fix: validate and compact session entries

src/main/agent-runtime/sqlite-session-store.ts

@@ -1,15 +1,22 @@
 import type { AgentMessage } from "@mariozechner/pi-agent-core";
 import type { AppDatabase } from "@main/database";
+import { compactMessagesIfNeeded } from "./context-compactor";
+import {
+  decodeAgentMessageFromSessionEntry,
+  encodeAgentMessageForSession,
+  getAgentMessageRole,
+  validateNewAgentMessageForSession,
+} from "./agent-message-schema";
 
 /**
  * SQLite-backed pi `AgentMessage[]` store.
  *
  * One store instance per task_session. `appendMessage` runs exactly
  * once per pi `message_end` event; `loadMessages` reads the live
- * transcript back at `prepareRun`. Compaction happens at LLM-call
- * time via pi's `transformContext` hook and does not rewrite the
- * persisted transcript — the session shadow is the durable truth,
- * the compacted payload is a per-call view.
+ * transcript back at `prepareRun`. When the persisted transcript
+ * crosses the compaction threshold, `loadMessages` writes a durable
+ * summary row and supersedes the older rows inside one DB transaction,
+ * leaving the recent tail as the active transcript.
  */
 export class SqliteSessionStore {
   constructor(
@@ -19,21 +26,37 @@ export class SqliteSessionStore {
 
   loadMessages(): AgentMessage[] {
     const rows = this.db.projection.sessionEntries.listActive(this.taskSessionId);
-    const result: AgentMessage[] = [];
+    const messages: AgentMessage[] = [];
     for (const row of rows) {
       if (row.kind === "message") {
-        result.push(JSON.parse(row.payloadJson) as AgentMessage);
+        messages.push(decodeAgentMessageFromSessionEntry(row));
       }
     }
-    return result;
+    const outcome = compactMessagesIfNeeded(messages);
+    if (!outcome.changed || !outcome.messages || !outcome.telemetry) {
+      return messages;
+    }
+    const summary = outcome.messages[0];
+    if (!summary) {
+      return messages;
+    }
+    const olderRows = rows.slice(0, outcome.telemetry.compactedOlderMessageCount);
+    this.db.projection.sessionEntries.compactWithSummary({
+      taskSessionId: this.taskSessionId,
+      supersedeEntryIds: olderRows.map((row) => row.id),
+      summaryRole: getAgentMessageRole(summary),
+      summaryPayloadJson: encodeAgentMessageForSession(summary),
+    });
+    return outcome.messages;
   }
 
   appendMessage(message: AgentMessage): void {
+    const normalized = validateNewAgentMessageForSession(message);
     this.db.projection.sessionEntries.append({
       taskSessionId: this.taskSessionId,
       kind: "message",
-      role: (message as { role?: string }).role ?? null,
-      payloadJson: JSON.stringify(message),
+      role: getAgentMessageRole(normalized),
+      payloadJson: encodeAgentMessageForSession(normalized),
     });
   }
 }