fix(exports): credit plain imports of TypeScript interfaces/type aliases

[carlos-alm]

Summary

codegraph exports/dead-export analysis (the same query the pre-commit dead-export gate uses) only credited a symbol-level imports-type edge when the importing statement was syntactically marked type-only — a whole-statement import type { X } (#1724) or the inline import { type X } modifier (#1813).

TypeScript also allows importing an interface or type alias through a plain import { X } from 'y' with no type keyword at all — an extremely common pattern in codebases that don't enforce import/consistent-type-imports. Since interfaces and type aliases are erased before runtime, they can never receive a calls edge either, so a plain import was the only possible consumption signal, and it was being ignored — permanently misclassifying every such interface/type alias as a dead export, even when it's genuinely used everywhere.

Root cause & fix

imports-type crediting was gated on the importing statement's syntax rather than the resolved target's actual kind. The fix classifies crediting by whether the resolved target is a TypeScript interface/type-alias declaration (isTypeErasedImportTarget in shared/kinds.ts, mirrored as is_type_erased_import_target in Rust's shared/constants.rs) — regardless of whether the import statement used the type keyword.

• A plain import of a value symbol (function, class, const) is unaffected — its consumption credit still requires a real calls edge, so genuinely-unused value imports still correctly show 0 consumers.
• Scoped specifically to .ts/.tsx files, since other languages reuse the 'interface'/'type' node kinds for constructs that are runtime-observable (e.g. a Go type alias, a Java interface dispatched through at runtime) — crediting those on mere import would mask genuinely dead code instead of fixing a false positive.

Dual-engine parity

Mirrored in all four import-edge-building code paths per this repo's dual-engine architecture:

• src/domain/graph/builder/stages/build-edges.ts (JS/WASM full build)
• src/domain/graph/builder/incremental.ts (JS/WASM incremental / watch)
• crates/codegraph-core/src/domain/graph/builder/stages/build_edges.rs (native FFI-hybrid path, used e.g. on --force full rebuilds)
• crates/codegraph-core/src/domain/graph/builder/stages/import_edges.rs (native orchestrator's pure-Rust path — the primary path for --engine native)

Test plan

• New fixture tests/fixtures/issue-1833-plain-type-import/ + tests/integration/issue-1833-plain-type-import.test.ts — a plain import { Config, Mode } from './types.js' (no type keyword) used only in type position; verifies both Config (interface) and Mode (type alias) get a symbol-level imports-type edge and are reported as consumed via exportsData/codegraph exports, on both wasm and native engines. Also verifies a genuinely-unimported export (helper) still correctly reports 0 consumers.
• New Rust unit tests in both build_edges.rs and import_edges.rs covering: plain import of a TS interface (credited), plain import of a TS value symbol (not credited), and plain import of a non-TypeScript 'interface'-kind node e.g. Go (not credited — heuristic correctly scoped to TS).
• Reproduced the original repro from exports/dead-export analysis never counts consumers of TypeScript interfaces/type aliases #1833 (codegraph exports src/types.ts -T on this repo's own LanguageRegistryEntry) — confirmed the manual fix path, then added a minimal synthetic reproduction (import { Foo, Bar } from './types' with no type keyword, used only as parameter/return types) that failed identically on both engines before the fix and passes after.
• Full suite: npm test — 229 test files, 3773 passed (30 pre-existing skipped, 2 pre-existing todo).
• cargo test --lib in crates/codegraph-core — 539 passed, including 18 tests in build_edges.rs's import_edge_tests module and 11 in import_edges.rs's tests module (new tests added for this fix).
• npm run lint — clean (one intentional useImportType warning on the fixture itself, which deliberately uses the plain-import syntax under test; non-blocking).
• npm run build and cargo check --lib / cargo clippy --lib — clean, no new warnings introduced.
• codegraph diff-impact --staged -T reviewed — blast radius limited to the modified import-edge-building functions and their direct/transitive callers, as expected.

Fixes #1833

[greptile-apps]

Greptile Summary

This PR credits plain imports of erased TypeScript exports in dead-export analysis. The main changes are:

• Adds shared helpers for interface/type-alias import classification.
• Updates JS full-build and incremental import-edge creation.
• Updates both Rust import-edge builders for native parity.
• Adds fixture and integration coverage for plain .ts type imports.

