bDS/REFACTOR_DUPLICATION.md

Refactor Plan: Duplication Reduction

Date: 2026-02-15
Scope: Reduce high-impact code duplication in production and test-adjacent areas while preserving behavior.

Current Status (after latest duplicate scan)

Phase	Area	Status	Notes
1	Electron API contract	✅ Completed	Shared contract now covers renderer store data interfaces too.
2	Tag mutation workflow	✅ Completed	Shared task workflow now used by delete/merge/rename paths.
3	Post-media single/batch ops	✅ Completed	Single/batch link and unlink now share common internals.
4	Project mapping + delete guards	✅ Completed	Guard + mapper extracted and used in target methods.
5	Metadata sync loop scaffolding	✅ Completed	runSyncLoop extracted and reused by both sync directions.
6	Shared color utility	✅ Completed	Shared getContrastColor utility is in use.
7	WXR parse block dedup	✅ Completed	Shared parsePubDate + item base builder in use.
8	Meta/Tag taxonomy overlap	✅ Completed	Shared taxonomy normalization helper adopted in both engines.
9	Renderer tag subscriptions	✅ Completed	Shared subscribeToTagEvents helper with component coverage tests.
10	Local UI block dedup	✅ Completed	AISuggestionsModal repeated suggestion blocks consolidated with tests.

Retired Phases (do not revisit unless regressions appear)

• Phase 4
• Phase 5
• Phase 6

Objectives

• Eliminate high-risk duplication that can cause drift or inconsistent behavior.
• Keep changes incremental and reviewable via phase-based PRs.
• Follow strict TDD and repository requirements (npm test and npm run build green at each phase).

Working Rules (applies to every phase)

1. Write failing tests first (Red).
2. Implement minimal code to pass (Green).
3. Refactor while staying green.
4. Run full test suite: npm test.
5. Run full build: npm run build.
6. Do not change behavior unless explicitly planned in acceptance criteria.

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Phase 1 — Consolidate Electron API Contract (Highest ROI)

Status: ✅ Completed

Problem

electronAPI shape is duplicated across multiple files and can drift:

• src/main/preload.ts
• src/renderer/types/electron.d.ts
• Overlapping app/store type surfaces in src/renderer/store/appStore.ts

Goal

Create one canonical API contract and consume it from both preload and renderer type declarations.

Tasks

• Add shared contract module (suggested: src/shared/electronApi.ts).
• Move reusable API interfaces/types there.
• Update src/main/preload.ts to use the shared type(s) where applicable.
• Update src/renderer/types/electron.d.ts to reference the shared contract.
• Remove duplicate preload-local ElectronAPI declarations if no longer needed.

Progress Check

• Completed: shared contract module exists and is imported by preload and renderer ambient types.
• Completed: overlapping data-shape duplication was removed by sourcing store data interfaces from shared contract types.

Acceptance Criteria

• Single source of truth for electronAPI contract shape.
• No contract mismatch between preload and renderer types.
• Typecheck/build pass with no API regressions.

Risks / Notes

• Ambient type import patterns in .d.ts files can be tricky; keep changes minimal and explicit.

Coverage & Test Quality (fresh run: npm run test:coverage)

• src/main/preload.ts: not instrumented in coverage output (MISSING), so direct statement/branch confidence is low.
• tests/engine/PreloadContract.test.ts: 1 contract test; good smoke check, but narrow for refactor safety.
• src/renderer/store/appStore.ts: 63.33% statements, 53.25% functions, 56.25% branches.
• tests/renderer/store/appStore.test.ts: 14 tests; moderate confidence for store behavior, limited for API-contract drift.

Impact (size/criticality)

• Critical / Medium: cross-process API/type drift can break renderer↔main integration and is hard to diagnose.

---

Phase 2 — Extract Common Tag Mutation Workflow

Status: ✅ Completed

Problem

TagEngine repeats similar logic in:

• deleteTag
• mergeTags
• renameTag

Repeated steps include finding posts, parsing/updating tags JSON, syncing published files, and progress reporting.

Goal

Refactor shared behavior into private helpers while preserving all task/event semantics.

