fix: guard cliAvailability setState against unmount

Both SpawnAgentDialog and TerminalPane lacked a cancelled flag in the
CLI availability useEffect, allowing setCliAvailability to fire on an
unmounted component if the user closed the pane before the IPC round
trip completed. Pattern matches the existing loadPersonas/loadBurnSummaries
guards in the same files.

https://claude.ai/code/session_01KXU1uAUwx3L82TMLnAmU4z

Author: claude

check_types.mjs

@@ -0,0 +1,25 @@
+// Check if Object.fromEntries result is assignable to Partial<Record<SpawnAgentCli, boolean>>
+
+// According to TypeScript:
+// Partial<Record<SpawnAgentCli, boolean>> expands to:
+// { claude?: boolean; codex?: boolean; opencode?: boolean }
+
+// Object.fromEntries returns: { [k: string]: any }
+// In the context of:
+// const results: Array<[SpawnAgentCli, boolean]> = [['claude', true], ...]
+// Object.fromEntries(results) is typed as: { [k: string]: boolean }
+
+// The question: is { [k: string]: boolean } assignable to 
+// { claude?: boolean; codex?: boolean; opencode?: boolean }?
+
+// Answer: YES, because:
+// 1. { [k: string]: boolean } is an index signature that matches ANY string key
+// 2. { claude?: boolean; codex?: boolean; opencode?: boolean } only uses specific keys
+// 3. Any value with an index signature { [k: string]: T } satisfies a type with specific optional properties
+
+console.log("Type check analysis:");
+console.log("Object.fromEntries(results) type: { [k: string]: boolean }");
+console.log("setCliAvailability expects: Partial<Record<SpawnAgentCli, boolean>>");
+console.log("Which expands to: { claude?: boolean; codex?: boolean; opencode?: boolean }");
+console.log("");
+console.log("TypeScript assignability: YES - index signature types are assignable to property-specific types");

src/renderer/src/components/sidebar/SpawnAgentDialog.tsx

@@ -48,13 +48,15 @@ export function SpawnAgentDialog(): React.ReactNode {
   }, [project, root?.id, selectedRootId])
 
   useEffect(() => {
+    let cancelled = false
     const clis: SpawnAgentCli[] = ['claude', 'codex', 'opencode']
     void Promise.all(clis.map(async (cli) => {
       const available = await pear.broker.checkCliAvailable(cli).catch(() => false)
       return [cli, available] as const
     })).then((results) => {
-      setCliAvailability(Object.fromEntries(results))
+      if (!cancelled) setCliAvailability(Object.fromEntries(results))
     })
+    return () => { cancelled = true }
   }, [])
 
   useEffect(() => {

src/renderer/src/components/terminal/TerminalPane.tsx

@@ -569,13 +569,15 @@ export function TerminalPane(): React.ReactNode {
   }
 
   useEffect(() => {
+    let cancelled = false
     const clis: SpawnAgentCli[] = ['claude', 'codex', 'opencode']
     void Promise.all(clis.map(async (cli) => {
       const available = await pear.broker.checkCliAvailable(cli).catch(() => false)
       return [cli, available] as const
     })).then((results) => {
-      setCliAvailability(Object.fromEntries(results))
+      if (!cancelled) setCliAvailability(Object.fromEntries(results))
     })
+    return () => { cancelled = true }
   }, [])
 
   useEffect(() => {