Confidence Score: 4/5

The changed import-credit flow needs an extension-parity fix before merging.

• Plain imports from .mts and .cts type exports can still be reported as dead.
• The issue affects both the JS helper and the native Rust helper.
• The core .ts and .tsx paths appear consistent across the changed builders.

src/shared/kinds.ts and crates/codegraph-core/src/shared/constants.rs

Important Files Changed

Filename	Overview
src/domain/graph/builder/stages/build-edges.ts	Full-build JS import-edge emission now credits plain imports when the resolved target kind is erased.
src/domain/graph/builder/incremental.ts	Incremental JS import-edge emission mirrors the full-build behavior using DB candidate kind data.
src/shared/kinds.ts	Adds erased-target classification, but its extension gate misses TypeScript module files.
crates/codegraph-core/src/domain/graph/builder/stages/build_edges.rs	Native FFI-hybrid import-edge building now carries symbol kind and credits erased TypeScript targets.
crates/codegraph-core/src/domain/graph/builder/stages/import_edges.rs	Pure Rust import-edge building now loads symbol kind and widens lookup collection for possible erased targets.
crates/codegraph-core/src/shared/constants.rs	Adds Rust-side erased-target classification, but its TypeScript extension list is incomplete.
tests/integration/issue-1833-plain-type-import.test.ts	Adds regression coverage for plain imports of .ts interface and type-alias exports on both engines.

_{Reviews (1): Last reviewed commit: "fix(exports): credit plain imports of Ty..." | Re-trigger Greptile}

[greptile-apps]

TypeScript Modules Stay Uncredited

When a plain import resolves to an interface or type alias in a .mts or .cts file, this check returns false because path.extname(file) is compared against a set containing only .ts and .tsx. Those TypeScript module files can still export erased declarations, so the new imports-type credit is skipped and codegraph exports can still report the used type export as dead.

[greptile-apps]

Native TypeScript Modules Stay Uncredited

The native builders use this list to decide whether a plain import can credit an erased TypeScript target, but it excludes .mts and .cts. A plain import of an interface or type from those module files therefore fails is_type_erased_import_target, so the native codegraph exports path can still mark the used export as dead.

Suggested change

	pub const TYPESCRIPT_EXTENSIONS: [&str; 2] = [".ts", ".tsx"];
	pub const TYPESCRIPT_EXTENSIONS: [&str; 4] = [".ts", ".tsx", ".mts", ".cts"];

[github-actions]

Codegraph Impact Analysis

14 functions changed → 25 callers affected across 8 files

• emitNamedSymbolEdges in src/domain/graph/builder/incremental.ts:423 (4 transitive callers)
• emitEdgesForImport in src/domain/graph/builder/incremental.ts:466 (5 transitive callers)
• emitNamedSymbolEdges in src/domain/graph/builder/stages/build-edges.ts:230 (3 transitive callers)
• emitEdgesForImport in src/domain/graph/builder/stages/build-edges.ts:267 (3 transitive callers)
• collectSymbolNodes in src/domain/graph/builder/stages/build-edges.ts:490 (3 transitive callers)
• parseFileAuto in src/domain/parser.ts:1111 (5 transitive callers)
• backfillTypeMapBatch in src/domain/parser.ts:1141 (7 transitive callers)
• ingestNativeResults in src/domain/parser.ts:1311 (7 transitive callers)
• parseFileIncremental in src/domain/parser.ts:1427 (6 transitive callers)
• isTypeErasedImportTarget in src/shared/kinds.ts:109 (6 transitive callers)
• NativeAddon.buildImportEdges in src/types.ts:2342 (0 transitive callers)
• useConfig in tests/fixtures/issue-1833-plain-type-import/consumer.ts:8 (0 transitive callers)
• Config.name in tests/fixtures/issue-1833-plain-type-import/types.ts:2 (0 transitive callers)
• helper in tests/fixtures/issue-1833-plain-type-import/types.ts:7 (0 transitive callers)