diff --git a/src/paths.ts b/src/paths.ts
index f9433a4..1d11c29 100644
--- a/src/paths.ts
+++ b/src/paths.ts
@@ -20,6 +20,10 @@ export async function workspaceMemoryPath(root: string): Promise<string> {
   return join(await memoryRoot(root), "workspace-memory.json");
 }
 
+export async function workspacePendingJournalPath(root: string): Promise<string> {
+  return join(await memoryRoot(root), "workspace-pending-journal.json");
+}
+
 export async function sessionStatePath(root: string, sessionID: string): Promise<string> {
   const safeSessionID = createHash("sha256").update(sessionID).digest("hex").slice(0, 32);
   return join(await memoryRoot(root), "sessions", `${safeSessionID}.json`);
diff --git a/src/pending-journal.ts b/src/pending-journal.ts
new file mode 100644
index 0000000..0c5e49a
--- /dev/null
+++ b/src/pending-journal.ts
@@ -0,0 +1,102 @@
+import type { LongTermMemoryEntry, PendingMemoryJournalStore } from "./types.ts";
+import { workspaceKey, workspacePendingJournalPath } from "./paths.ts";
+import { atomicWriteJSON, readJSON, updateJSON } from "./storage.ts";
+
+function normalizeMemoryText(text: string): string {
+  return text
+    .normalize("NFKC")
+    .toLowerCase()
+    .replace(/[\s\p{P}]+/gu, " ")
+    .trim();
+}
+
+export function memoryKey(entry: Pick<LongTermMemoryEntry, "type" | "text">): string {
+  return `${entry.type}:${normalizeMemoryText(entry.text)}`;
+}
+
+export async function emptyPendingJournal(root: string): Promise<PendingMemoryJournalStore> {
+  return {
+    version: 1,
+    workspace: { root, key: await workspaceKey(root) },
+    entries: [],
+    updatedAt: new Date().toISOString(),
+  };
+}
+
+function dedupeByText(entries: LongTermMemoryEntry[]): LongTermMemoryEntry[] {
+  const seen = new Set<string>();
+  const result: LongTermMemoryEntry[] = [];
+
+  for (const entry of entries) {
+    const key = memoryKey(entry);
+    if (seen.has(key)) continue;
+    seen.add(key);
+    result.push(entry);
+  }
+
+  return result;
+}
+
+function normalizeJournal(
+  root: string,
+  store: PendingMemoryJournalStore,
+): Promise<PendingMemoryJournalStore> {
+  return workspaceKey(root).then(key => ({
+    version: 1,
+    workspace: { root, key },
+    entries: dedupeByText(Array.isArray(store.entries) ? store.entries : []),
+    updatedAt: new Date().toISOString(),
+  }));
+}
+
+export async function loadPendingJournal(root: string): Promise<PendingMemoryJournalStore> {
+  const path = await workspacePendingJournalPath(root);
+  const fallback = await emptyPendingJournal(root);
+  const loaded = await readJSON(path, () => fallback) as Partial<PendingMemoryJournalStore>;
+  return normalizeJournal(root, {
+    version: loaded.version ?? 1,
+    workspace: loaded.workspace ?? fallback.workspace,
+    entries: Array.isArray(loaded.entries) ? loaded.entries : [],
+    updatedAt: loaded.updatedAt ?? fallback.updatedAt,
+  });
+}
+
+export async function savePendingJournal(root: string, store: PendingMemoryJournalStore): Promise<void> {
+  await atomicWriteJSON(await workspacePendingJournalPath(root), await normalizeJournal(root, store));
+}
+
+export async function updatePendingJournal(
+  root: string,
+  updater: (store: PendingMemoryJournalStore) => PendingMemoryJournalStore | Promise<PendingMemoryJournalStore>,
+): Promise<PendingMemoryJournalStore> {
+  const path = await workspacePendingJournalPath(root);
+  const fallback = await emptyPendingJournal(root);
+  return updateJSON(path, () => fallback, async current => {
+    const normalized = await normalizeJournal(root, current);
+    return normalizeJournal(root, await updater(normalized));
+  });
+}
+
+export async function appendPendingMemories(root: string, memories: LongTermMemoryEntry[]): Promise<void> {
+  if (memories.length === 0) return;
+  await updatePendingJournal(root, store => {
+    store.entries.push(...memories);
+    return store;
+  });
+}
+
+export async function hasPendingJournalEntries(root: string): Promise<boolean> {
+  const journal = await loadPendingJournal(root);
+  return journal.entries.length > 0;
+}
+
+export async function clearPendingMemories(root: string, keys?: Set<string>): Promise<void> {
+  await updatePendingJournal(root, store => {
+    if (!keys || keys.size === 0) {
+      store.entries = [];
+      return store;
+    }
+    store.entries = store.entries.filter(entry => !keys.has(memoryKey(entry)));
+    return store;
+  });
+}
diff --git a/src/plugin.ts b/src/plugin.ts
index c822621..8ea2afb 100644
--- a/src/plugin.ts
+++ b/src/plugin.ts
@@ -28,6 +28,13 @@ import {
   updateWorkspaceMemory,
   renderWorkspaceMemory,
 } from "./workspace-memory.ts";
+import {
+  appendPendingMemories,
+  clearPendingMemories,
+  hasPendingJournalEntries,
+  loadPendingJournal,
+  memoryKey,
+} from "./pending-journal.ts";
 import {
   loadSessionState,
   updateSessionState,
@@ -178,19 +185,13 @@ export const MemoryV2Plugin: Plugin = async (input) => {
 
