docs(coding-agent): fix ctx.branch -> ctx.fork in extensions docs

packages/coding-agent/CHANGELOG.md

@@ -860,7 +860,7 @@ The hooks API has been restructured with more granular events and better session
 
 - `ctx.waitForIdle()` - wait for agent to finish streaming
 - `ctx.newSession(options?)` - create new sessions with optional setup callback
-- `ctx.branch(entryId)` - branch from a specific entry
+- `ctx.fork(entryId) - fork from a specific entry, creating a new session file
 - `ctx.navigateTree(targetId, options?)` - navigate the session tree
 
 These methods are only on `HookCommandContext` (not `HookContext`) because they can deadlock if called from event handlers that run inside the agent loop.

packages/coding-agent/docs/extensions.md

@@ -715,14 +715,14 @@ if (result.cancelled) {
 }
 ```
 
-### ctx.branch(entryId)
+### ctx.fork(entryId)
 
-Branch from a specific entry:
+Fork from a specific entry, creating a new session file:
 
 ```typescript
-const result = await ctx.branch("entry-id-123");
+const result = await ctx.fork("entry-id-123");
 if (!result.cancelled) {
-  // Now in the branched session
+  // Now in the forked session
 }
 ```