enhancement: `cora dead-code` ~82% false positives on framework-called methods (Phaser/SvelteKit); needs symbol-level skip

[ajianaz]

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cora dead-code reports 261 symbols on a SvelteKit + Phaser + Rust/Axum project. Manual triage shows ~82% (213/261) are false positives — methods invoked by frameworks via string/attribute registration, not explicit calls. The current skip mechanism (index_skip_files, added in v0.11.1 via #447) is file-level only and cannot suppress individual lifecycle methods without removing all symbols from the file.

Breakdown (261 total)

Category	Count	Why flagged	Reality
Phaser scene methods (create, init, update, preload, *Scene class methods)	155	no explicit caller	called by Phaser Scene registry
Rust route handlers + error mappers (login, me, health_check, submit_progress, bad_request, …)	41	no explicit caller	wired in build_router (Axum)
SvelteKit route exports (load, entries, GET/POST in +page.ts/+server.ts)	12	no explicit caller	framework-called
Test helpers	4	no explicit caller	test runner
Svelte template-only utils (cn)	1	no explicit caller	used inside .svelte markup

After removing genuinely dead code, only ~48 candidates remained for review.

Current mitigations (insufficient)

• --include-tests, --min-lines N — CLI flags only, not persistent.
• rules_engine.index_skip_files (fix: add skip list for index scanners to reduce false positives on entry-point files #447) — file-level glob, can't target a single method inside a normal source file (skipping ularTanggaScene.ts also hides its real call graph).
• Detect HTTP routes as graph symbols #438 (Detect HTTP routes as graph symbols) — will fix the Rust subset once shipped, but not Phaser/SvelteKit lifecycle.
• v0.11.0 — Intelligent Rules (Tier 2) #445 / Epic: Dead Code Detection #426 exclusions cover main(), #[entry_point], exported functions, tests, trait impls — not framework lifecycle methods.

Proposed

Framework-aware "called by framework" detection, plus a symbol-level escape hatch:

1. Phaser: methods on classes extending Phaser.Scene (create, init, preload, update) → mark as entry points.
2. SvelteKit: exports of +page.ts / +layout.ts / +server.ts (load, entries, GET, POST, …) → entry points.
3. Svelte actions: functions used as use:foo in .svelte markup → recognized as called.
4. Symbol-level suppression marker (parity with the file-level skip in fix: add skip list for index scanners to reduce false positives on entry-point files #447): support // cora: keep / // cora:inline comments, or reuse Rust's #[allow(dead_code)] / TS // eslint-disable style markers that cora already understands.
5. Config knob in rules_engine, e.g. entry_point_methods: ["Phaser.Scene::create", "Phaser.Scene::init", ...] with sensible framework defaults.

Environment

• cora 0.11.1