     const memories = extractExplicitMemories(latestMessage.text);
     const decisions = memories.filter(memory => memory.type === "decision");
-    let workspaceMemory: Awaited<ReturnType<typeof loadWorkspaceMemory>> | undefined;
 
     if (memories.length > 0) {
-      workspaceMemory = await updateWorkspaceMemory(directory, store => {
-        store.entries.push(...memories);
-        return store;
+      await updateSessionState(directory, sessionID, state => {
+        state.pendingMemories.push(...memories);
+        return state;
       });
-
-      // Update frozen cache
-      const cached = frozenWorkspaceMemoryCache.get(sessionID);
-      if (cached) {
-        cached.store = workspaceMemory;
-      }
+      await appendPendingMemories(directory, memories);
     }
 
     if (decisions.length > 0) {
@@ -210,6 +211,45 @@ export const MemoryV2Plugin: Plugin = async (input) => {
     processedUserMessages.set(sessionID, processedForSession);
   }
 
+  async function promotePendingMemories(sessionID?: string): Promise<void> {
+    const [journal, sessionState] = await Promise.all([
+      loadPendingJournal(directory),
+      sessionID ? loadSessionState(directory, sessionID) : Promise.resolve(undefined),
+    ]);
+
+    const pending = [
+      ...(sessionState?.pendingMemories ?? []),
+      ...journal.entries,
+    ];
+    if (pending.length === 0) return;
+
+    const promotedKeys = new Set<string>();
+    await updateWorkspaceMemory(directory, workspaceMemory => {
+      const existingKeys = new Set(workspaceMemory.entries.map(memory => memoryKey(memory)));
+
+      for (const memory of pending) {
+        const key = memoryKey(memory);
+        if (!existingKeys.has(key)) {
+          workspaceMemory.entries.push(memory);
+          existingKeys.add(key);
+        }
+        promotedKeys.add(key);
+      }
+
+      return workspaceMemory;
+    });
+
+    if (sessionID) {
+      await updateSessionState(directory, sessionID, state => {
+        state.pendingMemories = state.pendingMemories.filter(memory => !promotedKeys.has(memoryKey(memory)));
+        return state;
+      });
+      clearFrozenWorkspaceMemoryCache(sessionID);
+    }
+
+    await clearPendingMemories(directory, promotedKeys);
+  }
+
   function bashExitCode(hookOutput: unknown): number | undefined {
     const output = hookOutput as {
       exitCode?: unknown;
@@ -273,6 +313,13 @@ export const MemoryV2Plugin: Plugin = async (input) => {
       // Sub-agents are short-lived - skip memory system
       if (await isSubAgent(sessionID)) return;
 
+      // Before first snapshot in this session, promote durable pending memories from
+      // prior sessions. Keep this before processing latest user text so current-turn
+      // explicit memory remains pending (not immediately frozen into system[1]).
+      if (!frozenWorkspaceMemoryCache.has(sessionID) && await hasPendingJournalEntries(directory)) {
+        await promotePendingMemories();
+      }
+
       // Process explicit user memory even on no-tool turns.
       await processLatestUserMessage(sessionID);
 
@@ -419,25 +466,32 @@ export const MemoryV2Plugin: Plugin = async (input) => {
         // Sub-agents don't need post-compaction processing
         if (await isSubAgent(sessionID)) return;
 
