reset message ids after /compact

Clear DCP message alias state when native compaction is detected so refs rebuild from the compacted conversation instead of continuing toward m9999.

Author: Tarquinen

lib/state/utils.ts

@@ -280,6 +280,11 @@ export function resetOnCompaction(state: SessionState): void {
     state.toolParameters.clear()
     state.prune.tools = new Map<string, number>()
     state.prune.messages = createPruneMessagesState()
+    state.messageIds = {
+        byRawId: new Map<string, string>(),
+        byRef: new Map<string, string>(),
+        nextRef: 1,
+    }
     state.nudges = {
         contextLimitAnchors: new Set<string>(),
         turnNudgeAnchors: new Set<string>(),

tests/message-ids.test.ts

@@ -0,0 +1,89 @@
+import assert from "node:assert/strict"
+import test from "node:test"
+import { Logger } from "../lib/logger"
+import { assignMessageRefs } from "../lib/message-ids"
+import { checkSession, createSessionState, type WithParts } from "../lib/state"
+
+function textPart(messageID: string, sessionID: string, id: string, text: string) {
+    return {
+        id,
+        messageID,
+        sessionID,
+        type: "text" as const,
+        text,
+    }
+}
+
+function buildCompactedMessages(sessionID: string): WithParts[] {
+    return [
+        {
+            info: {
+                id: "msg-assistant-summary",
+                role: "assistant",
+                sessionID,
+                agent: "assistant",
+                summary: true,
+                time: { created: 2 },
+            } as WithParts["info"],
+            parts: [
+                textPart(
+                    "msg-assistant-summary",
+                    sessionID,
+                    "msg-assistant-summary-part",
+                    "Compaction summary",
+                ),
+            ],
+        },
+        {
+            info: {
+                id: "msg-user-follow-up",
+                role: "user",
+                sessionID,
+                agent: "assistant",
+                model: {
+                    providerID: "anthropic",
+                    modelID: "claude-test",
+                },
+                time: { created: 3 },
+            } as WithParts["info"],
+            parts: [
+                textPart(
+                    "msg-user-follow-up",
+                    sessionID,
+                    "msg-user-follow-up-part",
+                    "Continue after compaction",
+                ),
+            ],
+        },
+    ]
+}
+
+test("checkSession resets message id aliases after native compaction", async () => {
+    const sessionID = `ses_message_ids_after_compaction_${Date.now()}`
+    const messages = buildCompactedMessages(sessionID)
+    const state = createSessionState()
+    const logger = new Logger(false)
+
+    state.sessionId = sessionID
+    state.messageIds.byRawId.set("old-message-9998", "m9998")
+    state.messageIds.byRawId.set("old-message-9999", "m9999")
+    state.messageIds.byRef.set("m9998", "old-message-9998")
+    state.messageIds.byRef.set("m9999", "old-message-9999")
+    state.messageIds.nextRef = 9999
+
+    await checkSession({} as any, state, logger, messages, false)
+
+    assert.equal(state.lastCompaction, 2)
+    assert.equal(state.messageIds.byRawId.size, 0)
+    assert.equal(state.messageIds.byRef.size, 0)
+    assert.equal(state.messageIds.nextRef, 1)
+
+    const assigned = assignMessageRefs(state, messages)
+
+    assert.equal(assigned, 2)
+    assert.equal(state.messageIds.byRawId.get("msg-assistant-summary"), "m0001")
+    assert.equal(state.messageIds.byRawId.get("msg-user-follow-up"), "m0002")
+    assert.equal(state.messageIds.byRef.get("m0001"), "msg-assistant-summary")
+    assert.equal(state.messageIds.byRef.get("m0002"), "msg-user-follow-up")
+    assert.equal(state.messageIds.nextRef, 3)
+})