Objective-C .h files fail to parse unless a .m file preloads the grammar #1628

Summary

An Objective-C header can fail with Failed to get parser for language: objc when a project contains no .m/.mm file.

CodeGraph initially classifies .h files as C and preloads the C and C++ grammars. After the worker pool has been initialized, content-aware detection correctly reclassifies the header as Objective-C, but the worker has no Objective-C grammar loaded.

This was originally observed in OpenCV's opencv2/videoio/cap_ios.h, but the reproducer below has no dependencies or imports.

Environment

• CodeGraph 1.6.0
• Linux 5.15 x86_64

Minimal reproduction

Create an otherwise empty directory containing exactly this file:

repro.h

@interface CGRepro
- (void)run;
@end

Run:

$ codegraph init --yes

Actual result:

Indexing failed — all 1 files had errors

1 parser initialization failures

.codegraph/errors.log:

1 files with errors

repro.h: Failed to get parser for language: objc

codegraph status --json reports fileCount: 1, nodeCount: 0, languages: ["objc"], and state: "failed".

The same failure reproduces with a subsequent codegraph index.

Expected result

repro.h should be parsed as Objective-C and its class/method should be indexed, without requiring a sibling .m or .mm file.

Control experiment

Adding this second file causes both files to index successfully:

grammar_seed.m

void codegraph_objc_grammar_seed(void) {}

With that file present, codegraph index reports:

Indexed 2 files
4 nodes, 2 edges

Removing grammar_seed.m and rebuilding restores the parser initialization failure.

Diagnosis

The failure is deterministic:

path-only detection:       repro.h -> c
preloaded grammars:        c, cpp
content-aware detection:  repro.h -> objc
getParser("objc"):        null

Loading the Objective-C grammar explicitly changes getParser("objc") from null to a valid parser, so the shipped tree-sitter-objc.wasm is present and loadable.

The preload logic currently derives neededLanguages without file contents and adds cpp when c is present, but not objc:

https://github.com/colbymchenry/codegraph/blob/main/src/extraction/index.ts#L1665-L1669

Later, parsing performs content-aware detection and sends the resulting objc language to the already initialized worker.

Possible fixes

• When .h/C is present, preload both cpp and objc; or
• lazily load the final content-detected grammar in the worker.

Either approach should preserve the current content-aware .h detection while ensuring the selected parser is available.