feat(ultrawork): implement per-message model override with deferred DB retry strategy

- Add per-message ultrawork mode detection via keyword matching
- Implement deferred DB override strategy using microtask retry loop
- Fall back to setTimeout after 10 microtask retries for robustness
- Update agent configuration schema with ultrawork model/variant fields
- Integrate with chat.message hook to apply overrides on detection
- Add comprehensive tests for all override scenarios
- Generated schema includes ultrawork configuration

🤖 Generated with assistance of OhMyOpenCode (https://github.com/code-yeongyu/oh-my-opencode)

src/plugin/ultrawork-db-model-override.ts

@@ -0,0 +1,95 @@
+import { Database } from "bun:sqlite"
+import { join } from "node:path"
+import { existsSync } from "node:fs"
+import { getDataDir } from "../shared/data-path"
+import { log } from "../shared"
+
+function getDbPath(): string {
+  return join(getDataDir(), "opencode", "opencode.db")
+}
+
+const MAX_MICROTASK_RETRIES = 10
+
+function tryUpdateMessageModel(
+  db: InstanceType<typeof Database>,
+  messageId: string,
+  targetModel: { providerID: string; modelID: string },
+  variant?: string,
+): boolean {
+  const stmt = db.prepare(
+    `UPDATE message SET data = json_set(data, '$.model.providerID', ?, '$.model.modelID', ?) WHERE id = ?`,
+  )
+  const result = stmt.run(targetModel.providerID, targetModel.modelID, messageId)
+  if (result.changes === 0) return false
+
+  if (variant) {
+    db.prepare(
+      `UPDATE message SET data = json_set(data, '$.variant', ?, '$.thinking', ?) WHERE id = ?`,
+    ).run(variant, variant, messageId)
+  }
+  return true
+}
+
+function retryViaMicrotask(
+  db: InstanceType<typeof Database>,
+  messageId: string,
+  targetModel: { providerID: string; modelID: string },
+  variant: string | undefined,
+  attempt: number,
+): void {
+  if (attempt >= MAX_MICROTASK_RETRIES) {
+    log("[ultrawork-db-override] Exhausted microtask retries, falling back to setTimeout", {
+      messageId,
+      attempt,
+    })
+    setTimeout(() => {
+      if (tryUpdateMessageModel(db, messageId, targetModel, variant)) {
+        log(`[ultrawork-db-override] setTimeout fallback succeeded: ${targetModel.providerID}/${targetModel.modelID}`, { messageId })
+      } else {
+        log("[ultrawork-db-override] setTimeout fallback failed - message not found", { messageId })
+      }
+      db.close()
+    }, 0)
+    return
+  }
+
+  queueMicrotask(() => {
+    if (tryUpdateMessageModel(db, messageId, targetModel, variant)) {
+      log(`[ultrawork-db-override] Deferred DB update (attempt ${attempt}): ${targetModel.providerID}/${targetModel.modelID}`, { messageId })
+      db.close()
+      return
+    }
+    retryViaMicrotask(db, messageId, targetModel, variant, attempt + 1)
+  })
+}
+
+/**
+ * Schedules a deferred SQLite update to change the message model in the DB
+ * WITHOUT triggering a Bus event. Uses microtask retry loop to wait for
+ * Session.updateMessage() to save the message first, then overwrites the model.
+ *
+ * Falls back to setTimeout(fn, 0) after 10 microtask attempts.
+ */
+export function scheduleDeferredModelOverride(
+  messageId: string,
+  targetModel: { providerID: string; modelID: string },
+  variant?: string,
+): void {
+  queueMicrotask(() => {
+    const dbPath = getDbPath()
+    if (!existsSync(dbPath)) {
+      log("[ultrawork-db-override] DB not found, skipping deferred override")
+      return
+    }
+
+    const db = new Database(dbPath)
+    try {
+      retryViaMicrotask(db, messageId, targetModel, variant, 0)
+    } catch (error) {
+      log("[ultrawork-db-override] Failed to apply deferred model override", {
+        error: String(error),
+      })
+      db.close()
+    }
+  })
+}