fix: resolve Gemini CLI 0.37.0 session capture failures (#1664) (#1692)

Three root causes prevented Gemini sessions from persisting prompts,
observations, and summaries:

1. BeforeAgent was mapped to user-message (display-only) instead of
   session-init (which initialises the session and starts the SDK agent).

2. The transcript parser expected Claude Code JSONL (type: "assistant")
   but Gemini CLI 0.37.0 writes a JSON document with a messages array
   where assistant entries carry type: "gemini". extractLastMessage now
   detects the format and routes to the correct parser, preserving
   full backward compatibility with Claude Code JSONL transcripts.

3. The summarize handler omitted platformSource from the
   /api/sessions/summarize request body, causing sessions to be recorded
   without the gemini-cli source tag.

Co-authored-by: Claude <noreply@anthropic.com>

src/cli/adapters/gemini-cli.ts

@@ -13,7 +13,7 @@ import type { PlatformAdapter } from '../types.js';
  *   Notification  → observation (system events like ToolPermission)
  *
  * Agent:
- *   BeforeAgent   → user-message (captures user prompt)
+ *   BeforeAgent   → session-init (initializes session, captures user prompt)
  *   AfterAgent    → observation  (full agent response)
  *
  * Tool:

src/cli/handlers/summarize.ts

@@ -18,6 +18,7 @@ import { ensureWorkerRunning, workerHttpRequest } from '../../shared/worker-util
 import { logger } from '../../utils/logger.js';
 import { extractLastMessage } from '../../shared/transcript-parser.js';
 import { HOOK_EXIT_CODES, HOOK_TIMEOUTS, getTimeout } from '../../shared/hook-constants.js';
+import { normalizePlatformSource } from '../../shared/platform-source.js';
 
 const SUMMARIZE_TIMEOUT_MS = getTimeout(HOOK_TIMEOUTS.DEFAULT);
 const POLL_INTERVAL_MS = 500;
@@ -66,13 +67,16 @@ export const summarizeHandler: EventHandler = {
       hasLastAssistantMessage: !!lastAssistantMessage
     });
 
+    const platformSource = normalizePlatformSource(input.platform);
+
     // 1. Queue summarize request — worker returns immediately with { status: 'queued' }
     const response = await workerHttpRequest('/api/sessions/summarize', {
       method: 'POST',
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify({
         contentSessionId: sessionId,
-        last_assistant_message: lastAssistantMessage
+        last_assistant_message: lastAssistantMessage,
+        platformSource
       }),
       timeoutMs: SUMMARIZE_TIMEOUT_MS
     });

src/services/integrations/GeminiCliHooksInstaller.ts

@@ -80,7 +80,7 @@ const HOOK_TIMEOUT_MS = 10000;
  */
 const GEMINI_EVENT_TO_INTERNAL_EVENT: Record<string, string> = {
   'SessionStart': 'context',
-  'BeforeAgent': 'user-message',
+  'BeforeAgent': 'session-init',
   'AfterAgent': 'observation',
   'BeforeTool': 'observation',
   'AfterTool': 'observation',

src/shared/transcript-parser.ts

@@ -3,7 +3,37 @@ import { logger } from '../utils/logger.js';
 import { SYSTEM_REMINDER_REGEX } from '../utils/tag-stripping.js';
 
 /**
- * Extract last message of specified role from transcript JSONL file
+ * Detect whether a transcript file is in Gemini CLI JSON document format.
+ *
+ * Gemini CLI 0.37.0 writes a single JSON document with a top-level `messages`
+ * array instead of JSONL. Assistant entries use `type: "gemini"` rather than
+ * `type: "assistant"`.
+ *
+ * Example Gemini format:
+ *   { "messages": [{ "type": "user", "content": "..." }, { "type": "gemini", "content": "..." }] }
+ *
+ * Claude Code format (JSONL):
+ *   {"type":"assistant","message":{"content":[{"type":"text","text":"..."}]}}
+ */
+function isGeminiTranscriptFormat(content: string): { isGemini: true; messages: any[] } | { isGemini: false } {
+  try {
+    const parsed = JSON.parse(content);
+    if (parsed && Array.isArray(parsed.messages)) {
+      return { isGemini: true, messages: parsed.messages };
+    }
+  } catch {
+    // Not a valid single JSON object — assume JSONL
+  }
+  return { isGemini: false };
+}
+
+/**
+ * Extract last message of specified role from transcript file.
+ *
+ * Supports two transcript formats:
+ * - JSONL (Claude Code): one JSON object per line, `type: "assistant"` or `type: "user"`
+ * - JSON document (Gemini CLI 0.37.0+): `{ messages: [{ type: "gemini"|"user", content: string }] }`
+ *
  * @param transcriptPath Path to transcript file
  * @param role 'user' or 'assistant'
  * @param stripSystemReminders Whether to remove <system-reminder> tags (for assistant)
@@ -24,6 +54,52 @@ export function extractLastMessage(
     return '';
   }
 
+  // Gemini CLI 0.37.0 writes a JSON document rather than JSONL.
+  // Detect and handle it before falling through to the JSONL parser.
+  const geminiCheck = isGeminiTranscriptFormat(content);
+  if (geminiCheck.isGemini) {
+    return extractLastMessageFromGeminiTranscript(geminiCheck.messages, role, stripSystemReminders);
+  }
+
+  return extractLastMessageFromJsonl(content, role, stripSystemReminders);
+}
+
+/**
+ * Extract last message from Gemini CLI JSON document transcript.
+ * Maps `type: "gemini"` → assistant role; `type: "user"` → user role.
+ */
+function extractLastMessageFromGeminiTranscript(
+  messages: any[],
+  role: 'user' | 'assistant',
+  stripSystemReminders: boolean
+): string {
+  // "gemini" entries are assistant turns; "user" entries are user turns
+  const geminiRole = role === 'assistant' ? 'gemini' : 'user';
+
+  for (let i = messages.length - 1; i >= 0; i--) {
+    const msg = messages[i];
+    if (msg?.type === geminiRole && typeof msg.content === 'string') {
+      let text = msg.content;
+      if (stripSystemReminders) {
+        text = text.replace(SYSTEM_REMINDER_REGEX, '');
+        text = text.replace(/\n{3,}/g, '\n\n').trim();
+      }
+      return text;
+    }
+  }
+
+  return '';
+}
+
+/**
+ * Extract last message from Claude Code JSONL transcript.
+ * Each line is an independent JSON object with `type: "assistant"` or `type: "user"`.
+ */
+function extractLastMessageFromJsonl(
+  content: string,
+  role: 'user' | 'assistant',
+  stripSystemReminders: boolean
+): string {
   const lines = content.split('\n');
   let foundMatchingRole = false;