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

packages/app/e2e/global-setup.ts

@@ -537,13 +537,22 @@ async function awaitRelayReady(
   }
 }
 
-async function startRelay(): Promise<number> {
+async function getAvailablePortExcluding(excludedPorts: Set<number>): Promise<number> {
+  for (;;) {
+    const port = await getAvailablePort();
+    if (!excludedPorts.has(port)) {
+      return port;
+    }
+  }
+}
+
+async function startRelay(excludedPorts: Set<number>): Promise<number> {
   const relayDir = path.resolve(__dirname, "..", "..", "relay");
   const maxRelayStartupAttempts = 5;
   let lastRelayStartupError: unknown = null;
 
   for (let attempt = 1; attempt <= maxRelayStartupAttempts; attempt += 1) {
-    const relayPort = await getAvailablePort();
+    const relayPort = await getAvailablePortExcluding(excludedPorts);
     const buffer = createLineBuffer();
     const state: RelayStreamState = { failureLine: null, readyForSelectedPort: false };
 
@@ -729,7 +738,7 @@ export default async function globalSetup() {
   const dictation = await resolveDictationConfig();
 
   try {
-    const relayPort = await startRelay();
+    const relayPort = await startRelay(new Set([port, metroPort]));
     metroProcess = startMetro(metroPort, metroLineBuffer);
     daemonProcess = startDaemon({
       port,