fix(extractors): extract rest/default bindings from dynamic import() destructures

[carlos-alm]

Summary

• extractDynamicImportNames (WASM/TS) only recognized shorthand_property_identifier_pattern and pair_pattern children when collecting names from an object-pattern destructure of a dynamic import() result, so a rest element (...rest) was silently dropped entirely and a shorthand default ({ a = 1 }) produced no name at all.
• The issue assumed the native engine "already handles both cases correctly." That turned out to be only half true — verified empirically with a temporary cargo test before writing the fix (removed afterward): native's object_assignment_pattern (default-value) handling was correct, but its shared extract_rest_identifier helper indexed into a fixed child slot (child(0)) that is actually the ... token, not the bound identifier — so native also silently dropped rest bindings, for both object-pattern and array-pattern dynamic-import destructures.
• Fixed both engines so they now agree and are both correct:
  • TS: added object_assignment_pattern and rest_pattern/rest_element branches to extractDynamicImportNames's object_pattern handling. Extracted a shared extractRestPatternIdentifier helper that scans all children for the actual identifier node (rather than assuming a fixed index) and reused it to fix the array_pattern branch's identical pre-existing bug.
  • Rust: fixed extract_rest_identifier to scan all children for the identifier node instead of assuming child(0), mirroring the already-correct pattern used by extract_array_pattern_bindings elsewhere in the same file. This one shared helper backs both collect_object_pattern_names and collect_array_pattern_names, so the fix covers object- and array-pattern destructures in one change.
• Both TS extraction code paths (walk-based collectDynamicImport and query-based handleDynamicImportCall) call the same shared extractDynamicImportNames function, so both are fixed by this one change (confirmed via codegraph fn-impact).

Closes #1920

Test plan

• npx vitest run tests/parsers/javascript.test.ts — 254 passed (4 new, covering rest/default/mixed bindings in object patterns and rest in array patterns)
• cargo test --lib javascript (crates/codegraph-core) — 187 passed (4 new, mirroring the TS cases)
• cargo test (crates/codegraph-core, full crate) — 603 passed, 0 failed
• Built and codesigned the native addon locally (npx napi build --platform --release + codesign --sign - --force) so the full suite could exercise the real native engine rather than silently skipping it
• npm test — full suite: 254 files, 4023 passed, 30 skipped, 2 todo, 0 failed
• npm run lint — clean on touched files
• codegraph diff-impact --staged -T — confirms the change is scoped to exactly the two functions touched (extractRestPatternIdentifier, extractDynamicImportNames), 12 transitive callers, all within the JS/TS extractor

Filed #2051 for an out-of-scope finding discovered while investigating: extractDestructuredBindings/extract_destructured_bindings (the generic object-destructuring-to-Definition extractor used for plain const { a, ...rest } = x declarations, unrelated to dynamic imports) has the same rest/default gap in both engines.

Stacked on #1914 per the current PR chain — only the extractor/test diff is this issue's change.

[greptile-apps]

Greptile Summary

This PR fixes a silent data-loss bug in dynamic import() destructure extraction for both the TypeScript (WASM) and Rust (native) engines: rest bindings (...rest) were dropped entirely and shorthand default bindings ({ a = 1 }) produced no name at all because both implementations assumed a fixed child index that actually pointed at the ... punctuation token rather than the identifier.

• TypeScript engine: introduces extractRestPatternIdentifier (scans all children for identifier type), wires it into the object_pattern branch of extractDynamicImportNames alongside a new object_assignment_pattern arm for shorthand defaults, and replaces the broken fixed-index fallback in the array_pattern branch.
• Rust engine: replaces child(0) in extract_rest_identifier with an identical child-scanning loop, fixing both collect_object_pattern_names and collect_array_pattern_names through the shared helper.
• Tests: 4 new tests per engine (object rest, shorthand default, mixed, array rest) mirror each other across TS and Rust.

