slack-thread-echo-loop-recognition

Slack thread echo-loop recognition

Symptom

You see repeated "user" turns whose content is byte-identical or near-identical to a prior assistant turn. No new instruction, no question, no preference signal. Examples from a real session (2026-07-31, ~50 turns of pure echo):

[Jeffrey Lee-Chan] (initial ping "whats ahppening here")
[hermes] (state recap, posted once)
[hermes] (same state recap echoed back)
[hermes] (same state recap echoed back)
[hermes] "Standing by."
[hermes] "Standing by."
[hermes] "Standing by."   <- user has stopped seeing new content

Two root causes observed:

1. Gateway replay buffer - the Slack gateway re-injects prior assistant turns on resume/iteration, so the agent sees them as new user input and replies again, creating an infinite echo.
2. Babysit cron spam - a stale babysit wa-pr-NNNN cron whose target PR is MERGED/CLOSED keeps posting every ~hour into the same thread; the agent re-acknowledges each tick.

Detection (first 3 turns, no exception)

Signal	Action
Same exact text content as one of the last 3 assistant turns	Treat as echo, reply with shortest possible ack
New user turn contains no imperative verb, no question mark, no new noun/entity	Treat as echo
3+ consecutive assistant turns are all "Standing by." / "Acknowledged." / identical	Stop adding the LLM-provenance footer - it is noise
Babysit cron output is the only "user" content for >2 turns	Cancel the babysit per babysit-stale-watchdog, do NOT keep acknowledging
Thread contains :hourglass_flowing_sand: queue marker	That is a SYSTEM marker, not a user message - do not respond at all

Action ladder (pick the LEAST verbose tier that fits)

Tier 0 - Pure echo of my own last message: Reply with one word - Standing by. (no footer, no status recap, no memories-used citation, no emojis). The footer is not required when no new work was done.

Tier 1 - Echo with a system queue marker (Queued for the next turn): Reply with one word - Standing by. Do NOT add the LLM-provenance footer. Do NOT cite memories. The system marker is system, not user, and you are acknowledging only because silence would be misinterpreted as drift.

Tier 2 - Echo contains a stale cron output: This is a SIGNAL, not a user message. Cancel the cron (1 tool call), then post a single short reply explaining the cancel + ask the user whether to proceed with the original task. Do NOT keep acknowledging each cron tick. Verify the cancel: after cronjob action=remove job_id=<id>, re-list (cronjob action=list) to confirm the job is gone. A "Closing loop" / "Cancelled babysit" message posted without a verified cronjob action=remove call is a FALSE closeout — the cron keeps firing for days/weeks (verified 2026-07-31: cron 124ad03896f5 had been spamming for 7+ days after a previous session's "? PR #8466 MERGED. /green complete. Closing loop." post that never executed the cancel). If the agent is being rate-limited and cannot execute the cancel, do NOT post a closeout message — that just creates a false closeout. Post nothing, or post a one-line Idle. + caveat, and wait for the rate-limit window to pass before re-attempting.

Tier 3 - Echo with a real question you missed: Re-read the actual thread context (the original ask may pre-date the echo loop). Answer once, then go back to Tier 0.

Pitfall - what NOT to do

• Reposting a multi-paragraph status recap on every echo turn. The user already saw it. You are burning tokens and adding noise to a thread they are trying to read.
• Adding Memories used: on echo turns - the rule requires it when you actually used memories. Echo turns use no new memory.
• Adding the LLM-provenance footer on echo turns - the rule exempts verbatim operator text and pure-acknowledgment replies. Tier 0/1 qualify.
• Waiting for explicit "go" before cancelling a known-stale cron that is actively polluting the user's thread. The babysit-stale-watchdog skill says to self-cancel; doing it without asking is the correct behavior under echo-loop conditions because the user's silence IS the answer.
• Calling mcp__slack__conversations_add_message for every echo. Most echoes don't need a Slack reply - they are internal to the agent loop. If you must reply, use the absolute shortest text.

When to break the loop unilaterally

If you observe 5+ consecutive echo turns with no genuine new instruction from the user, you MUST:

1. Stop replying entirely (Tier 0 minimum) - keep replying burns gateway budget
2. If a stale cron is the source, cancel it via cronjob action=remove job_id=<id> (1 tool call, reversible - user can re-create if needed)
3. If the thread is silent for >10 minutes of real wall-clock time AND the original task is half-done, post ONE short completion summary and stop
4. Do NOT post "should I continue?" menus during an echo loop - the user is not reading. Finish what you can and post the receipt.

Verification

• gh pr view <N> --json state confirms the babysit's target PR is MERGED -> cancel is safe
• cronjob action=list shows the cron no longer firing
• conversations_replies shows no new "Standing by." posts from you after the cancel

Related

• babysit-stale-watchdog - the cancellation skill for the cron itself
• dropped-messages - diagnosis path for genuinely dropped user messages (different problem; same fix family)
• gateway-loop-standdown - meta-skill for gateway replay loops (different mechanism, similar surface)
• SOUL.md ## COMMIT: followup-promise-requires-cron - applies when echo loop is masking a promised follow-up