refactor: register hardcoded execFileSync/execSync maxBuffer values in DEFAULTS

[carlos-alm]

Summary

• Registered 3 previously-hardcoded maxBuffer values (values unchanged) as named DEFAULTS entries: DEFAULTS.build.execMaxBufferBytes (100MB, native-orchestrator.ts), DEFAULTS.check.execMaxBufferBytes (10MB, check.ts + diff-impact.ts), DEFAULTS.coChange.execMaxBufferBytes (50MB, cochange.ts) — matching the existing precedent set by resolveSecrets's config.ts fix.
• Threaded through wherever the call site already resolves a config object; cochange.ts reads DEFAULTS.coChange.* directly to match that file's existing convention (no resolved-config parameter flows through it today).

Closes #1739

Test plan

• npm test — full suite green (3444 passed, 0 failed)
• npm run lint / npx tsc --noEmit — clean

Stacked on #1840 (base branch fix/issue-1738-structure-metrics-incremental-stale) — only the config/analysis/features/docs diff is this issue's change.

[greptile-apps]

Greptile Summary

This PR registers three previously-hardcoded execFileSync maxBuffer values as named DEFAULTS entries (build.execMaxBufferBytes, check.execMaxBufferBytes, coChange.execMaxBufferBytes), adds them to CodegraphConfig, and threads each value from the config through to its call site — no numeric values change.

• build.execMaxBufferBytes (100 MB): wired into queryGitIgnoredFiles via ctx.config.build.execMaxBufferBytes in the native-orchestrator pipeline stage.
• check.execMaxBufferBytes (10 MB): wired into both getGitDiff (check.ts) and runGitDiff (diff-impact.ts) via the resolved config, shared by both call sites.
• coChange.execMaxBufferBytes (50 MB): fully threaded from ctx.config.coChange in the CLI command → analyzeCoChanges → resolveCoChangeAnalysisOptions → runCoChangeScanAndPersist → scanGitHistory (with ?? DEFAULTS.coChange.execMaxBufferBytes fallback), addressing the previously-noted issue where the value was read directly from DEFAULTS.

Confidence Score: 5/5

Safe to merge — no behaviour changes, values unchanged, and the previously-flagged user-config bypass in cochange.ts is fully resolved.

The change is a pure extraction of hardcoded literals into named config entries. Every call site already held a resolved config object (or falls back to loadConfig()), so the new fields are available everywhere they are read. The coChange threading path is complete from CLI → analyzeCoChanges → resolveCoChangeAnalysisOptions → runCoChangeScanAndPersist → scanGitHistory with a correct nullish-coalescing fallback. Documentation byte values match the code exactly.

No files require special attention.

Important Files Changed

Filename	Overview
src/infrastructure/config.ts	Adds execMaxBufferBytes to DEFAULTS.build (100 MB), DEFAULTS.check (10 MB), and DEFAULTS.coChange (50 MB) with JSDoc comments; values match previous hardcoded literals exactly.
src/types.ts	Adds execMaxBufferBytes field to the build, check, and coChange sections of CodegraphConfig; documentation comments reference the correct byte values and call sites.
src/features/cochange.ts	Threads execMaxBufferBytes through scanGitHistory opts → resolveCoChangeAnalysisOptions → CoChangeAnalysisOptions → runCoChangeScanAndPersist; fallback to DEFAULTS is correctly nullish-coalesced.
src/cli/commands/co-change.ts	Adds coChangeConfig?.execMaxBufferBytes to the analyzeCoChanges call, completing the user-config → CLI → feature layer threading.
src/domain/analysis/diff-impact.ts	runGitDiff now accepts maxBuffer explicitly; diffImpactData passes config.check.execMaxBufferBytes (config resolved from opts or loadConfig()).
src/features/check.ts	getGitDiff now accepts maxBuffer explicitly; checkData passes config.check.execMaxBufferBytes, keeping the same 10 MB default behavior.
src/domain/graph/builder/stages/native-orchestrator.ts	queryGitIgnoredFiles now accepts maxBuffer; detectDroppedLanguageGap passes ctx.config.build.execMaxBufferBytes, preserving the 100 MB default.
docs/guides/configuration.md	Documents all three new execMaxBufferBytes fields with correct byte-value defaults (104857600, 10485760, 52428800) and accurate descriptions of the spawned subprocess.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    subgraph config ["Config Layer"]
        D["DEFAULTS / CodegraphConfig"]
        D --> B["build.execMaxBufferBytes\n100 MB"]
        D --> C["check.execMaxBufferBytes\n10 MB"]
        D --> CO["coChange.execMaxBufferBytes\n50 MB"]
    end

