Summarize a long ticket thread for handoff without losing the one detail that matters

You are summarizing a long support ticket thread so it can be handed off to another agent, team, or shift — the summary needs to let them act immediately without opening the full thread.

FULL TICKET THREAD
14-message thread over 5 days: customer reported a billing error, first agent asked for account details, second agent (after shift change) asked for the same details again, customer got frustrated, third agent identified the cause but had to leave shift before applying the fix.

WHY THIS IS BEING HANDED OFF
Shift change — outgoing agent identified the cause but the fix requires a permission level only the next shift's senior agent has.

WHAT THE NEXT AGENT NEEDS TO DECIDE OR DO
Apply the manual billing correction (already identified, just needs applying) and confirm the corrected amount with the customer.

ANY COMMITMENTS ALREADY MADE TO THE CUSTOMER
Second agent told the customer 'this will be resolved by end of day' — that deadline is today.

HOW TO SUMMARIZE
Do not write this as a chronological play-by-play of every message exchanged — write it backward from what the next agent needs to do, then include only the history that's relevant to that decision. State any commitment already made to the customer explicitly and prominently, even if it's just one line buried in message 6 of 14 — a promised refund, callback, or timeline that gets missed because it wasn't surfaced in the handoff is a broken promise the next agent didn't know they were making. Note the customer's current emotional state and how many times they've had to repeat themselves, if the thread shows escalating frustration — this changes how the next agent should open their reply. If something was tried and explicitly did not work, say so clearly so it isn't suggested again. Keep the summary itself short enough to read in under 30 seconds; anything that needs more context than that should be a link back to the specific message in the thread, not pasted in full.

WHAT NOT TO DO
Do not omit a commitment or promise made to the customer, even an informal one, for the sake of brevity — that's the one category of detail this summary must never drop. Do not editorialize about whether the customer's request is reasonable; state facts and status, not opinions about the case.

OUTPUT FORMAT
1. One-line status (where this stands right now).
2. Commitments already made to the customer (bulleted, even if just one).
3. What's already been tried and ruled out.
4. What the next agent needs to decide or do, per Apply the manual billing correction (already identified, just needs applying) and confirm the corrected amount with the customer..
5. Customer state note, if relevant (e.g., "third contact on this issue, growing frustrated").