refactor(main): modularize runtime and harden anilist setup flow

backlog/tasks/task-85 - Refactor-large-files-for-maintainability-and-readability.md

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+---
+id: TASK-85
+title: Refactor large files for maintainability and readability
+status: In Progress
+assignee: []
+created_date: '2026-02-19 09:46'
+updated_date: '2026-02-19 10:01'
+labels:
+  - architecture
+  - refactor
+  - maintainability
+dependencies: []
+priority: medium
+---
+
+## Description
+
+<!-- SECTION:DESCRIPTION:BEGIN -->
+Several core files are oversized and high-coupling (`src/main.ts`, `src/anki-integration.ts`, `src/config/service.ts`, `src/core/services/immersion-tracker-service.ts`). This task tracks phased, behavior-preserving decomposition plus guardrails and generated-launcher workflow cleanup.
+<!-- SECTION:DESCRIPTION:END -->
+
+## Suggestions
+
+<!-- SECTION:SUGGESTIONS:BEGIN -->
+- Use seam tests before each extraction.
+- Keep `src/main.ts` + `src/anki-integration.ts` as thin composition/coordinator layers.
+- Formalize `subminer` as generated artifact only.
+<!-- SECTION:SUGGESTIONS:END -->
+
+## Action Steps
+
+<!-- SECTION:PLAN:BEGIN -->
+1. Add file-budget guardrails and baseline report.
+2. Split `src/main.ts` into runtime domain modules.
+3. Split `src/anki-integration.ts` into focused collaborators.
+4. Split `src/config/service.ts` by load/migrate/validate/warn phases.
+5. Split immersion tracker service by state, persistence, sync responsibilities.
+6. Clarify generated launcher artifact workflow and docs.
+7. Run full build/test gate and publish maintainability report.
+<!-- SECTION:PLAN:END -->
+
+## Acceptance Criteria
+<!-- AC:BEGIN -->
+- [ ] #1 `src/main.ts` reduced to orchestration-focused module with extracted runtime domains
+- [ ] #2 `src/anki-integration.ts` reduced to facade with helper collaborators
+- [ ] #3 Config and immersion tracker services decomposed without behavior regressions
+- [ ] #4 `subminer` generated artifact ownership/workflow documented and enforced
+- [ ] #5 Full build + config/core tests pass after refactor
+<!-- AC:END -->
+
+## Definition of Done
+<!-- DOD:BEGIN -->
+- [ ] #1 Plan at `docs/plans/2026-02-19-repo-maintainability-refactor-plan.md` executed or decomposed into child tasks
+- [ ] #2 Regression coverage added for extracted seams
+- [ ] #3 Docs updated for architecture and contributor workflow changes
+<!-- DOD:END -->