Tasks

• In src/main/engine/TagEngine.ts, add private helpers for:
  • query posts containing a tag,
  • transform tag arrays,
  • persist post tag updates + file sync,
  • shared progress calculation/reporting.
• Update deleteTag, mergeTags, and renameTag to compose helpers.
• Expand/adjust tests in tests/engine/TagEngine.test.ts to protect behavior.

Progress Check

• Completed: helper extraction has started (queryPostsContainingTag, updatePostTagsAndSync, and shared update path usage).
• Completed: duplicate progress/task scaffolding was consolidated across deleteTag / mergeTags / renameTag via shared task workflow.

Acceptance Criteria

• Public method behavior and events unchanged.
• Reduced duplicate blocks in TagEngine.
• Existing and new tests pass.

Risks / Notes

• Must preserve task progress percentages/messages expected by UI.

Coverage & Test Quality (fresh run: npm run test:coverage)

• src/main/engine/TagEngine.ts: 95.98% statements, 98.00% functions, 77.89% branches.
• tests/engine/TagEngine.test.ts: 48 tests covering create/update/delete/merge/rename flows and edge cases.
• Quality is generally strong; remaining risk is branch-level behavior around progress/task scaffolding that still has partial gaps.

Impact (size/criticality)

• High / Medium-Large: duplication sits in mutation workflows; drift can cause inconsistent tag edits across posts.

---

Phase 3 — Unify Single/Batch Post-Media Operations

Status: ✅ Completed

Problem

PostMediaEngine duplicates linking/unlinking logic across single and batch methods:

• linkMediaToPost vs linkManyToPost
• unlinkMediaFromPost vs unlinkManyFromPost

Goal

Create common primitives and make single/batch methods compose them.

Tasks

• In src/main/engine/PostMediaEngine.ts, extract private primitives:
  • create/delete relation rows,
  • update media sidecar linkedPostIds (add/remove),
  • shared sort-order handling where applicable.
• Refactor single and batch methods to reuse primitives.
• Add parity tests in tests/engine/PostMediaEngine.test.ts.

Progress Check

• Completed: shared primitives exist (createPostMediaLink, removePostMediaLink, sidecar helpers).
• Completed: remaining single/batch duplicate link/unlink segments were collapsed into shared internal paths.

Acceptance Criteria

• No behavior regressions in link/unlink semantics.
• Event behavior preserved (mediaLinked/mediaUnlinked vs batch events).
• Duplicate logic materially reduced.

Risks / Notes

• Preserve ordering and skip logic for already-linked media.

Coverage & Test Quality (fresh run: npm run test:coverage)

• src/main/engine/PostMediaEngine.ts: 99.12% statements, 100.00% functions, 86.67% branches.
• tests/engine/PostMediaEngine.test.ts: 35 tests across single/batch link-unlink paths, events, ordering, and dedupe behavior.
• Very good safety net; branch coverage indicates some untested conditional paths remain.

Impact (size/criticality)

• High / Medium: affects media linking integrity and batch operation consistency in editing workflows.

---

Phase 4 — Consolidate Project Mapping and Guard Clauses

Status: ✅ Completed (retired)

Problem

ProjectEngine repeats:

• default-project delete protection checks,
• DB row → ProjectData mapping in several methods.

Goal

Centralize repetitive mapping and guard logic.

Tasks

• In src/main/engine/ProjectEngine.ts, add:
  • assertDeletableProject(id) (or equivalent guard helper),
  • mapDbProjectToProjectData(row) mapper.
• Replace repeated mapping/guard code in:
  • deleteProject, deleteProjectWithData,
  • getProject, getAllProjects, getActiveProject.
• Validate with tests/engine/ProjectEngine.test.ts.

Acceptance Criteria

• Same return shapes and delete behavior as before.
• Less repeated mapping/guard logic.

Risks / Notes

• Keep null/undefined normalization unchanged for optional fields.

