Feature Request: Reuse `.ck` Index from Parent Directories

[stoerr]

Problem

When running ck inside a subdirectory of an already indexed project, a new .ck directory is created in that subdirectory. This leads to redundant indexes, increased disk usage, and unnecessary re-indexing work.

Proposed Behavior

When executed in a subdirectory, ck should:

1. Traverse upward from the current working directory to locate an existing .ck directory.
2. If found, reuse that index instead of creating a new one.
3. Scope search results to files within the current subdirectory only.

Example

Given:

project/
.ck/
src/
module/

Running:

cd project/src/module
ck “query”

Expected behavior:

• Use project/.ck as the index
• Return only results under project/src/module

Optional Optimization

For performance, ck could optionally:

• Prioritize scanning and updating only files within the current subdirectory
• Defer or avoid reprocessing unrelated parts of the repository

Benefits

• Avoids duplicate .ck directories
• Reduces disk usage and indexing time
• Improves usability in nested workflows
• Aligns with common tooling patterns (e.g., git, npm, etc.)

Notes / Open Questions

• Should there be a flag to disable parent lookup (e.g., --no-parent-index)?

Thanks so much for building such a wonderful tool!

[runonthespot]

Update: the search-side of this is now fixed as of 0.7.6, shipped today.

Specifically what works now:

• Running ck "query" /repo/src/module walks up to find /repo/.ck (this already worked — find_nearest_index_root)
• Results are correctly scoped to files inside /repo/src/module (this is what was broken — see fix(ck-engine): apply path scope before top_k in semantic search #111 / fix(mcp): sandbox tool handlers to allowed filesystem roots #112 for the fix)

Before 0.7.6, the scope filter ran after the global top_k, so a narrow query could return zero results when the top global results lived outside the requested subdir. Fixed by applying the path filter at sidecar-collection time. cargo install ck-search to update.

Still open: ck --index /repo/src/module still creates /repo/src/module/.ck rather than reusing the parent's. That's the next part of your request, leaving this issue open for it. Likely also wants a --no-parent-index flag per your suggestion. Tracking.