SubMiner/backlog/tasks/task-154 - Avoid-merged-dictionary-rebuilds-on-MRU-reorder-only-revisits.md

id, title, status, assignee, created_date, updated_date, labels, dependencies, references, documentation, priority, ordinal

id	title	status	assignee	created_date	updated_date	labels	dependencies	references	documentation	priority	ordinal
TASK-154	Avoid merged dictionary rebuilds on MRU reorder-only revisits	Done	@codex	2026-03-10 09:16	2026-03-16 05:13	character-dictionary yomitan anilist		/home/sudacode/projects/japanese/SubMiner/src/main/runtime/character-dictionary-auto-sync.ts /home/sudacode/projects/japanese/SubMiner/src/main/runtime/character-dictionary-auto-sync.test.ts /home/sudacode/projects/japanese/SubMiner/src/main/character-dictionary-runtime.ts /home/sudacode/projects/japanese/SubMiner/src/main/character-dictionary-runtime.test.ts	/home/sudacode/projects/japanese/subminer-docs/development.md /home/sudacode/projects/japanese/subminer-docs/architecture.md	high	31500

Description

Keep per-title MRU retention ordering for eviction decisions, but do not rebuild or reimport the merged character dictionary when the retained set membership is unchanged and only the MRU order changes.

Acceptance Criteria

• #1 Revisiting an anime already inside the retained set updates MRU ordering used for later eviction decisions without rebuilding or reimporting the merged dictionary when retained membership is unchanged.
• #2 Merged dictionary revisions and contents are stable for the same retained membership regardless of MRU ordering.
• #3 Adding a new anime that changes retained membership still rebuilds and imports the merged dictionary with the correct eviction behavior.
• #4 Regression tests cover reorder-only revisits and stable merged revisions for equivalent retained sets.

Implementation Plan

1. Add a failing auto-sync regression showing that a revisit which only reorders MRU state should update activeMediaIds but skip merged rebuild/import.
2. Add a runtime-level regression showing buildMergedDictionary produces a stable revision for equivalent retained memberships regardless of input order.
3. Update merged-dictionary build normalization and auto-sync rebuild gating so rebuilds are driven by retained membership changes (or snapshot changes), not MRU reordering alone.
4. Re-run focused dictionary tests plus the local verification lanes impacted by the change.

Implementation Notes

Changed src/main/runtime/character-dictionary-auto-sync.ts so MRU order still updates in activeMediaIds, but merged rebuild/import now keys off retained membership changes rather than order-only reordering. Order-only revisits no longer force a merged ZIP rewrite or Yomitan reimport.

Changed src/main/character-dictionary-runtime.ts to canonicalize merged dictionary media ids before building, which makes merged revisions stable for equivalent retained memberships regardless of MRU ordering.

Updated regression coverage in src/main/runtime/character-dictionary-auto-sync.test.ts for reorder-only revisits and membership-change rebuilds, and extended src/main/character-dictionary-runtime.test.ts to assert stable merged revisions for reordered inputs. Verified with bun test src/main/runtime/character-dictionary-auto-sync.test.ts src/main/character-dictionary-runtime.test.ts, bun run typecheck, bun run changelog:lint, and bun run test:fast.

Final Summary

Updated merged character-dictionary syncing so MRU ordering is still tracked for eviction in src/main/runtime/character-dictionary-auto-sync.ts, but reorder-only revisits no longer rebuild or reimport the merged dictionary unless retained membership or snapshot data changes. Canonicalized merged build input ordering in src/main/character-dictionary-runtime.ts so revisions remain stable for the same retained set regardless of MRU order, and added regressions in src/main/runtime/character-dictionary-auto-sync.test.ts plus src/main/character-dictionary-runtime.test.ts. Also updated changes/character-dictionary-mru-state-recovery.md to cover the new behavior.

Validation: bun test src/main/runtime/character-dictionary-auto-sync.test.ts src/main/character-dictionary-runtime.test.ts, bun run typecheck, bun run changelog:lint, bun run test:fast.