feat(plugin): add session.creating hook for customizing session creation

packages/opencode/src/session/index.ts

@@ -18,6 +18,7 @@ import { SessionPrompt } from "./prompt"
 import { fn } from "@/util/fn"
 import { Command } from "../command"
 import { Snapshot } from "@/snapshot"
+import { Plugin } from "@/plugin"
 
 import type { Provider } from "@/provider/provider"
 import { PermissionNext } from "@/permission/next"
@@ -136,9 +137,19 @@ export namespace Session {
       })
       .optional(),
     async (input) => {
+      const sessionID = Identifier.ascending("session")
+
+      // Allow plugins to customize session creation (e.g., set custom directory)
+      const creating = await Plugin.trigger(
+        "session.creating",
+        { sessionID, parentID: input?.parentID },
+        { directory: Instance.directory },
+      )
+
       return createNext({
+        id: sessionID,
         parentID: input?.parentID,
-        directory: Instance.directory,
+        directory: creating.directory,
         title: input?.title,
         permission: input?.permission,
       })

packages/plugin/src/index.ts

@@ -204,6 +204,16 @@ export interface Hooks {
       system: string[]
     },
   ) => Promise<void>
+  /**
+   * Called before a session is created. Allows plugins to customize
+   * session creation, including setting a custom working directory.
+   *
+   * - `directory`: The working directory for the session (defaults to Instance.directory)
+   */
+  "session.creating"?: (
+    input: { sessionID: string; parentID?: string },
+    output: { directory: string },
+  ) => Promise<void>
   /**
    * Called before session compaction starts. Allows plugins to customize
    * the compaction prompt.

packages/web/src/content/docs/plugins.mdx

@@ -179,6 +179,7 @@ Plugins can subscribe to events as seen below in the Examples section. Here is a
 
 #### Session Events
 
+- `session.creating`
 - `session.created`
 - `session.compacted`
 - `session.deleted`