feat(session-historian): cross-platform session history agent and /ce-sessions skill (#534)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/fixtures/session-history/claude-session.jsonl

@@ -0,0 +1,10 @@
+{"parentUuid":null,"type":"user","message":{"role":"user","content":"fix the auth bug"},"uuid":"aaa","timestamp":"2026-04-05T10:00:00.000Z","gitBranch":"feat/auth-fix","sessionId":"test-claude-session-1","cwd":"/Users/test/Code/my-repo"}
+{"type":"assistant","message":{"role":"assistant","content":[{"type":"text","text":"I'll investigate the auth module."},{"type":"tool_use","name":"Read","input":{"file_path":"/Users/test/Code/my-repo/src/auth.ts"}}]},"timestamp":"2026-04-05T10:00:05.000Z"}
+{"type":"user","message":{"role":"user","content":[{"type":"tool_result","tool_use_id":"t1","is_error":false,"content":"file contents here"}]},"timestamp":"2026-04-05T10:00:06.000Z"}
+{"type":"assistant","message":{"role":"assistant","content":[{"type":"text","text":"Found the issue. The token validation is missing."},{"type":"tool_use","name":"Edit","input":{"file_path":"/Users/test/Code/my-repo/src/auth.ts","old_string":"validate()","new_string":"validateToken()"}}]},"timestamp":"2026-04-05T10:00:10.000Z"}
+{"type":"user","message":{"role":"user","content":[{"type":"tool_result","tool_use_id":"t2","is_error":true,"content":"Error: String to replace not found in file"}]},"timestamp":"2026-04-05T10:00:11.000Z"}
+{"type":"user","message":{"role":"user","content":"no, that's not the right approach. check the middleware instead"},"timestamp":"2026-04-05T10:00:15.000Z"}
+{"type":"assistant","message":{"role":"assistant","content":[{"type":"text","text":"<local-command-stdout>Server restarted</local-command-stdout>"}]},"timestamp":"2026-04-05T10:00:16.000Z"}
+{"type":"user","message":{"role":"user","content":"<task-notification><task-id>abc123</task-id><tool-use-id>t3</tool-use-id><status>completed</status></task-notification>"},"timestamp":"2026-04-05T10:00:20.000Z"}
+{"type":"user","message":{"role":"user","content":"<local-command-caveat>Caveat: The messages below were generated by the user while running local commands.</local-command-caveat>"},"timestamp":"2026-04-05T10:00:21.000Z"}
+{"type":"assistant","message":{"role":"assistant","content":[{"type":"text","text":"The middleware fix is applied and working."}]},"timestamp":"2026-04-05T10:05:00.000Z"}

tests/fixtures/session-history/codex-session.jsonl

@@ -0,0 +1,10 @@
+{"timestamp":"2026-04-06T14:00:00.000Z","type":"session_meta","payload":{"id":"test-codex-session-1","timestamp":"2026-04-06T14:00:00.000Z","cwd":"/Users/test/Code/my-repo","originator":"codex_sdk_ts","cli_version":"0.107.0","source":"vscode","model_provider":"openai"}}
+{"timestamp":"2026-04-06T14:00:01.000Z","type":"turn_context","payload":{"turn_id":"turn-1","cwd":"/Users/test/Code/my-repo","model":"gpt-5.4"}}
+{"timestamp":"2026-04-06T14:00:02.000Z","type":"event_msg","payload":{"type":"user_message","message":"<system_instruction>You are working inside Conductor.</system_instruction>\n\nFix the auth bug in middleware"}}
+{"timestamp":"2026-04-06T14:00:05.000Z","type":"response_item","payload":{"type":"message","role":"assistant","content":[{"type":"output_text","text":"Reading the middleware file to understand the auth flow."}]}}
+{"timestamp":"2026-04-06T14:00:05.000Z","type":"response_item","payload":{"type":"function_call","name":"exec_command","arguments":"{\"cmd\":\"sed -n '1,50p' src/middleware/auth.ts\",\"workdir\":\"/Users/test/Code/my-repo\"}"}}
+{"timestamp":"2026-04-06T14:00:06.000Z","type":"event_msg","payload":{"type":"exec_command_end","call_id":"c1","command":["/bin/zsh","-lc","sed -n '1,50p' src/middleware/auth.ts"],"cwd":"/Users/test/Code/my-repo","aggregated_output":"Chunk ID: abc\nWall time: 0.05 seconds\nProcess exited with code 0\nOutput:\nexport function authMiddleware() {"}}
+{"timestamp":"2026-04-06T14:00:07.000Z","type":"response_item","payload":{"type":"function_call","name":"exec_command","arguments":"{\"cmd\":\"sed -n '1,50p' src/middleware/session.ts\"}"}}
+{"timestamp":"2026-04-06T14:00:08.000Z","type":"event_msg","payload":{"type":"exec_command_end","call_id":"c2","command":["/bin/zsh","-lc","sed -n '1,50p' src/middleware/session.ts"],"cwd":"/Users/test/Code/my-repo","aggregated_output":"Chunk ID: def\nWall time: 0.05 seconds\nProcess exited with code 1\nOutput:\ncat: src/middleware/session.ts: No such file or directory"}}
+{"timestamp":"2026-04-06T14:00:10.000Z","type":"response_item","payload":{"type":"message","role":"assistant","content":[{"type":"output_text","text":"The session middleware doesn't exist. The auth is handled entirely in auth.ts."}]}}
+{"timestamp":"2026-04-06T14:00:30.000Z","type":"event_msg","payload":{"type":"task_complete","turn_id":"turn-1"}}

tests/fixtures/session-history/cursor-session.jsonl

@@ -0,0 +1,6 @@
+{"role":"user","message":{"content":[{"type":"text","text":"<user_query>\nExplain the auth middleware\n</user_query>"}]}}
+{"role":"assistant","message":{"content":[{"type":"text","text":"[REDACTED]"},{"type":"tool_use","name":"Read","input":{"path":"/Users/test/Code/my-repo/src/auth.ts"}},{"type":"tool_use","name":"Grep","input":{"pattern":"middleware","path":"/Users/test/Code/my-repo/src"}}]}}
+{"role":"assistant","message":{"content":[{"type":"text","text":"The auth middleware validates JWT tokens on every request. It checks the Authorization header and verifies the token signature against the public key."}]}}
+{"role":"user","message":{"content":[{"type":"text","text":"<user_query>\nwhy was it built this way\n</user_query>"}]}}
+{"role":"assistant","message":{"content":[{"type":"text","text":"[REDACTED]"},{"type":"tool_use","name":"Read","input":{"path":"/Users/test/Code/my-repo/docs/auth-design.md"}}]}}
+{"role":"assistant","message":{"content":[{"type":"text","text":"It was built this way because the team wanted stateless auth that doesn't require a session store. JWT tokens are self-contained and can be verified without a database lookup."}]}}