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+# Effect Migration Plan (From Current State)
+
+Current status summary:
+- Service contracts, typed errors, and most checkpoint/persistence services exist.
+- `ProviderServiceLive` is already native orchestration (not a thin adapter).
+- Production server path still uses legacy `ProviderManager`/`FilesystemCheckpointStore`.
+- Checkpoint flow now avoids snapshot re-sync and is write-time driven.
+
+## PR 1: Wire Provider/Checkpoint Effect Stack Into `wsServer`
+- Build one runtime layer graph for provider + checkpoint + persistence + orchestration.
+- Resolve `ProviderService` from runtime in `wsServer`.
+- Replace `ProviderManager` method calls in WS handlers with `ProviderService` calls.
+- Forward provider events by subscribing to `ProviderService.subscribeToEvents`.
+- Keep WS method/push payloads identical.
+
+## PR 2: Runtime Composition + Startup Ownership
+- Create/centralize `AppLive` composition for server startup.
+- Ensure outer runtime provides Node/platform services once.
+- Ensure migrations run at startup via scoped/layer startup path.
+- Remove ad-hoc service initialization in request-time paths.
+
+## PR 3: Session Lifecycle Hygiene + Checkpoint Invariants
+- Add explicit checkpoint session cleanup on `stopSession` / `stopAll`.
+- Remove per-session lock/cwd map leaks.
+- Keep strict invariant model:
+  - root checkpoint created at session initialization before agent modifications
+  - each completed turn captures filesystem checkpoint and persists metadata
+  - no after-the-fact metadata rebuild/sync
+- Add tests for lifecycle cleanup and invariant-failure surfaces.
+
+## PR 4: Provider Event Stream Hardening (Without Extra Service Fragmentation)
+- Keep `ProviderService` as the public event surface.
+- Internally move callback fanout to Effect concurrency primitives (`Queue`/`PubSub`) for ordering/backpressure control.
+- Keep API as `subscribeToEvents` unless we explicitly choose stream API later.
+- Add tests for ordering and subscriber isolation under load.
+
+## PR 5: Codex Runtime Split (Scoped Effect Core)
+- Extract `CodexAppServerManager` responsibilities into Effect-native layers:
+  - scoped process lifecycle
+  - RPC request/response + pending map via `Deferred`
+  - session registry/state
+- Keep `CodexAdapter` contract stable while swapping internals.
+- Preserve protocol behavior and timeout semantics.
+
+## PR 6: Codex Protocol Decode Hardening
+- Replace ad-hoc unknown parsing with runtime schema decode.
+- Map decode failures to typed tagged errors with `cause` retained.
+- Add regression tests for malformed/partial protocol frames.
+
+## PR 7: Remove Legacy Provider Stack
+- Remove `ProviderManager` + legacy checkpoint integration from runtime path.
+- Remove `FilesystemCheckpointStore` from active server flow (keep only if explicitly needed for compatibility tooling).
+- Update tests to assert only Effect service path is used.
+
+## PR 8: Final Cleanup + Docs
+- Update architecture docs with final layer graph and service boundaries.
+- Document error model and recovery semantics.
+- Trim dead compatibility code and stale plan references.