Summary

Feishu group messages (and any channel with per-turn metadata injection) can trigger cli session reset: reason=system-prompt on every consecutive turn. This happens because per-turn volatile context flows through extraSystemPromptHash — the same value used for CLI session reuse identity. When the identity hash changes on every turn, the agent spawns a fresh Claude/tmux process instead of resuming the existing conversation. In active group chats, this leads to amnesia between consecutive turns and, more critically, to A-type empty output failures (transcriptEmitted=false, chars=0, bufferedPaneFlushed=true).

Root cause

src/auto-reply/reply/get-reply-run.ts assembles extraSystemPromptParts containing:

• inboundMetaPrompt — DYNAMIC: timestamp, message_id, sender info (changes every turn)
• groupChatContext — DYNAMIC: recent member activity, chat history (changes every turn)
• groupIntro — DYNAMIC: present only on turn 1, absent on subsequent turns
• groupSystemPrompt — STABLE: admin-configured group system prompt

This entire block gets concatenated into extraSystemPrompt and passed to prepareCliRunContext (src/agents/cli-runner/prepare.ts), which hashes it as:

const extraSystemPromptHash = hashCliSessionText(extraSystemPrompt);

resolveCliSessionReuse then compares stored vs current hash and returns invalidatedReason: 'system-prompt' whenever any dynamic part changes — which is every turn.

Three required fixes

1. Hash layering (primary)

Turn context must NOT participate in CLI session identity. The hash should cover only stable parts (e.g., groupSystemPrompt). Add a stableExtraSystemPrompt field to RunCliAgentParams so the hash input is decoupled from the full prompt that gets delivered to Claude.

Dynamic content that must NOT invalidate reuse:

• recent_group_context
• Inbound metadata / message id
• Thread history / thread starter body
• Group chat recent history / groupChatContext
• groupIntro (turn-1 vs turn-2+ difference)

Changes that MUST still invalidate reuse:

• Stable system prompt changes
• Auth profile / auth epoch rotation
• MCP config changes

2. Tmux clean boundary

When a fresh/retry is genuinely required, two Claude processes must not consume the same prompt. After healViaResume, the transcript state (transcript, transcriptEmitted, cliSessionId) must be reset so stale pane/transcript residue cannot contaminate the current run's output.

3. Empty output fail-closed

If a run ends with transcriptEmitted=false && chars=0 (no transcript emitted and no usable pane fallback), the system must NOT silently deliver an empty message. It must:

1. Retry once with a clean fresh boundary
2. If retry also fails, return an explicit error with diagnostic fields: runId, sessionName, launchMode, reason, transcriptPath, paneTailSize, retryAttempt

Acceptance Criteria

1. Group message changes no longer trigger cli session reset: reason=system-prompt
2. recent_group_context / groupChatContext changes do not change the CLI session reuse hash
3. groupIntro presence/absence (turn 1 vs 2+) does not change the reuse hash
4. Stable groupSystemPrompt changes still change the stable hash and invalidate when appropriate
5. Auth profile / auth epoch / MCP content changes still invalidate reuse
6. Consecutive group turns in the same session reuse the same CLI/tmux session
7. If an old pane has envelope residue and transcript is missing, the system does not emit an empty message; it retries or returns an explicit error
8. Empty-output diagnostics include runId/sessionName/launchMode/reason/transcriptPath/paneTailSize/retryAttempt

Related issues

• Claude CLI sessions reset on every turn in group channels due to groupIntro drift in extraSystemPromptHash #69118 — covers extraSystemPromptHash invalidation via groupIntro drift
• [Bug]: systemPromptHash in buildClaudeLiveFingerprint causes phantom claude-cli session restarts on every turn for chat channels #81041 — covers systemPromptHash in buildClaudeLiveFingerprint for chat channels

Minimum tests

• Unit: changing recent_group_context / groupChatContext / dynamic turn context does not change reuse identity hash
• Unit: changing groupSystemPrompt (stable) does change the stable hash
• Regression: old pane has envelope residue + transcript missing → no empty output delivered; system retries or fails explicitly