Confidence Score: 5/5

Safe to merge — both engines now agree and the fix is narrow and well-tested.

The change is a targeted two-line root cause fix in each engine (replace fixed-index child(0) access with a child-type scan) plus the new object_assignment_pattern arm in the TS extractor. Logic is symmetric across TS and Rust, the new extractRestPatternIdentifier helper matches the comment-documented intent of its Rust counterpart, and four regression tests per engine cover every affected code path. No existing behavior is altered for the already-correct cases.

No files require special attention.

Important Files Changed

Filename	Overview
crates/codegraph-core/src/extractors/javascript.rs	Fixes extract_rest_identifier to scan children for identifier rather than using child(0) (the ... token); adds 4 regression tests.
src/extractors/javascript.ts	Adds extractRestPatternIdentifier helper and handles object_assignment_pattern / rest_pattern / rest_element in extractDynamicImportNames; fixes the same fixed-index bug in the array_pattern branch.
tests/parsers/javascript.test.ts	Adds 4 new regression tests covering object rest, shorthand default, mixed pattern, and array rest destructuring of dynamic imports.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["dynamic import() call node"] --> B["Walk up AST through wrappers\nawait / parenthesized / as_expression"]
    B --> C{"variable_declarator?"}
    C -- No --> Z["return []"]
    C -- Yes --> D["childForFieldName('name')"]
    D --> E{"nameNode.type"}
    E -- identifier --> F["return [nameNode.text]"]
    E -- object_pattern --> G["iterate children"]
    E -- array_pattern --> H["iterate children"]
    G --> G1{"child.type"}
    G1 -- shorthand_property_identifier_pattern --> G2["push child.text"]
    G1 -- pair_pattern --> G3["extract local/key\npush local, record rename"]
    G1 -- object_assignment_pattern NEW --> G4["childForFieldName('left')\npush left.text"]
    G1 -- rest_pattern/rest_element NEW --> G5["extractRestPatternIdentifier\nscan children for identifier"]
    H --> H1{"child.type"}
    H1 -- identifier --> H2["push child.text"]
    H1 -- rest_pattern/rest_element FIXED --> H3["extractRestPatternIdentifier\n(was: child(0) = ... token)"]
    G5 --> R["return names"]
    G2 --> R
    G3 --> R
    G4 --> R
    H2 --> R
    H3 --> R

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flowchart TD
    A["dynamic import() call node"] --> B["Walk up AST through wrappers\nawait / parenthesized / as_expression"]
    B --> C{"variable_declarator?"}
    C -- No --> Z["return []"]
    C -- Yes --> D["childForFieldName('name')"]
    D --> E{"nameNode.type"}
    E -- identifier --> F["return [nameNode.text]"]
    E -- object_pattern --> G["iterate children"]
    E -- array_pattern --> H["iterate children"]
    G --> G1{"child.type"}
    G1 -- shorthand_property_identifier_pattern --> G2["push child.text"]
    G1 -- pair_pattern --> G3["extract local/key\npush local, record rename"]
    G1 -- object_assignment_pattern NEW --> G4["childForFieldName('left')\npush left.text"]
    G1 -- rest_pattern/rest_element NEW --> G5["extractRestPatternIdentifier\nscan children for identifier"]
    H --> H1{"child.type"}
    H1 -- identifier --> H2["push child.text"]
    H1 -- rest_pattern/rest_element FIXED --> H3["extractRestPatternIdentifier\n(was: child(0) = ... token)"]
    G5 --> R["return names"]
    G2 --> R
    G3 --> R
    G4 --> R
    H2 --> R
    H3 --> R

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[github-actions]

Codegraph Impact Analysis

2 functions changed → 12 callers affected across 1 files

• extractRestPatternIdentifier in src/extractors/javascript.ts:4696 (5 transitive callers)
• extractDynamicImportNames in src/extractors/javascript.ts:4725 (16 transitive callers)