perf: cache _source_key and make _walk_python_tree iterative

[EinWenigDaneben]

What

Two extraction-path performance improvements.

1. Cache _source_key filesystem resolution (graphify/extractors/resolution.py) — memoize on (source_file, root), cleared once per extract() run; skips repeated stat/realpath syscalls per node/edge/raw_call.

2. Iterative _walk_python_tree — replace the recursive generator (yield from re-forwards every descendant through the call chain, O(depth) per node) with an explicit-stack pre-order walk; each node yielded exactly once. Same node order.

Evidence

Single-worker extract on a 357-file PHP corpus, best-of-3:

	min
baseline (no patch)	2.20 s
with patch	1.18 s

~46% faster on the measured corpus.

Tests

tests/test_hermes_verified_optimizations.py locks pre-order identity of the iterative walk + _source_key memo stability. Rest of the suite: only pre-existing failures (test_skillgen, test_ollama_retry_cap) which also fail on unpatched v8.

[graphify-labs]

Graphify reviewed this change.

Looks safe to merge — no coupling regressions and no blocking issues, checked against the code graph (not a self-assessment).

Formal verification. 1 change(s) tested, no difference found (not proven).

---

Graphify review — findings

This PR applies two performance-oriented changes in the resolution extractor. It adds a module-level _SOURCE_KEY_CACHE memo to _source_key (keyed by source_file and root) and clears it at the start of each extract() run, and it rewrites _walk_python_tree from a recursive yield from generator into an iterative explicit-stack pre-order DFS. It also adds a new test file (test_hermes_verified_optimizations.py) that checks the iterative walk matches the previous recursive traversal order and that _source_key memoization returns stable results and populates the cache. The changed-symbols list is broad, but the actual diff touches only extract.py, resolution.py, and the new test file.

No blocking issues surfaced. 1 lower-confidence candidate did not survive cross-model review.

Analysis details — impact, health, verification

Impact & health

Graphify review

Impact — 1654 functions depend on the 334 functions this change touches.

Health — this change adds coupling hotspots:

• new: extract() — 454 callers, 41 callees
• new: _rebuild_code() — 95 callers, 51 callees
• new: _extract_generic() — 18 callers, 23 callees
• new: extract_xaml() — 19 callers, 17 callees
• new: extract_objc() — 27 callers, 9 callees
• new: dispatch_command() — 2 callers, 117 callees
• new: extract_js() — 76 callers, 3 callees
• new: _resolve_js_module_path() — 27 callers, 6 callees
• …and 38 more

Verification — 1654 functions in the blast radius were not formally verified this run (proofs are advisory here).

Gate & verification

graphify gate

PASS — objectively clean (no health regressions, tests not run — proofs not run this pass (advisory)). Grounded, not self-assessed.

Advisory (not blocking):

• verification_scope: 1514 function(s) in the blast radius were not formally verified this run

Formal verification

Could not verify: Could not verify extract.

The verifier did not have enough to check extract, so it is saying so rather than guessing. No false assurance is the whole point.

Guarantee: No guarantee either way, this is an honest abstention, not a pass.

Note: Reason: parameter `cache_root` is annotated `Path | None` — outside the synthesizable primitive/collection set

Could not verify: Could not verify \_source\_key.

The verifier did not have enough to check \_source\_key, so it is saying so rather than guessing. No false assurance is the whole point.

Guarantee: No guarantee either way, this is an honest abstention, not a pass.

Note: Reason: parameter `root` is annotated `Path` — outside the synthesizable primitive/collection set

No difference found (not proven): No behavior difference found in \_walk\_python\_tree (not a proof).

The verifier ran both versions of \_walk\_python\_tree on many inputs and saw identical behavior every time. Strong evidence the change is safe, but evidence, not a proof.

Guarantee: Empirical: concolic exploration (CrossHair). A divergence on an untested input remains possible, so this is 'no counterexample found', not 'proven equivalent'.

Note: An input the sampler did not try could still differ.

· 46 more finding(s) on lines outside this diff (see the check run).