fix(utils): normalize path separators in resolve_chunk (semble #244)

[amondnet]

Summary

Port of upstream semble #244 (b491200).

find_related (MCP tool and csp find-related) resolves the target chunk via resolve_chunk, which compared the incoming file_path against each chunk's stored path verbatim. Chunk paths are stored with the platform-native separator, so on Windows a path passed with the other separator (e.g. copied from docs, or typed with /) failed to resolve.

• resolve_chunk now treats \ and / as equal on both sides via a zero-allocation byte comparison (paths_eq_normalized), equivalent to upstream's replace("\\", "/") on both sides.
• The strict-inner-match / end-line-fallback behavior is unchanged.
• Two unit tests: backslash input resolves a forward-slash chunk, and forward-slash input resolves a backslash chunk (including the boundary fallback and a non-match).
• .please/docs/references/semble.md §4.18 notes the separator handling.

Related issue

Closes #88

Checklist

• PR title follows Conventional Commits
• Tests added or updated, and the suite passes (cargo test --workspace: 311 lib + 22 CLI passed)
• Lint/format pass (cargo fmt --all && cargo clippy --all-targets --all-features -- -D warnings)
• Documentation updated if behavior changed
• No breaking change, or a BREAKING CHANGE: note is included

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Summary by cubic

Fixes resolve_chunk to treat \ and / as equal when comparing file paths, so paths passed with the wrong separator (e.g., on Windows) no longer fail to resolve. This port of upstream semble #244 adds tests and updates the docs.

^{Written for commit 2729590. Summary will update on new commits.}

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 7 complexity · 0 duplication

Metric	Results
Complexity	7
Duplication	0

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[gemini-code-assist]

Code Review

This pull request updates the resolve_chunk utility in crates/csp/src/utils.rs to treat backslash and forward slash path separators as equal when matching chunk file paths, resolving upstream issue #244. It introduces a non-allocating helper function paths_eq_normalized to perform this comparison and adds corresponding unit tests to verify the behavior. The documentation in semble.md has also been updated to reflect this change. There are no review comments to assess, and the implementation looks correct and well-tested, so I have no additional feedback to provide.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codspeed-hq]

Merging this PR will not alter performance

✅ 5 untouched benchmarks

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_{Comparing amondnet/parity-normalize-path-separators-in-resolve_chun (2729590) with main (b2de30d)}

[cubic-dev-ai]

No issues found across 2 files

Architecture diagram

sequenceDiagram
    participant Caller as Caller (MCP tool / csp CLI)
    participant Resolver as resolve_chunk()
    participant Norm as paths_eq_normalized()
    participant Store as Chunk Store

    Note over Caller,Store: Chunk Resolution Flow (Cross-Platform)

    Caller->>Resolver: resolve_chunk(chunks, file_path, line)
    Note over Resolver: file_path may use / or \

    loop each chunk
        Resolver->>Norm: paths_eq_normalized(chunk.file_path, file_path)
        Note over Norm: Zero-alloc comparison, treats / and \ as equal
        Norm-->>Resolver: boolean (separator-normalized equality)
        
        alt paths match AND within line range
            alt line < chunk.end_line (strict inner match)
                Resolver-->>Caller: Some(chunk) (immediate return)
            else line == chunk.end_line (boundary fallback)
                Resolver->>Resolver: Save as fallback, continue scanning
            end
        else
            Resolver->>Resolver: Continue to next chunk
        end
    end

    alt Fallback was set
        Resolver-->>Caller: Some(fallback_chunk)
    else No match found
        Resolver-->>Caller: None
    end

    Note over Resolver: Example: chunk stored "src/lib/a.ts"<br/>input "src\lib\a.ts" resolves successfully

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_{Re-trigger cubic}

[greptile-apps]

Greptile Summary

This PR updates chunk resolution to compare forward and backward slashes as equivalent, adds bidirectional separator tests, and documents the behavior. The byte comparison correctly implements the intended normalization, but normalized matching can conflate distinct POSIX filenames containing literal backslashes.

Confidence Score: 4/5

The PR should not merge until exact path identity is preserved when separator-normalized paths are ambiguous.

resolve_chunk now considers distinct POSIX paths equal and returns the first matching chunk, which can seed related-code discovery from the wrong file.

Files Needing Attention: crates/csp/src/utils.rs

Important Files Changed

Filename	Overview
crates/csp/src/utils.rs	Adds allocation-free separator-normalized path comparison and tests, but normalized matching can select the wrong chunk when distinct POSIX paths alias.
.please/docs/references/semble.md	Documents the newly supported slash/backslash equivalence in resolve_chunk.

Prompt To Fix All With AI

### Issue 1
crates/csp/src/utils.rs:139
**Normalized paths can collide**

On Unix, backslash is a valid filename character, so distinct indexed files such as `src/lib/a.ts` and a file literally named `src\lib\a.ts` can coexist. The normalized comparison matches both paths, even when the caller supplies an exact path, and `resolve_chunk` returns whichever matching chunk appears first. This can cause `find_related` to use the wrong file as its seed. Prefer an exact path match before falling back to separator-normalized matching.

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For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "fix(utils): normalize path separators in..." | Re-trigger Greptile}