    subgraph build_path ["Build Path"]
        B --> NO["native-orchestrator.ts\ndetectDroppedLanguageGap()"]
        NO --> QGI["queryGitIgnoredFiles(rootDir, paths, maxBuffer)\nexecFileSync git check-ignore"]
    end

    subgraph check_path ["Check / Diff-Impact Path"]
        C --> CHK["check.ts\ncheckData()"]
        CHK --> GGD["getGitDiff(repoRoot, opts, maxBuffer)\nexecFileSync git diff"]
        C --> DI["diff-impact.ts\ndiffImpactData()"]
        DI --> RGD["runGitDiff(repoRoot, opts, maxBuffer)\nexecFileSync git diff"]
    end

    subgraph cochange_path ["Co-Change Path"]
        CO --> CLI["co-change.ts CLI\ncoChangeConfig?.execMaxBufferBytes"]
        CLI --> AC["analyzeCoChanges(opts)"]
        AC --> RES["resolveCoChangeAnalysisOptions()"]
        RES --> RCP["runCoChangeScanAndPersist()"]
        RCP --> SGH["scanGitHistory(repoRoot, opts)\nexecFileSync git log"]
        SGH --> FB["opts.execMaxBufferBytes ??\nDEFAULTS.coChange.execMaxBufferBytes"]
    end

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flowchart TD
    subgraph config ["Config Layer"]
        D["DEFAULTS / CodegraphConfig"]
        D --> B["build.execMaxBufferBytes\n100 MB"]
        D --> C["check.execMaxBufferBytes\n10 MB"]
        D --> CO["coChange.execMaxBufferBytes\n50 MB"]
    end

    subgraph build_path ["Build Path"]
        B --> NO["native-orchestrator.ts\ndetectDroppedLanguageGap()"]
        NO --> QGI["queryGitIgnoredFiles(rootDir, paths, maxBuffer)\nexecFileSync git check-ignore"]
    end

    subgraph check_path ["Check / Diff-Impact Path"]
        C --> CHK["check.ts\ncheckData()"]
        CHK --> GGD["getGitDiff(repoRoot, opts, maxBuffer)\nexecFileSync git diff"]
        C --> DI["diff-impact.ts\ndiffImpactData()"]
        DI --> RGD["runGitDiff(repoRoot, opts, maxBuffer)\nexecFileSync git diff"]
    end

    subgraph cochange_path ["Co-Change Path"]
        CO --> CLI["co-change.ts CLI\ncoChangeConfig?.execMaxBufferBytes"]
        CLI --> AC["analyzeCoChanges(opts)"]
        AC --> RES["resolveCoChangeAnalysisOptions()"]
        RES --> RCP["runCoChangeScanAndPersist()"]
        RCP --> SGH["scanGitHistory(repoRoot, opts)\nexecFileSync git log"]
        SGH --> FB["opts.execMaxBufferBytes ??\nDEFAULTS.coChange.execMaxBufferBytes"]
    end

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_{Reviews (3): Last reviewed commit: "fix: thread coChange.execMaxBufferBytes ..." | Re-trigger Greptile}

[github-actions]

Codegraph Impact Analysis

16 functions changed → 16 callers affected across 12 files

• command.execute in src/cli/commands/co-change.ts:22 (0 transitive callers)
• execute in src/cli/commands/co-change.ts:22 (0 transitive callers)
• runGitDiff in src/domain/analysis/diff-impact.ts:41 (4 transitive callers)
• diffImpactData in src/domain/analysis/diff-impact.ts:259 (3 transitive callers)
• queryGitIgnoredFiles in src/domain/graph/builder/stages/native-orchestrator.ts:1460 (4 transitive callers)
• detectDroppedLanguageGap in src/domain/graph/builder/stages/native-orchestrator.ts:1527 (4 transitive callers)
• getGitDiff in src/features/check.ts:455 (4 transitive callers)
• checkData in src/features/check.ts:527 (3 transitive callers)
• scanGitHistory in src/features/cochange.ts:72 (3 transitive callers)
• CoChangeAnalysisOptions.execMaxBufferBytes in src/features/cochange.ts:275 (0 transitive callers)
• resolveCoChangeAnalysisOptions in src/features/cochange.ts:279 (2 transitive callers)
• runCoChangeScanAndPersist in src/features/cochange.ts:294 (2 transitive callers)
• analyzeCoChanges in src/features/cochange.ts:319 (1 transitive callers)
• CodegraphConfig.build in src/types.ts:1327 (0 transitive callers)
• CodegraphConfig.check in src/types.ts:1452 (0 transitive callers)
• CodegraphConfig.coChange in src/types.ts:1466 (0 transitive callers)

[carlos-alm]

@greptileai