fix(roles): stop emitting dead-* verdicts for declarative-only languages (#2385)

[carlos-alm]

Summary

For languages where call resolution is intentionally absent (Terraform/HCL), role classification emitted dead-unresolved for every symbol — a 100% false-positive verdict by construction, since HCL has no functions, classes, or call graph at all: every node always has fanIn === 0 regardless of how many times a resource is actually referenced elsewhere in the same file (only reference-tracking, not call-tracking, would show that — and HCL produces no reference edges either). This invites destructive action: an agent or human reading "132 dead symbols" in a Terraform repo could try to delete live infrastructure.

This is explicitly not the same situation as a language where call resolution is simply not implemented yet (e.g. bash/ruby/lua carry real dead code a future resolver could find, hence their 0.0/0.0 benchmark thresholds reflect an engineering gap, not a language-capability gap). HCL's absence of call edges is by design — the README support matrix already documents it as parse-only.

Changes

• src/graph/classifiers/roles.ts: added isDeclarativeLanguageNode (checks the node's file extension against .tf/.hcl) and gated it at the top of classifyNodeRole, mirroring the existing carve-out for interface/type declaration members that can never be judged by call-graph reachability either. Declarative-language nodes are now classified leaf unconditionally — reusing the existing role rather than introducing a new enum value, since leaf already carries exactly this "not judged by call-graph reachability" semantic elsewhere in this file (and gets the same low ROLE_WEIGHTS score, 0.2, appropriate for infra-as-code declarations).
• crates/codegraph-core/src/graph/classifiers/roles.rs: mirrored the identical carve-out in classify_node, so the native and WASM engines stay in parity.
• Added test coverage in both engines: tests/graph/classifiers/roles.test.ts (JS, both .tf and .hcl, including an exported node) and a new Rust unit test hcl_resource_with_zero_fan_in_is_leaf_not_dead.

Verification

• lint: pass
• cargo fmt -- --check / cargo clippy --workspace --all-targets -- -D warnings: pass
• npx vitest run tests/graph/ tests/integration/roles.test.ts tests/unit/roles.test.ts: 300/300 pass
• cargo test --package codegraph-core graph::classifiers::roles: 15/15 pass (including the new test)
• codegraph diff-impact --staged: 2 functions changed, 5 callers affected — contained to the role-classification call chain
• Manually reproduced the issue's exact Terraform fixture (KMS key + S3 bucket + SSE config + output, all cross-referenced) against a freshly built native addon (napi build, not the stale prebuilt one) and the WASM engine: all 4 symbols now classify leaf instead of dead-unresolved, confirmed identical across both engines

Also filed

• test(hcl): resolution-benchmark fixture's expected module-reference edges never materialize #2524 — split out the issue's secondary observation (the HCL resolution-benchmark fixture's expected module-reference edges never materialize) as a separate, distinct piece of resolver work not part of this dead-code classification fix

Closes #2385

[greptile-apps]

Greptile Summary

The PR prevents Terraform/HCL declarations from receiving misleading call-graph-based dead-code verdicts while preserving native and TypeScript classifier parity.

• Adds an early leaf classification for .tf and .hcl nodes in both role-classification engines.
• Adds TypeScript coverage for both declarative extensions and Rust coverage for Terraform resources.

Confidence Score: 5/5

The PR appears safe to merge, with the declarative-language carve-out consistently implemented across both engines.

The supported Terraform/HCL extensions, emitted node kinds, and shared file-path inputs align with the new classification logic, and no blocking or independently actionable issue remains.

Important Files Changed

Filename	Overview
src/graph/classifiers/roles.ts	Adds a declarative-extension predicate and classifies Terraform/HCL nodes as leaf before call-graph-based role logic.
crates/codegraph-core/src/graph/classifiers/roles.rs	Mirrors the declarative-language carve-out in the native classifier and adds a focused Rust regression test.
tests/graph/classifiers/roles.test.ts	Verifies that exported and unexported nodes from both .tf and .hcl files are classified as leaf.

_{Reviews (1): Last reviewed commit: "fix(roles): stop emitting dead-* verdict..." | Re-trigger Greptile}

[github-actions]

Codegraph Impact Analysis

2 functions changed → 5 callers affected across 2 files

• isDeclarativeLanguageNode in src/graph/classifiers/roles.ts:93 (4 transitive callers)
• classifyNodeRole in src/graph/classifiers/roles.ts:366 (4 transitive callers)