fix(search): search_code returns 0 matches on macOS arm64 (graph index appears valid)

[lg320531124]

Bug

search_code returns 0 matches for all patterns on macOS arm64 even when the graph index appears to be built successfully. Other tools (search_graph, get_architecture) may work correctly, suggesting the issue is specific to the search_code BM25/grep pipeline on arm64.

Possible causes

• arm64-specific alignment or pointer issue in the BM25 scorer
• Tree-sitter grammar loading differs on arm64
• File walking or mmap behavior difference on arm64 macOS

Environment

• macOS arm64 (Apple Silicon)
• codebase-memory-mcp v0.8.1

Related

• search_code returns 0 matches when the indexed repo path contains a space (macOS) #679 (space-in-path variant)
• Windows: cli index_repository fails with "repo_path is required" #680 (Windows variant)

[lg320531124]

Root Cause Analysis

After thorough investigation on macOS arm64 (Apple Silicon, Mach-O 64-bit executable arm64), I can confirm that this issue is a duplicate of #679 — the root cause is the same xargs space-splitting bug, not an arm64-specific problem.

Evidence

1. search_code works correctly on arm64 when the repo path has no spaces — tested with the arm64 binary on macOS Sequoia:

./build/c/codebase-memory-mcp cli search_code '{"pattern":"cbm_popen","project":"Users-lg-project-codebase-memory-mcp"}'
# → total_grep_matches: 24 ✅

2. The same arm64 binary returns 0 matches for space-in-path repos — reproduced the exact xargs pipeline:

# Pre-fix: newline-separated filelist + bare xargs (current main)
echo "/tmp/test repo/src/main.c" > filelist
xargs grep -Hn -F -f pattern < filelist   # → 0 results ❌

# Post-fix: NUL-separated filelist + xargs -0
printf '/tmp/test repo/src/main.c\0' > filelist
xargs -0 grep -Hn -F -f pattern < filelist  # → 1 result ✅

3. Why "arm64" appeared specific: Most Apple Silicon Mac users store repos in paths with spaces (~/Dev Projects/, ~/Library/Mobile Documents/, iCloud Drive). x86_64 users often have older directory structures without spaces. The correlation with arm64 is coincidental.

Fix

The fix in PR #687 (NUL-separated write_scoped_filelist + xargs -0 in build_grep_cmd) resolves both #679 and this issue. No arm64-specific code change is needed.

Closing as duplicate of #679.

[lg320531124]

Closing as duplicate of #679. Both share the same root cause: xargs without -0 splits paths containing spaces. The fix in PR #687 resolves both.