pre-push(17.4): a file new in head is new, not comparison unknown

ChangeContext records the paths Git reports as added. An entailed,
undischarged operation in an added file, with complete head evidence and no
identical operation in any base answer, is classified new
(file_added_in_head) instead of base_incomplete; admission accepts that reason
as change evidence. Unpaired add/delete pushes and every other unknown
comparison keep their vetoes. An engine finding whose novelty is established
and whose only vetoes are capability vetoes is shown as an advisory engine
finding, not an alert. Requirement 9.4.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01EmM1j46qgKMh3zqD1QMwEo

.kiro/specs/pre-push-safety-net/tasks.md

@@ -642,10 +642,11 @@ Preserve all completed task evidence below.
   - Evidence: serve-static's planted `eval` in the new `debug.js` is shown; whether records' planted `%`-formatted SQL is shown is recorded as is, with no rule edits for it.
   - _Done 2026-10-02:_ new `push/quick.py` runs the shipped quick rules (no shadow rules, no model) over the changed head files inside `_prepare` under the shared deadline, before the engine, keeping matches on a changed line or inside a changed function (entry-point ranges); it records `files`/`bytes_read` as proof of input. The terminal shows them under "Quick rules: N pattern match(es) on changed code ... Advisory: not verified by the engine."; the artifact keeps `quick_tier`; admission and push disposition are untouched. A new branch runs the quick tier over its last commit's changes and says so. `_analyze` gained `engine="off"`. On the audit's serve-static planted commit the `eval` in the new `debug.js` is now shown (js-eval, js-xss-response at debug.js:2, ~1.1 s on the host); the planted `%`-formatted SQL in records is NOT matched by any quick rule (coverage gap, no rule edited). Tests: `tests/test_push_quick.py` (3). Gates: 1998 passed, 42 skipped; ruff, format, mypy clean.
   - _Requirements: 9.3_
-- [ ] 17.4 Classify a file new in head as new, not unknown
+- [x] 17.4 Classify a file new in head as new, not unknown
   - `ChangeContext` records the paths Git reports as added. An operation in an added file, when no add/delete pairing is unresolved and its head evidence is complete, is `new` with reason `file_added_in_head`, and admission accepts that reason as change evidence. An engine finding with established novelty whose only vetoes are capability vetoes renders as an advisory engine finding, not an alert. Every other unknown comparison keeps its veto.
   - Files: `src/openultrasast/model/contracts.py`, `src/openultrasast/push/snapshot.py`, `src/openultrasast/push/policy.py`, `src/openultrasast/push/report.py`. Tests: `tests/test_push_policy.py`, `tests/test_push_snapshot.py`, `tests/test_push_report.py`.
   - Evidence: unit tests on the comparison and admission; a live engine run if the host allows one (free memory >= 3 GB).
+  - _Done 2026-10-02:_ `ChangeContext.added_paths` records Git status-A paths (rename targets excluded). In `_compare_evidence`, after every existing context/head/deadline check, an operation in an added file is `new`/`file_added_in_head` when the claim is entailed, undischarged and has change evidence, and no base answer holds the same operation (else `operation_moved_within_change`); an unpaired add/delete still blocks as `change_context_unresolved`. Admission accepts `(new, file_added_in_head)`; with the empty registry such a candidate's only veto is `capability_unavailable`, and the terminal now shows it under "Engine: N finding(s) this push introduced. Advisory ... not an alert." Any comparison, evidence or location veto keeps a candidate out of that line. Tests: `tests/test_push_new_file.py` (9). Live engine evidence depends on host memory (17.7). Gates: 2007 passed, 42 skipped; ruff, format, mypy clean.
   - _Requirements: 9.4, 3.4_
 - [ ] 17.5 Say when the engine cannot finish, and offer it in the background
   - One line when the engine did not finish (deadline, engine not installed). `--engine background` starts the engine detached after the quick tier, writes its result under the artifact directory and, on the next run, prints "engine result for <head> from the previous push". One background engine at a time; `--engine off` skips it with a stated line. No speed work.