refactor(lane): remove dead lane-classification code

[joryirving]

Summary

• Delete buildLaneClassificationPrompt and serializeLaneData from src/lib/issue-lane.ts — both were referenced only by their own tests, never in production. The prompt builder also duplicated src/lib/groomer/llm.ts (drift risk). Remove them + their tests + the now-unused lane-config imports.

Scope notes

• classifyLaneFromSignals (and its "normal" fallback) is live (used by issue-lane, issue-reconciliation) and covered by tests — left untouched.
• The /api/issues/[issueId]/lane route keeps its heuristic classifier path (parseLaneClassification / validateLaneRecord / classifyByHeuristics) — the lightweight manual-override classification, intentionally distinct from the groomer's LLM path.

Verification

• tsc → 0; eslint → clean; vitest issue-lane + lane-config + issue-reconciliation + /lane route → 193 passing.

Closes #507 · part of #498

[its-saffron]

AI Automated Review

Full PR review.

Analysis engine: MiniMax-M2.7@https://litellm.jory.dev/v1 (anthropic) — escalated (fast_low_confidence)

Recommendation: Approve

This PR removes dead code from src/lib/issue-lane.ts as specified in issue PR 507. The changes are safe, targeted, and verified.

Change-by-Change Findings

src/lib/issue-lane.ts (-76 lines)

• Removes buildLaneClassificationPrompt() — a prompt builder function that was never called in production
• Removes serializeLaneData() — a JSON serialization helper that was never called in production
• Removes unused lane-config imports (getConfiguredLanes, getDefaultClaimableLane, getEscalationLane, getBacklogLane)
• Keeps classifyLaneFromSignals, parseLaneClassification, validateLaneRecord, and classifyByHeuristics which are live production code

src/lib/issue-lane.test.ts (-93 lines)

• Removes all tests for the two deleted functions (buildLaneClassificationPrompt and serializeLaneData)
• Retains all tests for live functions

Standards Compliance

✅ No agent-specific names in generic docs — The removed prompt builder contained generic routing rules. This is acceptable as the live classifyLaneFromSignals (backed by src/lib/groomer/llm.ts) handles production lane classification.

✅ Code Standards — Dead code removal reduces maintenance burden and drift risk. No errors introduced.

✅ No secrets or build artifacts — Clean removal only.

Linked Issue Fit

Issue PR 507 explicitly identified:

• buildLaneClassificationPrompt and serializeLaneData as dead code (only referenced by their own tests) ✅
• Duplicate of src/lib/groomer/llm.ts creating drift risk ✅
• Fix: delete dead exports + their tests ✅

The PR correctly:

• Removes both dead functions
• Removes their tests
• Preserves classifyLaneFromSignals (the live classifier used by issue-lane.ts and issue-reconciliation)
• Preserves the /lane route's heuristic classifier path

Evidence Provider Findings

No evidence providers configured.

Tool Harness Findings

Tool grep searches confirmed zero production usages of both removed functions:

• buildLaneClassificationPrompt → 0 matches
• serializeLaneData → 0 matches
• Both combined → 0 matches

This confirms these were genuinely dead exports.

CI Verification

All CI checks passed: Docker Build, Tests (193 passing), Build, Lint, Typecheck. All terminal, authoritative.

Unknowns / Needs Verification

None. The diff is clean, tests pass, grep confirms no remaining usages, and the PR body correctly scopes what was preserved.

Findings

None — all checks pass.