fix(paired): bound arbiter interventions to stop infinite arbiter loop

The owner↔reviewer↔arbiter loop could repeat forever: when the arbiter
ruled PROCEED/REVISE/RESET it reset round_trip_count to 0, and nothing
tracked how many times the arbiter had already intervened. A re-deadlock
re-invoked the arbiter without bound.

Add a persistent arbiter_intervention_count (new column + migration 020)
that survives the round-trip reset, and a configurable cap
ARBITER_MAX_INTERVENTIONS (default 1). Once the arbiter has intervened
that many times and the loop still deadlocks, requestArbiterOrEscalate
escalates straight to the user instead of re-invoking the arbiter.

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

src/db/base-schema.ts

@@ -147,6 +147,7 @@ export function applyBaseSchema(database: Database): void {
       finalize_step_done_count INTEGER NOT NULL DEFAULT 0,
       task_done_then_user_reopen_count INTEGER NOT NULL DEFAULT 0,
       empty_step_done_streak INTEGER NOT NULL DEFAULT 0,
+      arbiter_intervention_count INTEGER NOT NULL DEFAULT 0,
       status TEXT NOT NULL DEFAULT 'active',
       arbiter_verdict TEXT,
       arbiter_requested_at TEXT,

src/db/migrations/020_arbiter-intervention-count.ts

@@ -0,0 +1,25 @@
+import type { Database } from 'bun:sqlite';
+
+import { tableHasColumn } from './helpers.js';
+import type { SchemaMigrationDefinition } from './types.js';
+
+export const ARBITER_INTERVENTION_COUNT_MIGRATION: SchemaMigrationDefinition = {
+  version: 20,
+  name: 'arbiter_intervention_count',
+  apply(database: Database) {
+    if (
+      !tableHasColumn(database, 'paired_tasks', 'arbiter_intervention_count')
+    ) {
+      database.exec(`
+        ALTER TABLE paired_tasks
+        ADD COLUMN arbiter_intervention_count INTEGER NOT NULL DEFAULT 0
+      `);
+    }
+
+    database.exec(`
+      UPDATE paired_tasks
+         SET arbiter_intervention_count = 0
+       WHERE arbiter_intervention_count IS NULL
+    `);
+  },
+};

src/db/migrations/index.ts

@@ -19,6 +19,7 @@ import { ROOM_SKILL_OVERRIDES_MIGRATION } from './016_room-skill-overrides.js';
 import { SCHEDULED_TASK_ROOM_ROLE_MIGRATION } from './017_scheduled-task-room-role.js';
 import { PAIRED_TURN_OUTPUT_ATTACHMENTS_MIGRATION } from './018_paired-turn-output-attachments.js';
 import { TURN_PROGRESS_TEXT_RECOVERY_MIGRATION } from './019_turn-progress-text-recovery.js';
+import { ARBITER_INTERVENTION_COUNT_MIGRATION } from './020_arbiter-intervention-count.js';
 import type {
   SchemaMigrationArgs,
   SchemaMigrationDefinition,
@@ -46,6 +47,7 @@ const ORDERED_SCHEMA_MIGRATIONS: readonly SchemaMigrationDefinition[] = [
   SCHEDULED_TASK_ROOM_ROLE_MIGRATION,
   PAIRED_TURN_OUTPUT_ATTACHMENTS_MIGRATION,
   TURN_PROGRESS_TEXT_RECOVERY_MIGRATION,
+  ARBITER_INTERVENTION_COUNT_MIGRATION,
 ];
 
 function ensureSchemaMigrationsTable(database: Database): void {

src/db/paired-state.ts

@@ -54,6 +54,7 @@ export type PairedTaskUpdates = Partial<
     | 'finalize_step_done_count'
     | 'task_done_then_user_reopen_count'
     | 'empty_step_done_streak'
+    | 'arbiter_intervention_count'
     | 'status'
     | 'arbiter_verdict'
     | 'arbiter_requested_at'
@@ -180,6 +181,7 @@ export function createPairedTaskInDatabase(
           finalize_step_done_count,
           task_done_then_user_reopen_count,
           empty_step_done_streak,
+          arbiter_intervention_count,
           status,
           arbiter_verdict,
           arbiter_requested_at,
@@ -187,7 +189,7 @@ export function createPairedTaskInDatabase(
           created_at,
           updated_at
         )
-        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
       `,
     )
     .run(
@@ -209,6 +211,7 @@ export function createPairedTaskInDatabase(
       task.finalize_step_done_count ?? 0,
       task.task_done_then_user_reopen_count ?? 0,
       task.empty_step_done_streak ?? 0,
+      task.arbiter_intervention_count ?? 0,
       task.status,
       task.arbiter_verdict,
       task.arbiter_requested_at,
@@ -355,6 +358,10 @@ export function updatePairedTaskInDatabase(
     fields.push('empty_step_done_streak = ?');
     values.push(updates.empty_step_done_streak);
   }
+  if (updates.arbiter_intervention_count !== undefined) {
+    fields.push('arbiter_intervention_count = ?');
+    values.push(updates.arbiter_intervention_count);
+  }
   if (updates.status !== undefined) {
     fields.push('status = ?');
     values.push(updates.status);
@@ -434,6 +441,10 @@ export function updatePairedTaskIfUnchangedInDatabase(
     fields.push('empty_step_done_streak = ?');
     values.push(updates.empty_step_done_streak);
   }
+  if (updates.arbiter_intervention_count !== undefined) {
+    fields.push('arbiter_intervention_count = ?');
+    values.push(updates.arbiter_intervention_count);
+  }
   if (updates.status !== undefined) {
     fields.push('status = ?');
     values.push(updates.status);