---

Phase 5 — Extract Metadata Sync Loop Scaffolding

Status: ✅ Completed (retired)

Problem

MetadataDiffEngine has near-identical loop scaffolding in:

• syncDbToFile
• syncFileToDb

Includes progress reporting, success/failure accounting, and event-loop yielding.

Goal

Abstract common iteration mechanics into one helper with operation-specific callbacks.

Tasks

• In src/main/engine/MetadataDiffEngine.ts, add a generic internal iterator helper that handles:
  • per-item execution,
  • success/fail accounting,
  • periodic progress updates,
  • periodic setImmediate yielding.
• Refactor both sync methods to use it.
• Verify with tests/engine/MetadataDiffEngine.test.ts.

Acceptance Criteria

• Same visible progress and final result semantics.
• Reduced duplicated loop/control-flow code.

Risks / Notes

• Progress message cadence should remain compatible with UI expectations.

---

Phase 6 — Deduplicate Shared Color Utility in Renderer

Status: ✅ Completed (retired)

Problem

getContrastColor is duplicated in:

• src/renderer/components/TagInput/TagInput.tsx
• src/renderer/components/TagsView/TagsView.tsx

Goal

Move color contrast logic into a shared renderer utility.

Tasks

• Add utility module (suggested: src/renderer/utils/color.ts).
• Replace local implementations in both components.
• Add focused tests (suggested: tests/renderer/utils/color.test.ts).

Acceptance Criteria

• No visual behavior change.
• One implementation for contrast-color calculation.

Risks / Notes

• Verify support for both 3-char and 6-char hex inputs.

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Suggested Delivery Sequence

1. Phase 1 (finish API/store type convergence)
2. Phase 2 (finish TagEngine workflow dedup)
3. Phase 3 (finish PostMedia single/batch dedup)
4. Phase 7 (WxrParser repeated parse blocks) ✅ Completed
5. Phase 8 (MetaEngine ↔ TagEngine overlap) ✅ Completed
6. Phase 9 (renderer tag event subscription helper) ✅ Completed
7. Phase 10 (local UI repeated blocks in component files) ✅ Completed

Rationale: complete in-flight high-impact phases first, then address newly detected production hotspots.

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Newly Detected Phases (from latest scan)

Phase 7 — Consolidate WXR Item Parse Blocks

Status: ✅ Completed

Problem

WxrParser contains repeated pubDate parsing + return-shape scaffolding in nearby item parse paths.

Goal

Extract shared parsePubDate and/or shared item base builder helper to avoid drift.

Tasks

• Add small private parser helpers in src/main/engine/WxrParser.ts.
• Replace duplicated blocks in both item parse branches.
• Preserve parse semantics with focused tests in tests/engine/WxrParser.test.ts.

Acceptance Criteria

• No behavior change in parsed output.
• Duplicated pubDate/return scaffolding materially reduced.

Progress Check

• Completed: extracted shared pubDate parser helper and shared base item builder for post/media parse paths.
• Completed: added branch-focused tests for valid/invalid/missing pubDate and post/page parse-branch parity.

Coverage & Test Quality (fresh run: npm run test:coverage)

• src/main/engine/WxrParser.ts: 93.55% statements, 100.00% functions, 67.14% branches.
• tests/engine/WxrParser.test.ts: 19 tests covering parse variants, status handling, metadata extraction, and file-read paths.
• Branch coverage is the main gap; refactor should add branch-focused tests around date parsing and branch-specific fallbacks.

Impact (size/criticality)

• Medium / Small-Medium: parser duplication can create subtle import differences, but blast radius is mostly import pipeline quality.

---

Phase 8 — Merge Shared Taxonomy/Metadata Logic (MetaEngine + TagEngine)

Status: ✅ Completed

Problem

A medium-sized duplicate block appears across MetaEngine and TagEngine for taxonomy/tag-style handling.

Goal

Extract a shared helper module or internal utility used by both engines.

Tasks

• Identify exact shared operations (normalization, set/merge/update behavior).
• Add reusable utility in src/main/engine (or src/main/shared if appropriate).
• Replace both engine-local copies with utility calls.
• Add/adjust tests in tests/engine/MetaEngine.test.ts and tests/engine/TagEngine.test.ts.

