Rewind chat or files from any user message (#1154)

* Add Pi extension-launch plumbing for in-process tree primitives

* Add Rewind controls for agent sessions

* Preserve SDK checkpoint env var so Claude file rewind works

The SDK injects CLAUDE_CODE_ENABLE_SDK_FILE_CHECKPOINTING=true when file checkpointing is enabled. The earlier parent-env stripping from c4782ec71c was too broad and removed that child flag along with real parent-session markers.

Keep stripping parent markers, but preserve the checkpoint flag so the SDK rewind path can run directly. With that boundary fixed, the JSONL file-rewind fallback is no longer needed.

* Update OpenCode history replay tests for rewind state

* Show Rewind actions in an adaptive sheet

* Fix rewind semantics across providers

* Refactor Pi IDs through extension capture

* Restore user message to composer after rewind

* Fix Claude rewind tool result mapping

* Fix Claude rewind session switch roundtrip

* Fix rewind and optimistic message regressions

* Tighten rewind test discipline

* Fix OpenCode optimistic message reconciliation

* Reconcile optimistic user messages by marker

* Reorder user message actions

* Unify provider user message contract

* Add Claude rewind flow Playwright contract

* Add Codex rewind flow Playwright contract

* Add OpenCode rewind flow Playwright contract

* Add Pi rewind flow Playwright contract

* Remove real-provider rewind Playwright contracts

* Gate real-provider rewind specs from CI Playwright

docs/testing.md

@@ -111,7 +111,7 @@ Vitest picks up tests by suffix. The suffix tells the runner which category it b
 | `*.real.e2e.test.ts`  | E2E that hits a real provider (Claude/Codex/Copilot/OpenCode/Pi) — needs creds in `packages/server/.env.test` | `npm run test:integration:real` / `test:e2e:real`                                    |
 | `*.local.e2e.test.ts` | E2E that needs a local-only resource                                                                          | `npm run test:integration:local` / `test:e2e:local`                                  |
 
-App-level Playwright browser E2E lives in `packages/app/e2e/*.spec.ts` and runs via `npm run test:e2e --workspace=@getpaseo/app` (separate from Vitest E2E).
+App-level Playwright browser E2E lives in `packages/app/e2e/*.spec.ts` and runs via `npm run test:e2e --workspace=@getpaseo/app` (separate from Vitest E2E). App Playwright specs that hit real providers use `*.real.spec.ts` and run through `npm run test:e2e:real --workspace=@getpaseo/app`; the default app E2E project ignores that suffix so CI does not need provider credentials.
 
 ### Test setup