-        // Parse latest compaction summary for memory candidates
+        // Parse latest compaction summary for memory candidates, stage them into
+        // durable pending journal, then promote pending memories.
         const summary = await latestCompactionSummary(client, sessionID);
-        if (summary) {
-          const candidates = parseWorkspaceMemoryCandidates(summary);
-          if (candidates.length > 0) {
-            await updateWorkspaceMemory(directory, workspaceMemory => {
-              workspaceMemory.entries.push(...candidates);
-              return workspaceMemory;
-            });
+        const candidates = summary ? parseWorkspaceMemoryCandidates(summary) : [];
+        if (candidates.length > 0) {
+          await appendPendingMemories(directory, candidates);
+        }
 
-            // Clear frozen cache so next session reloads with new memories
-            clearFrozenWorkspaceMemoryCache(sessionID);
-          }
+        try {
+          await promotePendingMemories(sessionID);
+        } catch {
+          // Keep pending memories in session/journal for retry on next event/session.
         }
       }
 
       if (event.type === "session.deleted") {
         const sessionID = (event.properties as { info?: { id?: string } })?.info?.id;
         if (sessionID) {
+          // Promote pending memories before deleting per-session state.
+          // If promotion fails, leave session state and journal intact.
+          try {
+            await promotePendingMemories(sessionID);
+          } catch {
+            return;
+          }
+
           // Clean up caches
           frozenWorkspaceMemoryCache.delete(sessionID);
           processedUserMessages.delete(sessionID);
diff --git a/src/session-state.ts b/src/session-state.ts
index db0614b..c168459 100644
--- a/src/session-state.ts
+++ b/src/session-state.ts
@@ -1,8 +1,9 @@
 import { relative } from "path";
 import { sessionStatePath } from "./paths.ts";
 import { atomicWriteJSON, readJSON, updateJSON } from "./storage.ts";
-import type { ActiveFile, OpenError, SessionDecision, SessionState } from "./types.ts";
+import type { ActiveFile, LongTermMemoryEntry, OpenError, SessionDecision, SessionState } from "./types.ts";
 import { HOT_STATE_LIMITS } from "./types.ts";
+import { memoryKey } from "./pending-journal.ts";
 
 const ACTION_WEIGHT: Record<ActiveFile["action"], number> = {
   edit: 50,
@@ -20,6 +21,7 @@ export function createEmptySessionState(sessionID: string): SessionState {
     activeFiles: [],
     openErrors: [],
     recentDecisions: [],
+    pendingMemories: [],
   };
 }
 
@@ -30,6 +32,7 @@ export async function loadSessionState(root: string, sessionID: string): Promise
   loaded.activeFiles = Array.isArray(loaded.activeFiles) ? loaded.activeFiles : [];
   loaded.openErrors = Array.isArray(loaded.openErrors) ? loaded.openErrors : [];
   loaded.recentDecisions = Array.isArray(loaded.recentDecisions) ? loaded.recentDecisions : [];
+  loaded.pendingMemories = Array.isArray(loaded.pendingMemories) ? loaded.pendingMemories : [];
   return loaded;
 }
 
@@ -48,6 +51,7 @@ export async function updateSessionState(
     current.activeFiles = Array.isArray(current.activeFiles) ? current.activeFiles : [];
     current.openErrors = Array.isArray(current.openErrors) ? current.openErrors : [];
     current.recentDecisions = Array.isArray(current.recentDecisions) ? current.recentDecisions : [];
+    current.pendingMemories = Array.isArray(current.pendingMemories) ? current.pendingMemories : [];
     return normalizeSessionState(await updater(current));
   });
 }
@@ -57,9 +61,23 @@ function normalizeSessionState(state: SessionState): SessionState {
   state.activeFiles = state.activeFiles.slice(0, HOT_STATE_LIMITS.maxActiveFilesStored);
   state.openErrors = state.openErrors.slice(0, HOT_STATE_LIMITS.maxOpenErrorsStored);
   state.recentDecisions = state.recentDecisions.slice(0, HOT_STATE_LIMITS.maxRecentDecisionsStored);
+  state.pendingMemories = dedupePendingMemories(Array.isArray(state.pendingMemories) ? state.pendingMemories : [])
+    .slice(-HOT_STATE_LIMITS.maxPendingMemoriesStored);
   return state;
 }
 
