fix: backfill edges.technique for incrementally-inserted calls edges

[carlos-alm]

Summary

Two independent gaps, both in the JS-side technique backfill (native Rust never writes this column, by design, for either full or incremental builds):

1. incremental.ts's emitIncrementalCallEdges (used by codegraph watch) inserted calls edges without ever setting technique. Added backfillIncrementalEdgeTechniques, scoped to the rebuilt file + its reverse deps, mirroring the full-build backfill's pattern. Applies regardless of engine — technique='ts-native' turned out not to be a native-only marker, but the label both engines' full-build paths apply identically to directly-resolved edges (vs. 'points-to'/'cha'/'super-dispatch').
2. native-orchestrator.ts's incremental backfill scoped its UPDATE to only the Rust-reported changedFiles, missing one-hop reverse dependents whose edges get reconnected by Rust's own cascade (reconnect_reverse_dep_edges) — those get new rows with technique never set. Added findOneHopReverseDepFiles to expand the scope.

Closes #1744

Test plan

• npm test — full suite green (3489 passed, 0 failed)
• npm run lint / npm run typecheck — clean
• New tests compare exact technique/confidence equality between incremental and full rebuilds of identical post-edit state, for both the native-orchestrator path and the watch/rebuildFile path (both engines) — confirmed failing with the fix reverted, passing restored

Filed #1852 for a more serious pre-existing bug found during investigation: incremental.ts's call resolution implements only a subset of the full-build cascade, so codegraph watch silently drops (not just mislabels) CHA-dispatched, points-to-resolved, and dynamic-sink call edges on single-file rebuilds — empirically confirmed (3 edges full build → 1 edge after a trivial watch-mode edit). Out of scope for this fix.

Stacked on #1851 (base branch fix/issue-1743-incremental-stale-cyclomatic) — only the incremental/native-orchestrator/constants/test diff is this issue's change.

[greptile-apps]

Greptile Summary

Fixes two independent gaps that left technique NULL on calls edges after incremental rebuilds: the watch-mode rebuildFile path never ran any backfill, and the native-orchestrator's incremental backfill was scoped only to directly-changed files, missing one-hop reverse dependents whose edges are silently reconnected by Rust's own cascade.

• incremental.ts: adds backfillIncrementalEdgeTechniques, called unconditionally at the end of rebuildFile, which sets technique='ts-native' for all NULL-technique calls edges in the rebuilt file and its reverse deps, then lifts any that fall below TS_NATIVE_CONFIDENCE_FLOOR — mirroring the full-build paths for both engines.
• native-orchestrator.ts: adds findOneHopReverseDepFiles (scoped to e.kind='calls') to expand backfillEdgeTechniquesAfterNativeOrchestrator's incremental scope to include reverse-dependent callers whose reconnected edges carry a fresh NULL technique.
• New integration tests in issue-1744-incremental-edge-technique.test.ts assert exact technique/confidence equality between an incremental rebuild and a reference full rebuild for both affected paths.

Confidence Score: 5/5

Safe to merge — both fix paths are logically correct and covered by new integration tests that assert exact parity with full rebuilds.

The changes are narrowly scoped backfills with correct UPDATE conditions (technique IS NULL, kind = 'calls'), so pre-existing technique values on unchanged edges are never overwritten. The findOneHopReverseDepFiles query in native-orchestrator.ts is already scoped to calls edges. The one minor observation is that backfillIncrementalEdgeTechniques in incremental.ts receives the broader all-edge-kinds reverseDeps list rather than a calls-scoped one, but the UPDATE conditions guarantee no incorrect writes — it is a scan-width concern only. Tests cover both the watch-mode and native-orchestrator incremental paths across wasm and native engines.

No files require special attention.

Important Files Changed

Filename	Overview
src/domain/graph/builder/incremental.ts	Adds backfillIncrementalEdgeTechniques called at the end of rebuildFile, correctly setting technique='ts-native' and lifting the confidence floor for all newly inserted calls edges. The backfill scope is [relPath, ...reverseDeps] where reverseDeps is the broader all-edge-kinds list used by the cascade; this is a minor efficiency concern but not a correctness issue.
src/domain/graph/builder/stages/native-orchestrator.ts	Adds findOneHopReverseDepFiles (correctly scoped to e.kind = 'calls') and expands backfillEdgeTechniquesAfterNativeOrchestrator's incremental scope to include one-hop reverse dependents whose edges are reconnected by Rust's cascade without a technique value.
src/shared/constants.ts	Doc comment update only — adds incremental.ts to the list of callers of TS_NATIVE_CONFIDENCE_FLOOR.
tests/integration/issue-1744-incremental-edge-technique.test.ts	New integration test covering both fix paths: Suite 1 exercises the native orchestrator's incremental backfill, Suite 2 exercises rebuildFile directly for both wasm and native engines. Both suites compare exact technique/confidence equality against a fresh full rebuild of the same post-edit state.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant W as codegraph watch
    participant R as rebuildFile
    participant B as buildCallEdges
    participant DB as SQLite DB
    participant BF as backfillIncrementalEdgeTechniques

