feat(hooks): implement session:start and session:end lifecycle events

- Add session:end event triggered before /new or /reset clears the session
- Add session:start event triggered when a new session begins
- Update docs to reflect implemented session lifecycle events

Events include context for:
- sessionEntry, sessionId, sessionFile
- commandSource, senderId
- reason (for session:end) / isReset (for session:start)
- cfg for hook access to config

docs/hooks.md

@@ -235,6 +235,15 @@ Triggered when the gateway starts:
 
 - **`gateway:startup`**: After channels start and hooks are loaded
 
+### Session Events
+
+Triggered during session lifecycle:
+
+- **`session:start`**: When a new session begins (after `/new`, `/reset`, or first message from a new sender)
+  - Context includes: `sessionEntry`, `sessionId`, `sessionFile`, `commandSource`, `senderId`, `isReset` (true if triggered by reset command), `cfg`
+- **`session:end`**: When a session ends (before `/new` or `/reset` clears the session)
+  - Context includes: `sessionEntry` (previous session), `sessionId`, `sessionFile`, `commandSource`, `senderId`, `reason` ("reset"), `cfg`
+
 ### Tool Result Hooks (Plugin API)
 
 These hooks are not event-stream listeners; they let plugins synchronously adjust tool results before Moltbot persists them.
@@ -244,9 +253,6 @@ These hooks are not event-stream listeners; they let plugins synchronously adjus
 ### Future Events
 
 Planned event types:
-
-- **`session:start`**: When a new session begins
-- **`session:end`**: When a session ends
 - **`agent:error`**: When an agent encounters an error
 - **`message:sent`**: When a message is sent
 - **`message:received`**: When a message is received

src/auto-reply/reply/commands-core.ts

@@ -71,6 +71,21 @@ export async function handleCommands(params: HandleCommandsParams): Promise<Comm
   // Trigger internal hook for reset/new commands
   if (resetRequested && params.command.isAuthorizedSender) {
     const commandAction = resetMatch?.[1] ?? "new";
+
+    // Trigger session:end for the previous session before reset
+    if (params.previousSessionEntry) {
+      const sessionEndEvent = createInternalHookEvent("session", "end", params.sessionKey ?? "", {
+        sessionEntry: params.previousSessionEntry,
+        sessionId: params.previousSessionEntry.sessionId,
+        sessionFile: params.previousSessionEntry.sessionFile,
+        commandSource: params.command.surface,
+        senderId: params.command.senderId,
+        reason: "reset", // Session ended due to /new or /reset command
+        cfg: params.cfg,
+      });
+      await triggerInternalHook(sessionEndEvent);
+    }
+
     const hookEvent = createInternalHookEvent("command", commandAction, params.sessionKey ?? "", {
       sessionEntry: params.sessionEntry,
       previousSessionEntry: params.previousSessionEntry,

src/auto-reply/reply/get-reply.ts

@@ -18,6 +18,7 @@ import { resolveDefaultModel } from "./directive-handling.js";
 import { resolveReplyDirectives } from "./get-reply-directives.js";
 import { handleInlineActions } from "./get-reply-inline-actions.js";
 import { runPreparedReply } from "./get-reply-run.js";
+import { createInternalHookEvent, triggerInternalHook } from "../../hooks/internal-hooks.js";
 import { finalizeInboundContext } from "./inbound-context.js";
 import { initSessionState } from "./session.js";
 import { applyResetModelOverride } from "./session-reset-model.js";
@@ -126,6 +127,20 @@ export async function getReplyFromConfig(
     bodyStripped,
   } = sessionState;
 
+  // Trigger session:start for new sessions
+  if (isNewSession) {
+    const sessionStartEvent = createInternalHookEvent("session", "start", sessionKey, {
+      sessionEntry,
+      sessionId,
+      sessionFile: sessionEntry.sessionFile,
+      commandSource: finalized.Surface ?? finalized.Provider,
+      senderId: finalized.From,
+      isReset: resetTriggered, // True if session started due to /new or /reset
+      cfg,
+    });
+    await triggerInternalHook(sessionStartEvent);
+  }
+
   await applyResetModelOverride({
     cfg,
     resetTriggered,