refactor(architecture): enforce module boundaries - #153

Summary

1.6.1 already carries docs/architecture.md and docs/bug-fix-guidelines.md (the MUST/MUST NOT module-boundary contract), but the code hadn't fully caught up to it yet, and CLAUDE.md still described the pre-refactor shape. This PR makes the code satisfy that contract before more bug fixes land and drift further from it — it is not a general cleanup pass. Scope is capped to what's listed below; see "Explicitly out of scope" for what's deliberately deferred.

• main.ts as a real composition/lifecycle root — extracted src/runtime/createSyncRuntime.ts to own the sync-domain + Source Control application constructor graph (SyncManager, SyncStatusRefreshService, SyncDiffService, SyncWorkspace, ChangeRepository, SyncSelectionStore, OperationState, RefreshState, SourceControlViewModel, SourceControlActionService). main.ts now only knows Obsidian lifecycle: settings load/save, view/command/ribbon registration, vault event registration.
• Split SyncStatusRefreshService (was 661 lines, three algorithms in one class) into SyncFileDiscovery, SyncStatusResolver, and RenameReconciler, each with a single owning responsibility. SyncStatusRefreshService now only orchestrates discovery → resolve → reconcile → publish, plus the incremental create/modify/delete/rename handlers (deliberately not split further — see scope below).
• SourceControlView low-risk extraction — pulled the "Sync Queue" and "Repository Changes" regions into SyncQueueSection/RepositoryChangesSection, matching the existing FilterMenu/SourceControlHeader pattern (pure functions: state + callbacks in, never SyncWorkspace/SourceControlActionService/SourceControlViewModel directly).
• SyncWorkspace boundary audit — git grep across src/ui/** and src/logic/source-control/** found the boundary already intact (no UI code touches SyncWorkspace/coordinators directly; the one PushCoordinator hit is a pre-existing type-only import). No code fix needed for the UI → sync direction.
• ESLint boundary guards (eslint.config.mts) — new no-restricted-imports rules: src/ui/** and src/logic/source-control/** may not import a concrete Git provider or a push/pull coordinator/executor directly; src/logic/sync/** may not import src/ui/source-control/**.
• Real violation caught by the new rule — the last rule surfaced a genuine pre-existing reverse dependency: SyncDiffService/SyncInteractionPort (sync domain) imported computeDiffStat/DiffStatLoadResult from ui/source-control. Moved the pure diff-stat computation and the DiffStatLoadResult contract into a new src/logic/sync/DiffStat.ts; the UI now depends on the domain for these, not the reverse.
• Tests — new SyncFileDiscovery.test.ts, SyncStatusResolver.test.ts, RenameReconciler.test.ts, createSyncRuntime.test.ts, DiffStat.test.ts (net-new coverage — the old SyncStatusRefreshService.test.ts only covered incremental handlers, not discovery/resolution/rename-reconciliation directly).
• Docs — CLAUDE.md's "Code Architecture" section replaced with a short contract pointing at docs/architecture.md/docs/bug-fix-guidelines.md (also fixed stale GitLab/GitHub-only provider list → GitHub/GitLab/Gitea, and the single-file sync-manager.ts description). docs/architecture.md's module table and "Current hotspots" section updated to describe the merged code.

Explicitly out of scope (per plan)

No PushCoordinator/PullCoordinator split, no SyncManager rewrite, no provider/BaseGitService cleanup, no settings restructure, no ChangeItem rewrite, no CSS/UX changes, no sync semantics changes, no new features, no version bump, no DI framework, no command/event bus, no create/modify/delete/rename per-event handler classes.

Verification

• npx eslint . — 0 errors (verified after every commit, including the new boundary-guard rules actually firing on the real violation above before the fix).
• npx vitest run — 74 files / 933 tests passed (up from 73 files / 917 tests on 1.6.1; net-new coverage, no regressions).
• npm run build (tsc -noEmit + Obsidian 1.11.0 compat typecheck + esbuild production) — passed after every commit.
• Boundary re-audit after the split: git grep -n "SyncWorkspace" -- src/ui → only doc-comment mentions. git grep -n "PushCoordinator\|PullCoordinator" -- src/ui src/logic/source-control → only the pre-existing type-only import.

DoD checklist

• CLAUDE.md 與 docs/architecture.md 一致
• main.ts 不再組裝整個 Source Control/Sync constructor graph
• SyncStatusRefreshService 不再自己實作 discovery algorithm
• status classification 有明確 owner (SyncStatusResolver)
• rename reconciliation 有明確 owner (RenameReconciler)
• Source Control execution 全部經 SyncWorkspace（audit：本來就成立）
• UI 沒有 concrete provider dependency
• sync domain 沒有 Source Control UI dependency（新規則抓到並修正了既有違規）
• ESLint 能阻止上述 dependency regression
• SourceControlView 明顯降低責任密度
• existing sync semantics 不變
• unit tests green
• build/lint green
• GitHub/GitLab/Gitea E2E green — not run this session (needs provisioned credentials); no sync semantics changed, so not expected to be affected, but flagging as unverified.

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