    W->>R: rebuildFile(db, rootDir, filePath)
    R->>DB: findReverseDeps(relPath)
    DB-->>R: reverseDeps [callerA, callerB, ...]
    R->>DB: purgeFileData(relPath)
    R->>B: rebuildEdgesForTargetFile
    B->>DB: "insertEdge(...) [technique=NULL]"
    R->>B: runReverseDepCascade(reverseDeps)
    B->>DB: "insertEdge(...) [technique=NULL]"
    Note over R,BF: NEW: backfill runs after all edges inserted
    R->>BF: backfillIncrementalEdgeTechniques(db, [relPath, ...reverseDeps])
    BF->>DB: "UPDATE edges SET technique='ts-native' WHERE kind='calls' AND technique IS NULL"
    BF->>DB: "UPDATE edges SET confidence=floor WHERE technique='ts-native' AND confidence < floor"

    Note over W,DB: native-orchestrator incremental path
    participant NO as native-orchestrator
    participant FOH as findOneHopReverseDepFiles
    NO->>DB: "Rust cascade reconnects reverse-dep edges [technique=NULL]"
    NO->>FOH: findOneHopReverseDepFiles(changedFiles) [NEW]
    FOH->>DB: SELECT files with calls edges targeting changedFiles
    DB-->>FOH: [callerA, callerB, ...]
    FOH-->>NO: "scopeFiles = changedFiles union reverseDepFiles"
    NO->>DB: "UPDATE technique='ts-native' for scopeFiles [was: changedFiles only]"

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sequenceDiagram
    participant W as codegraph watch
    participant R as rebuildFile
    participant B as buildCallEdges
    participant DB as SQLite DB
    participant BF as backfillIncrementalEdgeTechniques

    W->>R: rebuildFile(db, rootDir, filePath)
    R->>DB: findReverseDeps(relPath)
    DB-->>R: reverseDeps [callerA, callerB, ...]
    R->>DB: purgeFileData(relPath)
    R->>B: rebuildEdgesForTargetFile
    B->>DB: "insertEdge(...) [technique=NULL]"
    R->>B: runReverseDepCascade(reverseDeps)
    B->>DB: "insertEdge(...) [technique=NULL]"
    Note over R,BF: NEW: backfill runs after all edges inserted
    R->>BF: backfillIncrementalEdgeTechniques(db, [relPath, ...reverseDeps])
    BF->>DB: "UPDATE edges SET technique='ts-native' WHERE kind='calls' AND technique IS NULL"
    BF->>DB: "UPDATE edges SET confidence=floor WHERE technique='ts-native' AND confidence < floor"

    Note over W,DB: native-orchestrator incremental path
    participant NO as native-orchestrator
    participant FOH as findOneHopReverseDepFiles
    NO->>DB: "Rust cascade reconnects reverse-dep edges [technique=NULL]"
    NO->>FOH: findOneHopReverseDepFiles(changedFiles) [NEW]
    FOH->>DB: SELECT files with calls edges targeting changedFiles
    DB-->>FOH: [callerA, callerB, ...]
    FOH-->>NO: "scopeFiles = changedFiles union reverseDepFiles"
    NO->>DB: "UPDATE technique='ts-native' for scopeFiles [was: changedFiles only]"

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_{Reviews (4): Last reviewed commit: "fix: resolve merge conflicts with main (..." | Re-trigger Greptile}

[github-actions]

Codegraph Impact Analysis

4 functions changed → 9 callers affected across 4 files

• backfillIncrementalEdgeTechniques in src/domain/graph/builder/incremental.ts:821 (3 transitive callers)
• rebuildFile in src/domain/graph/builder/incremental.ts:1002 (4 transitive callers)
• findOneHopReverseDepFiles in src/domain/graph/builder/stages/native-orchestrator.ts:1855 (3 transitive callers)
• backfillEdgeTechniquesAfterNativeOrchestrator in src/domain/graph/builder/stages/native-orchestrator.ts:1886 (3 transitive callers)

[carlos-alm]

@greptileai