a denied request with a completed turn is a warning (the answer is still evidence; the model just did not get to open the raw file), not a fatal error. Suggested: treat exit 5 as success when stdout parses as the expected JSON, and surface deniedRequests: N in the evidence file. A re-run passed only because the model did not grep the second time.

Minor, same area: the cross-surface report flagged five CLAUDE.md restates <skill> body · 1 tok · similarity 1.00 entries. A 1-token overlap at similarity 1.00 is a separator line, not a restatement; a minimum unit size would remove the noise.

[kunchenguid]

Speaking as Kun's firstmate.

VISION per-rule (brief): Evidence currency — aligns (keep parseable analysis JSON as evidence when the turn completed). Human owns weights — n/a. Nothing on faith — aligns (trust measured stdout parse, not acpx's blanket non-zero). Budget — n/a. Owns nothing — n/a. Failure loud/named — aligns (denied Bash grep should be a named warning with deniedRequests, not a silent abort of a finished turn; also the 1-tok similarity=1.00 cross-surface noise is a measurement defect). Scope — aligns (adapter/root fix in acpx invoke path).

contract-class: restore (unconfigured analysis already promises usable evidence when the agent finishes a turn; aborting on exit 5 after valid JSON breaks that path).

Verified on latest main (713c3629): src/acpx.js session prompt throws on any result.code !== 0 before reading stdout; classifyAcpxFailure does not special-case PERMISSION_DENIED. Reporter's exit-5 + valid JSON path matches. Labeling ready-for-pr.

[kunchenguid]

Speaking as Kun's firstmate:

Stale-restamp (still-real pass). Re-checked latest main 376b906 (2026-09-19).

VISION per-rule: Evidence currency — aligns (keep parseable analysis JSON as evidence when the turn completed). Human owns weights — n/a. Nothing on faith — aligns (trust measured stdout parse, not acpx's blanket non-zero). Budget — n/a. Owns nothing — n/a. Failure loud/named — aligns (denied Bash grep should be a named warning with deniedRequests, not a silent abort of a finished turn; 1-tok similarity=1.00 cross-surface noise is a measurement defect). Scope — aligns (adapter/root fix in acpx invoke path).

contract-class: restore (unconfigured analysis already promises usable evidence when the agent finishes a turn; aborting on exit 5 after valid JSON breaks that path).

Fixed on main? No. src/acpx.js session prompt still throws on any result.code !== 0 before reading stdout; classifyAcpxFailure does not special-case PERMISSION_DENIED / exit 5. No deniedRequests surface found. Open PRs #138/#129/#128 do not address this. No linked helping PR.

Leaving ready-for-pr. Not pinging the author.