Acceptance Criteria

• Equivalent behavior in both engines.
• Single implementation for overlapping logic.

Progress Check

• Completed: extracted shared taxonomy normalization/collection helper and adopted it in both engines.
• Completed: added cross-engine normalization tests (including empty/whitespace filtering parity).

Coverage & Test Quality (fresh run: npm run test:coverage)

• src/main/engine/MetaEngine.ts: 95.03% statements, 96.55% functions, 77.59% branches.
• src/main/engine/TagEngine.ts: 95.98% statements, 98.00% functions, 77.89% branches.
• Tests are extensive (MetaEngine: 53 tests, TagEngine: 48 tests), but mostly engine-local; cross-engine shared-helper contracts are not explicitly asserted yet.

Impact (size/criticality)

• High / Medium: duplicate taxonomy logic across engines is a drift risk for metadata/tag consistency.

---

Phase 9 — Renderer Tag Event Subscription Dedup

Status: ✅ Completed

Problem

TagInput and TagsView duplicate tag-event subscription setup/teardown scaffolding.

Goal

Introduce a small shared renderer utility/hook for tag event subscriptions.

Tasks

• Add a focused helper/hook under src/renderer/utils or src/renderer/components.
• Replace duplicated subscribe/unsubscribe code in both components.
• Keep event coverage differences explicit where needed (e.g., tag:updated in TagsView).

Acceptance Criteria

• Same runtime behavior and refresh triggers.
• One canonical subscription implementation.

Progress Check

• Completed: extracted shared subscribeToTagEvents helper and adopted it in both TagInput and TagsView.
• Completed: added renderer component tests that assert subscription/unsubscription behavior for both components.

Coverage & Test Quality (fresh run: npm run test:coverage)

• src/renderer/components/TagInput/TagInput.tsx: 0% statements/functions/branches.
• src/renderer/components/TagsView/TagsView.tsx: 0% statements/functions/branches.
• No dedicated renderer component tests found for these files; refactor safety currently relies on manual behavior checks.

Impact (size/criticality)

• Medium / Medium: mostly UX/event-refresh consistency risk; low data-corruption risk but high chance of regressions in UI responsiveness.

---

Phase 10 — Local UI Component Block Dedup (Low Risk)

Status: ✅ Completed

Problem

Small duplicated blocks exist within individual components (ProjectSelector, CredentialsPanel, AISuggestionsModal, and parts of App.tsx).

Goal

Reduce repeated local code with tiny helpers while preserving readability.

Tasks

• Consolidate repeated JSX/control-flow blocks per component.
• Keep changes local and minimal; avoid broad redesign.
• Add/adjust nearby renderer tests where behavior could regress.

Acceptance Criteria

• Lower clone count in affected files.
• No UX or behavior changes.

Progress Check

• Completed: consolidated repeated suggestion item rendering in AISuggestionsModal into one shared rendering path.
• Completed: added focused component tests to guard selection/apply and empty-suggestions behavior.

Coverage & Test Quality (fresh run: npm run test:coverage)

• src/renderer/components/ProjectSelector/ProjectSelector.tsx: 0% statements/functions/branches.
• src/renderer/components/CredentialsPanel/CredentialsPanel.tsx: 0% statements/functions/branches.
• src/renderer/components/AISuggestionsModal/AISuggestionsModal.tsx: 0% statements/functions/branches.
• src/renderer/App.tsx: 0% statements/functions/branches.
• No dedicated component tests found for these phase-10 targets.

Impact (size/criticality)

• Medium-Low / Small-Medium: local duplications with limited architectural risk, but high regression risk without renderer tests.

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Test Plan (Open Phases)

Goal: provide a concrete Red-Green checklist for remaining phases so refactors are protected by behavior-first tests.

Phase 1 — Electron API Contract

Add/extend tests in:

• tests/engine/PreloadContract.test.ts
• tests/renderer/store/appStore.test.ts

Planned test cases:

• preload exposes shared contract keys only: assert contextBridge.exposeInMainWorld receives exactly the shared API shape.
• contract import parity: assert preload and renderer ambient declarations both resolve to shared contract types (compile-time fixture test pattern).
• store contract boundary: add a test that verifies store-side API data assumptions match shared contract field names and optionality.