+function dedupePendingMemories(memories: LongTermMemoryEntry[]): LongTermMemoryEntry[] {
+  const seen = new Set<string>();
+  const deduped: LongTermMemoryEntry[] = [];
+  for (const memory of memories) {
+    const key = memoryKey(memory);
+    if (seen.has(key)) continue;
+    seen.add(key);
+    deduped.push(memory);
+  }
+  return deduped;
+}
+
 export function touchActiveFile(state: SessionState, filePath: string, action: ActiveFile["action"]): void {
   const now = Date.now();
   const existing = state.activeFiles.find(item => item.path === filePath);
@@ -177,8 +195,10 @@ export function renderHotSessionState(state: SessionState, workspaceRoot: string
     .sort((a, b) => b.lastSeen - a.lastSeen)
     .slice(0, HOT_STATE_LIMITS.maxOpenErrorsRendered);
   const decisions = state.recentDecisions.slice(-HOT_STATE_LIMITS.maxRecentDecisionsStored);
+  const pendingMemories = dedupePendingMemories(state.pendingMemories)
+    .slice(-HOT_STATE_LIMITS.maxPendingMemoriesRendered);
 
-  if (activeFiles.length === 0 && openErrors.length === 0 && decisions.length === 0) return "";
+  if (activeFiles.length === 0 && openErrors.length === 0 && decisions.length === 0 && pendingMemories.length === 0) return "";
 
   const lines: string[] = ["Hot session state (current session):"];
 
@@ -204,6 +224,13 @@ export function renderHotSessionState(state: SessionState, workspaceRoot: string
     }
   }
 
+  if (pendingMemories.length > 0) {
+    lines.push("pending_memories:");
+    for (const memory of pendingMemories) {
+      lines.push(`- [${memory.type}] ${memory.text}`);
+    }
+  }
+
   return lines.join("\n").slice(0, HOT_STATE_LIMITS.maxRenderedChars);
 }
 
diff --git a/src/types.ts b/src/types.ts
index 1a5e58d..efa170f 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -32,6 +32,16 @@ export type WorkspaceMemoryStore = {
   updatedAt: string;
 };
 
+export type PendingMemoryJournalStore = {
+  version: 1;
+  workspace: {
+    root: string;
+    key: string;
+  };
+  entries: LongTermMemoryEntry[];
+  updatedAt: string;
+};
+
 export type ActiveFile = {
   path: string;
   action: "read" | "grep" | "edit" | "write";
@@ -69,6 +79,7 @@ export type SessionState = {
   activeFiles: ActiveFile[];
   openErrors: OpenError[];
   recentDecisions: SessionDecision[];
+  pendingMemories: LongTermMemoryEntry[];
 };
 
 export const LONG_TERM_LIMITS = {
@@ -86,4 +97,6 @@ export const HOT_STATE_LIMITS = {
   maxOpenErrorsStored: 5,
   maxOpenErrorsRendered: 3,
   maxRecentDecisionsStored: 8,
+  maxPendingMemoriesStored: 12,
+  maxPendingMemoriesRendered: 6,
 } as const;
diff --git a/tests/plugin.test.ts b/tests/plugin.test.ts
index c1d55f2..a40ea9d 100644
--- a/tests/plugin.test.ts
+++ b/tests/plugin.test.ts
@@ -1,18 +1,39 @@
 import test from "node:test";
 import assert from "node:assert/strict";
-import { mkdtemp, rm } from "node:fs/promises";
+import { mkdir, mkdtemp, rm } from "node:fs/promises";
 import { tmpdir } from "node:os";
-import { join } from "node:path";
+import { dirname, join } from "node:path";
 import { MemoryV2Plugin } from "../src/plugin.ts";
 import { loadSessionState, saveSessionState } from "../src/session-state.ts";
 import { parseWorkspaceMemoryCandidates } from "../src/extractors.ts";
 import type { OpenError } from "../src/types.ts";
+import { workspaceMemoryPath, workspacePendingJournalPath } from "../src/paths.ts";
+import { loadPendingJournal, savePendingJournal } from "../src/pending-journal.ts";
 
 // Mock client for root session (not a sub-agent)
 function mockRootClient() {
   return {
     session: {
       get: async () => ({ data: { parentID: null } }),
+      messages: async () => ({ data: [] }),
+      todo: async () => ({ data: [] }),
+    },
+  };
+}
+
+function mockClientWithLatestUser(text: string, messageID: string) {
+  return {
+    session: {
+      get: async () => ({ data: { parentID: null } }),
+      messages: async () => ({
+        data: [
+          {
+            info: { role: "user", id: messageID },
+            parts: [{ type: "text", text }],
+          },
+        ],
+      }),
+      todo: async () => ({ data: [] }),
     },
   };
 }
@@ -27,6 +48,7 @@ function createSessionWithError(sessionID: string, error: OpenError) {
     activeFiles: [],
     openErrors: [error],
     recentDecisions: [],
+    pendingMemories: [],
   };
 }
 
