chimera-carry-the-failure-forward
A retry loop that overwrites its feedback variable shows attempt 3 only the failure of attempt 2 — so it re-derives the patch attempt 1 already tried.
Conferred by a reviewer who read the card, not claimed by the file about itself. A card the agent distils during a run that consumed untrusted content is born tainted and is held for review before it is ever retrieved.
When it comes to mind
- writing a retry loop
- the agent keeps trying the same fix
- feeding verifier output back to the model
- attempts keep failing the same way
- reverting the workspace between attempts
Avoid and Check are where the value usually is. Do is the section everybody writes.
Trigger
You have a loop that runs an attempt, judges it, and runs another one with feedback: an agent with a verifier, a code fixer against a test suite, a generate-and-check pipeline. The budget is more than two attempts, and the workspace is reverted between them so each attempt starts clean.
It does not apply to an idempotent retry over a flaky transport — a network call that failed for reasons unrelated to what you sent. There is nothing to learn from attempt 1 there, and carrying it forward is just payload.
Do
- Store attempts in a list, not in a variable you reassign. One record per attempt: the verifier output, the patch the attempt actually wrote, and which tool step errored first.
- Take the patch from the workspace snapshot, before the revert — the real diff, not the model's description of what it changed. The revert is what makes this necessary: once the tree is rolled back, nothing on disk records the wrong path either, so the next attempt has no obstacle to re-deriving the same one.
- Compose the retry prompt from every record, oldest first, each labelled with its attempt number and its verdict, under a heading that says these were already tried and reverted.
- Bound each record. Chimera caps a fed-back diff at 2000 characters and truncates with a marker; an unbounded three-attempt history will dominate the prompt.
- Deduplicate by failure signature. If two attempts failed the same way, keep one and record that it recurred — the repetition is the signal, the second copy is not new information.
- When the signature repeats, stop appending and change something structural: re-plan with the
accumulated causes as planner context (
TaskLedger.context()renders them under "Why earlier attempts failed (do NOT repeat these):"), or escalate to a stronger model. More feedback about the same dead end does not leave the dead end. - Emit a countable event each time you inject history, so a benchmark arm can prove the injection fired at all.
Avoid
The overwrite. In chimera/core/autonomous.py the loop's feedback is rebuilt each round:
feedback = "\n\n".join(p for p in (fb, _verify_fb) if p) or "The attempt did not pass verification."
so attempt 3 is composed with attempt 2's failure and nothing from attempt 1. Carrying it forward means appending to a structure instead — sketched, not quoted, because the accumulating version is what this card argues for rather than what the file currently does:
records.append(record_for(index, verdict, patch)) # one entry per attempt
feedback = render(records) # every attempt, oldest first
Be precise about which half is already there when you read this in Chimera: the content of the
feedback is well covered — --diff-feedback shows the retry the patch it actually wrote
(chimera/core/autonomous.py, capped at _DIFF_FEEDBACK_MAX_CHARS = 2000), and TaskLedger
accumulates causes for the planner. What is not covered is the accumulation across attempts in the
line above. A card that presented all of it as missing would be arguing against work already done.
Also avoid telling the retry that it failed without showing what it wrote. "The attempt did not pass verification" plus a failing test is enough to make a model try again and not enough to make it try something different — the wrong patch is invisible to it and the workspace no longer contains it, so re-deriving it is the path of least resistance.
And avoid carrying only the manager's prose while dropping the verifier's output. The failing assert is the most actionable line in the whole loop; a reviewer's paragraph about it is a paraphrase of strictly less information.
Check
Instrument the composer, run a task you know fails three times, and grep the attempt-3 prompt for a string that exists only in attempt 1 — a filename it touched, an identifier from its diff. Present or absent; there is no partial credit.
Second check, equally binary: count the injections. A run where the history was never assembled because the guard was wrong, or because the diff list was empty, measured nothing at all — and a benchmark arm built on that measures the plumbing, not the idea. If the counter reads zero, the result is void regardless of what the success rate says.
Risk
Anchoring is the registered counter-hypothesis, not a hypothetical: showing a model the wrong patch
can fix its attention on that patch and produce variations of a dead approach instead of a different
one. This is why the behaviour is opt-in and measured in Chimera (--diff-feedback) rather than
turned on by default. Treat it as a claim to test on your own tasks, not a settled improvement.
The second cost is the context budget. Three diffs, three verifier dumps and a manager review can push the prompt past its compaction threshold — and then a compactor with no restoration will drop exactly the accumulated history you paid to build. Bound the records and know your budget before enabling this, or the two mechanisms will fight and the visible symptom will be neither of them.
Use it
The card is data. Clone the repository and import it by path — anything that arrives over the network is treated as tainted and held for approval, which is the behaviour you want and the reason there is no one-line installer here.
git clone https://github.com/brcampidelli/chimera-agent.gitchimera skills-import chimera-agent/skills/chimera-carry-the-failure-forward/SKILL.mdIntegrity
SHA-256 of the file as published. An importer can check that what it received is what this page showed.
62dcc2aa830e5eb35c554bebf2c1a24454a054bf17bf152ccd59f3497b5e043d