# B8-S1 Chain Completion — 8-commit cumulative effect

| Field | Value |
|---|---|
| Date | 2026-05-05 |
| main HEAD | `8e15019` |
| Verdict | **blocked** |
| Predicted top | verified (45%) / blocked (20%) |

## Setup

- worktree: `agent-ac78918a8709780d2` (clean, main HEAD `8e15019`)
- `.reyn/` flushed with `rm -rf`
- `reyn.yaml` temporarily modified: `python.trusted: allow` added (not committed)
- flag: `--allow-untrusted-python`
- trace dump: `REYN_LLM_TRACE_DUMP=$(pwd)/.reyn/llm_trace_b8s14.jsonl`
- stdin piped (non-TTY): subprocess + piped stdin, readline fallback active
- input: `skill_improver で direct_llm を 1 回 review して改善案を出して`
- total wall time: ~18s (no timeout)

## Observation

### Phase progression

| Phase | Reached | Result |
|---|---|---|
| router | yes | `invoke_skill(name="skill_improver")` — 1 turn, no list/describe calls |
| prepare | yes | 1 LLM call → `run_skill(eval_builder)` |
| analyze_skill (eval_builder sub-skill) | yes | 2 preprocessor steps completed, then 5 LLM turns with permission_denied on each |
| copy_to_work | NO | never reached |
| run_and_eval | NO | never reached |
| plan_improvements | NO | never reached |
| apply_improvements | NO | never reached |
| finalize | NO | never reached |

### dogfood_trace --mode chain (abridged)

```
[T+2.0s]  tool: invoke_skill(name="skill_improver", input={...})
[T+2.0s]  workflow_started: skill_improver  run_id=20260504T215345Z_skill_improver
  [T+2.0s]  phase_started: prepare
  [T+4.0s]  tool: run_skill(skill="eval_builder", ...)
  [T+4.0s]  run_skill_started: eval_builder
    [T+4.0s]  workflow_started: eval_builder
      [T+4.0s]  phase_started: analyze_skill
      [T+4.0s→T+10.0s]  preprocessor_step_completed x2 (python steps 0+1 OK)
      [T+10.0s→T+16.0s]  5 LLM turns: permission_denied on direct_llm/skill.md + artifacts/*.yaml each turn
      [T+16.0s]  control_decided: abort  (reason: "Failed to access required skill files")
      [T+16.0s]  workflow_aborted: eval_builder
    [T+16.0s]  control_ir_failed: run_skill (LLM aborted analyze_skill)
  [T+16.0s]  prepare aborts: "analyze_skill phase aborted due to permissions"
[T+17.0s]  skill_run_failed: skill_improver
[T+18.0s]  router delivers clean failure message to user
```

### LLM calls

Total: 9 calls (1 router + 1 prepare + 5 analyze_skill + 1 prepare-abort + 1 router-final).
All `finish_reason=stop` with non-empty content. Zero empty stops.

### Router behavior change vs B7-S1

In B7-S1 fresh retest, the router used 5 turns (list→list→describe→describe→invoke).
In B8-S1, the router used **1 turn** → direct `invoke_skill(name="skill_improver")`.
This suggests the router enum fix + system prompt skill list encoding now allows 1-shot invocation
for a well-known skill name from user input.

### Stopping point vs B7-S1

| Session | Stopping phase | Reason |
|---|---|---|
| B7-S1 fresh retest (eeb8ed9) | copy_to_work preprocessor step[1] | file.read permission_denied on stdlib path |
| B8-S1 (8e15019) | analyze_skill (eval_builder sub-skill) | file.read permission_denied on stdlib path |

The stopping point has **moved earlier** in the chain: `analyze_skill` (inside `eval_builder`,
called by `prepare`) fires before `copy_to_work` can start. In B7-S1, `analyze_skill` had a
`PureModeViolation` (B8-NEW-2) that aborted it silently before reaching file reads. In B8-S1,
B8-NEW-2 is fixed — `analyze_skill` now runs its LLM turns — but immediately hits permission_denied
on the same stdlib path that blocked `copy_to_work` in B7-S1.

### Failure mode detail

```
permission_denied events: 18 total
  - direct_llm/skill.md: 8 denied (4 turns × 2 skills [skill_improver + eval_builder contexts])
  - direct_llm/artifacts/*.yaml: 8 denied
  - direct_llm/eval.md: 2 denied (final turn)
```

The permission system is blocking `eval_builder.analyze_skill` from reading
`src/reyn/stdlib/skills/direct_llm/` files. This is the same root cause as B8-NEW-1 but manifests
earlier now that B8-NEW-2 (PureModeViolation) is fixed.

### user-visible output

```
skill_improver は direct_llm スキルを改善できませんでした。原因は、skill_improver が
スキルファイルにアクセスする権限がないことです。
```

Improvement suggestion: **not delivered**. Finalize never ran.

## Verdict reasoning

`blocked`: The 6-phase chain (`prepare → copy_to_work → run_and_eval → plan_improvements →
apply_improvements → finalize`) did not complete. Chain stopped at `analyze_skill` (eval_builder
sub-skill called from `prepare`). Root cause is the same permission_denied on stdlib skill files
as B8-NEW-1, now surfacing one step earlier due to B8-NEW-2 fix.

Prediction was 45% verified, 20% blocked. Actual: blocked. The blocker was accurately in the
prediction distribution but at the low-probability end.

## Implications

- B8-NEW-1 (stdlib file.read permission_denied) remains the primary chain blocker. The fixing of
  B8-NEW-2 (PureModeViolation) exposed the real path — `analyze_skill` LLM turns now run and
  immediately hit the same permission wall.
- A fix to eval_builder's permissions frontmatter (or OS automatic approval of stdlib paths in
  `run_skill` isolated context) would unblock this path.
- Router improvement: 1-turn direct invoke_skill in this run vs 5-turn in B7-S1. This is a
  positive improvement worth monitoring — may be environment/state dependent.
- batch 9 priority: fix B8-NEW-1 (stdlib read permission in run_skill isolated context) to
  allow chain to progress to `copy_to_work`.
