Make arbiter ESCALATE self-contained so the user decides from one message

The user should be able to choose from the last arbiter message alone, without
scrolling back through the owner↔reviewer conversation. Instruct the arbiter, on
ESCALATE, to restate the decision in one sentence and list the options as a
short numbered list with per-option consequences, including only the minimum
context needed. Prompt files are read per-turn, so this is live immediately.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

prompts/arbiter-paired-room.md

@@ -22,6 +22,11 @@ You have been summoned because the owner and reviewer reached a deadlock after m
   - The situation cannot be resolved without user input, regardless of technical agreement
   - The same NEEDS_CONTEXT or BLOCKED is repeated after a prior PROCEED — this means your PROCEED did not resolve the issue
 
+  When you ESCALATE, your message is the ONLY thing the user reads to make their choice — they will not scroll back through the owner↔reviewer conversation. So make it fully self-contained:
+  - Restate the actual decision the user must make, in one plain sentence.
+  - List the concrete options as a short numbered list (1., 2., …) with a one-line consequence for each, so the user can reply with just a number or a short phrase.
+  - Include only the minimum context needed to decide — do not assume the user remembers the prior discussion.
+
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