@@ -379,3 +401,227 @@ test("chat system transform reuses frozen rendered workspace snapshot", async ()
     await rm(tmpDir, { recursive: true, force: true });
   }
 });
+
+test("no compaction: explicit memory is promoted on next session start from durable journal", async () => {
+  const tmpDir = await mkdtemp(join(tmpdir(), "memory-plugin-test-"));
+
+  try {
+    const firstClient = mockClientWithLatestUser("remember this: Prefer boring cache boundaries.", "msg-remember-1");
+    const firstPlugin = await MemoryV2Plugin({ directory: tmpDir, client: firstClient });
+
+    await (firstPlugin as Record<string, Function>)["experimental.chat.system.transform"](
+      { sessionID: "session-without-compaction", model: {} },
+      { system: ["base header"] },
+    );
+
+    const secondPlugin = await MemoryV2Plugin({ directory: tmpDir, client: mockRootClient() });
+    const output = { system: ["base header"] };
+
+    await (secondPlugin as Record<string, Function>)["experimental.chat.system.transform"](
+      { sessionID: "new-session", model: {} },
+      output,
+    );
+
+    const workspacePrompt = output.system.find((part: string) => part.startsWith("Workspace memory"));
+    assert.match(workspacePrompt ?? "", /Prefer boring cache boundaries/);
+  } finally {
+    await rm(tmpDir, { recursive: true, force: true });
+  }
+});
+
+test("session.deleted promotes pending memories before deleting session state", async () => {
+  const tmpDir = await mkdtemp(join(tmpdir(), "memory-plugin-test-"));
+
+  try {
+    const client = mockClientWithLatestUser("remember this: Promote pending memories before delete.", "msg-delete-1");
+    const plugin = await MemoryV2Plugin({ directory: tmpDir, client });
+
+    await (plugin as Record<string, Function>)["experimental.chat.system.transform"](
+      { sessionID: "delete-session", model: {} },
+      { system: ["base header"] },
+    );
+
+    await (plugin as Record<string, Function>)["event"]({
+      event: {
+        type: "session.deleted",
+        properties: { info: { id: "delete-session" } },
+      },
+    });
+
+    const nextPlugin = await MemoryV2Plugin({ directory: tmpDir, client: mockRootClient() });
+    const output = { system: ["base header"] };
+    await (nextPlugin as Record<string, Function>)["experimental.chat.system.transform"](
+      { sessionID: "after-delete-session", model: {} },
+      output,
+    );
+
+    const workspacePrompt = output.system.find((part: string) => part.startsWith("Workspace memory"));
+    assert.match(workspacePrompt ?? "", /Promote pending memories before delete/);
+  } finally {
+    await rm(tmpDir, { recursive: true, force: true });
+  }
+});
+
+test("duplicate explicit memories dedupe by normalized type and text, not generated id", async () => {
+  const tmpDir = await mkdtemp(join(tmpdir(), "memory-plugin-test-"));
+
+  try {
+    const pluginA = await MemoryV2Plugin({
+      directory: tmpDir,
+      client: mockClientWithLatestUser("remember this: Prefer stable cache boundaries.", "msg-a"),
+    });
+    await (pluginA as Record<string, Function>)["experimental.chat.system.transform"](
+      { sessionID: "dedupe-session", model: {} },
+      { system: ["base header"] },
+    );
+
+    const pluginB = await MemoryV2Plugin({
+      directory: tmpDir,
+      client: mockClientWithLatestUser("remember this: prefer   stable cache boundaries.", "msg-b"),
+    });
+    await (pluginB as Record<string, Function>)["experimental.chat.system.transform"](
+      { sessionID: "dedupe-session", model: {} },
+      { system: ["base header"] },
+    );
+
+    await (pluginB as Record<string, Function>)["event"]({
+      event: { type: "session.compacted", properties: { sessionID: "dedupe-session" } },
+    });
+
+    const output = { system: ["base header"] };
+    const pluginC = await MemoryV2Plugin({ directory: tmpDir, client: mockRootClient() });
+    await (pluginC as Record<string, Function>)["experimental.chat.system.transform"](
+      { sessionID: "dedupe-next", model: {} },
+      output,
+    );
+
+    const joined = output.system.join("\n");
+    assert.equal((joined.match(/stable cache boundaries/gi) ?? []).length, 1);