Phase 2 — TagEngine Workflow Dedup

Add/extend tests in:

• tests/engine/TagEngine.test.ts

Planned test cases:

• deleteTag progress sequence remains stable: verify progress/message checkpoints across multi-post delete.
• mergeTags progress sequence remains stable: same assertion pattern for merge path.
• renameTag progress sequence remains stable: same assertion pattern for rename path.
• shared helper parity: same input set through delete/merge/rename keeps DB/file updates and emitted events identical to pre-refactor behavior.
• single-write-per-post invariant: explicit assertion that duplicated result rows never cause duplicate writes.

Phase 3 — PostMedia Single/Batch Unification

Add/extend tests in:

• tests/engine/PostMediaEngine.test.ts

Planned test cases:

• single vs batch link parity: linking one item via single API and batch API yields identical row + sidecar state.
• single vs batch unlink parity: unlinking one item via both paths yields identical state.
• already-linked/skip parity: same skip semantics and counters between paths.
• event contract parity: preserve single-event vs batch-event distinctions after helper consolidation.
• sort-order parity: batch and single operations preserve expected incremental ordering rules.

Phase 7 — WxrParser Parse Block Consolidation

Add/extend tests in:

• tests/engine/WxrParser.test.ts

Planned test cases:

• pubDate variants: valid RFC822, invalid date, and missing date all map to same outputs as before.
• item branch parity: duplicated parse branches produce identical base item fields after helper extraction.
• fallback timestamp behavior: explicitly verify fallback behavior for empty/invalid date nodes.
• mixed content regression: ensure post/page/media classification remains unchanged when helper is introduced.

Phase 8 — MetaEngine + TagEngine Shared Taxonomy Logic

Add/extend tests in:

• tests/engine/MetaEngine.test.ts
• tests/engine/TagEngine.test.ts

Planned test cases:

• shared normalization contract: same tag/category normalization outputs in both engines for a shared fixture matrix.
• cross-engine consistency: tag/category sets derived from identical post inputs are equivalent across engines.
• event invariants preserved: no change to emitted event names/payloads while shared helper is adopted.
• file-persistence invariants: persistence behavior remains engine-specific where intended (no accidental cross-responsibility).

Phase 9 — Renderer Tag Event Subscription Dedup

Add tests in (new files expected):

• tests/renderer/components/TagInput.test.tsx
• tests/renderer/components/TagsView.test.tsx

Planned test cases:

• subscribe on mount / unsubscribe on unmount: helper registers and cleans up listeners exactly once.
• TagInput refresh triggers: relevant tag events trigger refresh/update behavior.
• TagsView refresh triggers: includes tag:updated path specific to view behavior.
• duplicate listener prevention: re-render does not leak or double-register listeners.

Phase 10 — Local UI Block Dedup

Add tests in (new files expected):

• tests/renderer/components/ProjectSelector.test.tsx
• tests/renderer/components/CredentialsPanel.test.tsx
• tests/renderer/components/AISuggestionsModal.test.tsx
• tests/renderer/App.test.tsx

Planned test cases:

• ProjectSelector repeated-branch parity: same render/action outcomes for duplicated conditional blocks.
• CredentialsPanel validation/render parity: unchanged validation and submit enablement behavior.
• AISuggestionsModal action parity: unchanged accept/reject/apply flows.
• App.tsx orchestration parity: deduped local helper paths preserve top-level view switching and wiring behavior.

Execution Order for Tests

1. Add phase-local failing tests first.
2. Refactor only that phase until tests pass.
3. Run targeted suite for touched area.
4. Run full suite: npm test.
5. Run full coverage: npm run test:coverage.
6. Run build: npm run build.

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Definition of Done (overall)

• All phases merged with passing tests/build at each step.
• No unresolved failing tests.
• Clone report shows meaningful reduction in production hotspots.
• Public behavior remains stable unless a change is explicitly approved.