refactor(verification): weaken inv_field_001 axiom to document-level preservationFriendly (rebased follow-up to #208)#220
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stevenobiajulu merged 2 commits intoMay 22, 2026
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…nt-level preservation friendliness Closes peer-review concern D (predicate strength) from PR #208. Codex review confirmed the current engine satisfies the stronger `∀ ctx` predicate, but the ECMA-376 Part 4 deep-research report showed that a conformant emitter MUST fragment fields across wrapper boundaries when modifying a field — fragmented `<w:ins>`/`<w:del>` wrappers containing only `w:instrText`/`w:delInstrText` are NOT `fieldContextNeutral` under `∀ ctx`. When safe-docx becomes ECMA-376-conformant (tracked in #217), the stronger predicate will break. This commit weakens the residual axiom to be future-compatible without touching the engine. ## Predicate weakening Adds `Tier2.AcceptReject.preservationFriendly` — a document-level property asserting only that accept and reject preserve the *composed* field walk and begin/end balance. Strictly weaker than the previous per-subtree `Tier2.FieldStructure.recursivelyWellformed`: * Old: `validateFieldStructure d ∧ ∀ wrapper-subtree, fieldContextNeutral subtree` where `fieldContextNeutral bs := ∀ ctx, walkBlocks (.ok ctx) bs = .ok ctx`. * New: `validateFieldStructure d ∧ walkBlocks (.ok []) (acceptBlocks d.blocks) = walkBlocks (.ok []) d.blocks ∧ ...` (analogous for reject + balance). The old predicate is retained in `Tier2.FieldStructure` and the legacy `field_structure_preserved` lemma still compiles — they remain available for audit traceability. Only `inv_field_001` is rewired to consume the new predicate via the new `Tier2.InvFieldOne.field_structure_preserved_doc` lemma. ## Axiom replacement `Spec.lean` replaces `compareDocumentXml_output_recursivelyWellformed` with `compareDocumentXml_output_preservation_friendly`. The `inv_field_001` proof body changes to compose the new axiom with `field_structure_preserved_doc`. `#print axioms LeanSpike.inv_field_001` becomes: [propext, compareDocumentXml, compareDocumentXml_output_preservation_friendly, Quot.sound] ## TS bridge — explanatory comment The existing `isFieldContextNeutral` / `assertRecursivelyWellformed` checks in `lean-spec-bridge.test.ts` enforce the OLD stricter property. With the axiom now weaker, these become an audit OVER-check: the engine currently satisfies them (whole-field wrapping), but when #217 lands and the engine starts fragmenting, these checks will need to be removed or relaxed. The comment block above the field-bearing fixtures is updated to reflect this layering. Ref: #208, #217
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…ture (currently catches #217 engine non-conformance) PR #208 added a deleted-NUMPAGES bridge fixture that calls `assertRecursivelyWellformed(result.combined)`. Independently, PR #211 tightened `validateFieldStructure` to reject `w:fldChar` inside `<w:del>` (per ECMA-376 Part 4 — Word treats this as fatal). Both PRs squash-merged to main within 4 seconds of each other; PR #208's CI passed against the pre-#211 validator, so the interaction wasn't caught. The current engine emits deleted complete fields as a single `<w:del>` containing the entire begin/instrText/separate/result/end run sequence (`inPlaceModifier.ts:938`) — that is, with `w:fldChar` inside `<w:del>`. The engine's own safety check at `pipeline.ts:439-440` only validates the post-accept and post-reject outputs (which ARE conformant: accept drops the `<w:del>` entirely; reject unwraps to a complete field). PR #211's tightening therefore does not affect the engine's safety check, but it does affect manual calls to `validateFieldStructure` on the combined XML — which is exactly what `assertRecursivelyWellformed` does. Net: main is currently broken on `workspace-test` because the deletion fixture's `assertRecursivelyWellformed` call fails. This commit removes that call from the deletion fixture and replaces it with a TODO comment referencing #217. The fixture still exercises the `w:delInstrText` atom case via `assertFieldInvariant` (which checks the engine's own consequence: `validateFieldStructure` on accept/reject outputs). The over-check can be re-enabled when #217 lands and the engine fragments fields per ECMA-376. The renamed test description reflects the actual asserted property. Ref: #217 (engine fragmentation conformance — the long-term fix). Ref: #208 (which introduced the fixture), #211 (which tightened the validator), #220 (which lands the axiom weakening; this commit fixes the test break).
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Post-merge smoke test ✅Smoke tested on main at Tests re-run (cited in PR #220 and its predecessors #208, #211):
Runtime probe — Proves the merged module's export surface still exercises the PR #211 tightening that PR #220 had to dance around ( Notes:
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Summary
Follow-up to #208. Same content as the now-superseded #219 (which had merged into the stacked PR-A branch but not main). Cherry-picked onto current main.
Replaces the load-bearing residual axiom in `Spec.lean` from the per-subtree `Tier2.FieldStructure.recursivelyWellformed` (which requires `∀ ctx` neutrality of every track-change wrapper subtree) to the new document-level `Tier2.AcceptReject.preservationFriendly` (which only asserts that accept and reject preserve the composed walk and begin/end balance).
The new predicate is strictly weaker than the old one and is future-compatible with ECMA-376 field fragmentation (#217). The old predicate happens to hold for the current safe-docx engine — Codex's review of #208 confirmed via `inPlaceModifier.ts:717, 938, 1505, 1671, 1957, 2300` that the engine emits whole field sequences as single track-change wrappers. But when #217 lands and the engine starts fragmenting per ECMA-376 Part 4, the old `∀ ctx` predicate breaks while `preservationFriendly` still holds.
This PR lands the predicate weakening before the engine refactor so the Lean side never has to live with a known-broken axiom.
What changed
Test plan
Why a new PR (not retargeting #219)
#219 was a stacked PR targeting `worktree-inv-field-001-proof`. When #208 squash-merged to main and #219 squash-merged into the now-stale worktree branch (within seconds of each other), the chain collapsed and #219's content never made it into main. This PR is the clean re-land against current main.
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