Date: 2026-09-02. Private runs 20260902T054015Z-0e51db and
20260902T054112Z-ae9e1b. Sanitized from local evidence.
Until these two runs, the revision cycle, the second review, and every blocking path had unit coverage and no live evidence. Both runs used Codex as primary and Claude as reviewer against disposable local fixtures.
The clamp fixture. clamp(value, low, high) silently swaps inverted bounds.
The issue demanded that clamp raise ValueError when low > high, and in the
same breath declared test_swapped_bounds_are_swapped, which asserts
clamp(5, 10, 0) == 5, a supported guarantee that must keep passing unedited.
Those two requirements cannot both hold. Real issues contain contradictions like
this, usually less obvious.
| Stage | Result |
|---|---|
| Primary, Codex | exit 0 in 55.1s, report present, no change made |
| Verification after primary | exit 0 in 0.09s |
| Reviewer, Claude | exit 0 in 52.4s |
| Verdict | REVISE |
| Revision, Codex | exit 0 in 77.8s, clamp.py changed, new test file added |
| Verification after revision | exit 1 in 0.08s |
| Final status | BLOCKED after one revision |
Codex diagnosed the contradiction and deliberately changed nothing, saying so in
its report. Claude confirmed the workspace was still at the base commit, ran the
tests itself, and named the contradiction independently. On the revision Codex
implemented the issue's requirement and predicted, correctly, that the mandated
test would fail. It added test_clamp_invalid_bounds.py rather than editing the
test it was told not to touch.
Every agent behaved well. The run still ends BLOCKED, which is the right
ending: the request cannot be satisfied, and no patch should reach a human
carrying an implicit "we broke a test you said to keep".
The verification after the primary stage passed because nothing had changed. A green check and an untouched workspace looked identical in the record. The loop now records the changed paths after each primary stage, so the evidence distinguishes work from no work. The reviewer, not the harness, is what caught it here.
The shorten fixture. shorten(text, limit) sliced to limit and then appended
a three-character ellipsis, so every truncated result overshot by three. One
existing test failed at the base commit. The issue also asked, in a closing
note, for truncation to stop at a word boundary. No test covered that.
| Stage | Result |
|---|---|
| Primary, Codex | exit 0 in 90.0s |
| Verification after primary | exit 0 in 0.09s |
| Reviewer, Claude | exit 0 in 104.3s |
| Verdict | REVISE |
| Revision, Codex | exit 0 in 78.2s |
| Verification after revision | exit 0 in 0.08s |
| Second review, Claude | exit 0 in 80.5s |
| Verdict | APPROVE |
| Final verification | exit 0 in 0.08s |
| Final status | READY_FOR_HUMAN_REVIEW, 1 revision, 2 review cycles |
The first attempt fixed the length bug and attempted the word boundary with
max(..., default=-1), which conflates "no space found" with a valid index, so
prefix[:-1] trimmed exactly one character instead of dropping the partial word.
The tests passed anyway: the one new boundary case landed on a position where
the character was already a space, so it never exercised the new code.
Claude found it by running the function, not by reading it:
shorten(SENTENCE, 5) -> 't...'
shorten('abcdefgh', 6) -> 'ab...'
It named the root cause, and separately noted the test that did not test
anything. Codex changed the fallback to 0, added the two cases that do
exercise the path, and pushed back on one of the reviewer's suggested
expectations with the arithmetic showing it exceeds the limit. The second review
ran the suite again, traced the boundary arithmetic by hand, and approved.
The bounded loop's remaining paths now have live evidence: one revision, a
second review, an approval after a revision, and a run that ends BLOCKED
because independent verification failed.
They also show the reviewer earning its place twice. In the first run it caught an empty candidate that verification had waved through. In the second it caught a fix that passed the tests and was still wrong.
Codex could not run the pinned interpreter in either run and said so both times, so the primary's exit code carried no engineering information in any live run to date. Two fixtures, one language, one file each. The other blocking causes, a missing or contradictory verdict, an agent timeout, an agent that produces no report, still have only unit coverage.