evo-mutation-rollback · diff
git:20261003.980fb6a to git:20261026.587ad32
48 added, 20 removed. Audit A to A.
---
name: evo-mutation-rollback
- description: Safe propose, evaluate, select, revert sequence for Evo mutations with no irreversible steps.
- keywords: [rollback, revert, mutation, regression, snapshot, candidate]
+ description: Safe propose, evaluate, select, revert discipline for Evo mutations — snapshot the working tree, mutate one concern, gate on deterministic fitness, and commit or atomically roll back.
+ keywords: [evo, mutation, rollback, fitness, candidate, revert, optimize]
---
# Evo Mutation Rollback
- A mutation is only safe if it can always be undone. Never let a budget,
- timeout, or failure land on a step you cannot roll back.
+ A mutation is only safe if it can always be undone. Nothing is committed
+ until a deterministic fitness gate has passed, and a regression never
+ leaves the tree dirty.
## Sequence
- 1. `evo_propose_candidate` — snapshot the target files FIRST. This is the
- rollback anchor; nothing is mutated until this succeeds.
- 2. Apply the mutation to the working files.
- 3. `evo_evaluate_candidate` — run the verification command and read the
- fitness score plus the compact failure digest.
- 4. Decision:
- - Fitness improved and tests pass -> `evo_select_candidate` (commit to
- the lineage DAG).
- - Fitness regressed, tests failed, or the digest shows a real bug ->
- `evo_revert_candidate` (restore the snapshot exactly).
- 5. Confirm the revert restored the original file contents before continuing.
+ 1. **Baseline & Snapshot Verification** — Confirm the working tree is
+ clean before mutating:
+ - `git_status` → must report no pending changes (this is the
+ rollback anchor; if the tree is dirty, stop and reconcile first).
+ - `git_diff` → must be empty; record any intentionally pre-staged
+ context.
+ - Record the **baseline fitness score** (the current
+ test/benchmark result for the metric under optimization) and the
+ **exact list of target files** the mutation may touch.
+ 2. **Surgical Single-Concern Mutation** — Apply the mutation strictly to
+ the declared target files, using:
+ - `ast_replace` — preferred for structural (syntactic) changes; it
+ performs in-memory AST validation and rolls back automatically on
+ a syntax error, so a failed mutation never dirties disk.
+ - `edit_file` — for exact-substring edits; likewise AST-validated
+ before the on-disk commit.
+ Never edit a file that is not on the target list — changes outside
+ the list are not covered by the rollback.
+ 3. **Deterministic Fitness Gate** — Run the verification command via
+ `bash`. Use exactly the gate appropriate to the workspace:
+ - `cargo test --all-features`
+ - `cargo clippy --all-targets --all-features -- -D warnings`
+ - `castor evo run` (for the repo's own Evo task suites)
+ Capture the fitness score and the compact failure digest (see the
+ `traceback-condensing` skill — never paste raw multi-page output).
+ 4. **Selection or Atomic Rollback** — Decide on the digest:
+ - **Select**: fitness strictly improved (or held neutral on an
+ explicit simplification pass) with **zero regressions**. Commit
+ the candidate via `git_commit(paths: [...])` listing exactly the
+ mutated files.
+ - **Rollback**: fitness regressed, any test failed, or the digest
+ shows a real bug. Immediately restore the touched files via
+ `bash`: `git checkout -- <paths>`, then confirm a clean tree via
+ `git_status` before continuing.
+
## Rules
- - The snapshot (step 1) must always precede any file mutation.
- - If a step is interrupted by a timeout or budget, the next action is to
- revert to the last good snapshot, not to resume mid-mutation.
- - Never edit a file that is not in the candidate's snapshot list; those
- changes are not covered by the rollback.
+
+ - The snapshot verification (step 1) must always precede any file
+ mutation; an interrupted mutation is rolled back, never resumed
+ mid-edit.
+ - Never batch multiple concerns into one candidate — the fitness delta
+ must be attributable to a single change.
+ - If a step is interrupted by a timeout or budget, the next action is
+ to roll back to the last good state, not to resume mid-mutation.