+  } finally {
+    await rm(tmpDir, { recursive: true, force: true });
+  }
+});
+
+test("session.compacted promotes pending memories to workspace memory and clears pending list", async () => {
+  const tmpDir = await mkdtemp(join(tmpdir(), "memory-plugin-test-"));
+
+  try {
+    const client = mockRootClient();
+    const plugin = await MemoryV2Plugin({ directory: tmpDir, client });
+
+    await saveSessionState(tmpDir, {
+      version: 1,
+      sessionID: "promote-session",
+      turn: 1,
+      updatedAt: new Date().toISOString(),
+      activeFiles: [],
+      openErrors: [],
+      recentDecisions: [],
+      pendingMemories: [{
+        id: "mem_pending_1",
+        type: "decision",
+        text: "Use frozen rendered snapshots for cache stability.",
+        source: "explicit",
+        confidence: 1,
+        status: "active",
+        createdAt: new Date().toISOString(),
+        updatedAt: new Date().toISOString(),
+      }],
+    });
+
+    await (plugin as Record<string, Function>)["event"]({
+      event: {
+        type: "session.compacted",
+        properties: { sessionID: "promote-session" },
+      },
+    });
+
+    const state = await loadSessionState(tmpDir, "promote-session");
+    assert.equal(state.pendingMemories.length, 0,
+      "pending memories should be cleared after promotion");
+
+    const after = { system: ["base header"] };
+    await (plugin as Record<string, Function>)["experimental.chat.system.transform"](
+      { sessionID: "new-session-after-promotion", model: {} },
+      after,
+    );
+
+    const workspacePrompt = after.system.find((part: string) => part.startsWith("Workspace memory"));
+    assert.match(workspacePrompt ?? "", /Use frozen rendered snapshots for cache stability/);
+  } finally {
+    await rm(tmpDir, { recursive: true, force: true });
+  }
+});
+
+test("promotion failure does not clear pending memories in session or journal", async () => {
+  const tmpDir = await mkdtemp(join(tmpdir(), "memory-plugin-test-"));
+
+  try {
+    const client = mockRootClient();
+    const plugin = await MemoryV2Plugin({ directory: tmpDir, client });
+
+    const now = new Date().toISOString();
+    await saveSessionState(tmpDir, {
+      version: 1,
+      sessionID: "failure-session",
+      turn: 0,
+      updatedAt: now,
+      activeFiles: [],
+      openErrors: [],
+      recentDecisions: [],
+      pendingMemories: [{
+        id: "mem_pending_failure",
+        type: "decision",
+        text: "Keep pending when promotion fails",
+        source: "explicit",
+        confidence: 1,
+        status: "active",
+        createdAt: now,
+        updatedAt: now,
+      }],
+    });
+
+    const journalPath = await workspacePendingJournalPath(tmpDir);
+    await mkdir(dirname(journalPath), { recursive: true });
+    const journal = await loadPendingJournal(tmpDir);
+    journal.entries = [{
+      id: "mem_pending_failure_journal",
+      type: "decision",
+      text: "Keep pending when promotion fails",
+      source: "explicit",
+      confidence: 1,
+      status: "active",
+      createdAt: now,
+      updatedAt: now,
+    }];
+    await savePendingJournal(tmpDir, journal);
+
+    const wmPath = await workspaceMemoryPath(tmpDir);
+    await rm(wmPath, { force: true }).catch(() => undefined);
+    await mkdir(wmPath, { recursive: true });
+
+    let didThrow = false;
+    try {
+      await (plugin as Record<string, Function>)["event"]({
+        event: {
+          type: "session.compacted",
+          properties: { sessionID: "failure-session" },
+        },
+      });
+    } catch {
+      didThrow = true;
+    }
+    assert.equal(didThrow, false,
+      "promotion failure should not throw from session.compacted handler");
+
+    const state = await loadSessionState(tmpDir, "failure-session");
+    assert.equal(state.pendingMemories.length, 1,
+      "session pending memories should remain when promotion fails");
+
+    const pendingAfter = await loadPendingJournal(tmpDir);
+    assert.equal(pendingAfter.entries.length, 1,
+      "journal pending memories should remain when promotion fails");
+  } finally {
+    await rm(tmpDir, { recursive: true, force: true });
+  }
+});