diff --git a/src/session/assemble-runtime.ts b/src/session/assemble-runtime.ts
index abb223ed3..9998f8f61 100644
--- a/src/session/assemble-runtime.ts
+++ b/src/session/assemble-runtime.ts
@@ -556,6 +556,12 @@ export interface ChatAgentWiring {
    * side effects (stub notice, onFolded prune) run only after a fold lands.
    */
   getCompactor: (wrapPruning?: (pruning: Compactor) => Compactor) => Compactor;
+  /**
+   * Bound to the TUI compaction lifecycle abort signal. The completeness
+   * gate runs inside wrapCompactor's race, so a discarded certified stub
+   * must not persist a compaction-handoff for a fold that never landed.
+   */
+  isCompactionAborted?: () => boolean;
   /** Experimental Anthropic prompt shrink. Default off when omitted. */
   anthropicCachePrompt?: () => boolean;
   /**
@@ -786,7 +792,13 @@ export function assembleChatAgent(wiring: ChatAgentWiring): AssembledChatAgent {
           primaryArchive === undefined
             ? undefined
             : (pruning) =>
-                wrapCompactorWithCompletenessGate(pruning, primaryArchive),
+                wrapCompactorWithCompletenessGate(
+                  pruning,
+                  primaryArchive,
+                  wiring.isCompactionAborted === undefined
+                    ? undefined
+                    : { isAborted: wiring.isCompactionAborted },
+                ),
         ),
       },
     });
diff --git a/src/session/compaction-archive.ts b/src/session/compaction-archive.ts
index 00100d0ec..c00a58a2a 100644
--- a/src/session/compaction-archive.ts
+++ b/src/session/compaction-archive.ts
@@ -922,9 +922,12 @@ async function recordFreshHandoffOutput(
   archive: CompactionArchive,
   input: readonly ConversationTurn[],
   output: readonly ConversationTurn[],
+  isAborted?: () => boolean,
 ): Promise<void> {
+  if (isAborted?.() === true) return;
   const fresh = uncoveredContentUnits(output, input);
   for (const unit of fresh) {
+    if (isAborted?.() === true) return;
     if (unit.kind !== "text" || unit.role !== "user") continue;
     const text = unit.text ?? "";
     if (text.length === 0) continue;
@@ -946,11 +949,14 @@ async function recordFreshHandoffOutput(
  * Synthetic handoff spines (and pre-format fat summaries) are adopted into
  * the archive as user_message so a later fold may change the live spine.
  * After the fold certifies, the new spine is recorded so the next fold can
- * drop it even when the summarizer does not echo it verbatim.
+ * drop it even when the summarizer does not echo it verbatim. `isAborted`
+ * skips that record: the TUI wrapCompactor race can discard a certified
+ * stub, and a handoff for a fold that never landed is a phantom.
  */
 export function wrapCompactorWithCompletenessGate(
   inner: Compactor,
   archive: CompactionArchive,
+  opts?: { isAborted?: () => boolean },
 ): Compactor {
   return {
     name: inner.name,
@@ -982,7 +988,15 @@ export function wrapCompactorWithCompletenessGate(
       if (certificate.status !== "complete") {
         return incompleteIdentity(inner, turns);
       }
-      await recordFreshHandoffOutput(archive, turns, proposed.output);
+      if (opts?.isAborted?.() === true) {
+        return proposed;
+      }
+      await recordFreshHandoffOutput(
+        archive,
+        turns,
+        proposed.output,
+        opts?.isAborted,
+      );
       return proposed;
     },
   };
diff --git a/src/session/runtime-assembly.test.ts b/src/session/runtime-assembly.test.ts
index 3e6e0c682..c3eeb0942 100644
--- a/src/session/runtime-assembly.test.ts
+++ b/src/session/runtime-assembly.test.ts
@@ -37,6 +37,10 @@ import {
   createCompactionArchive,
   wrapCompactorWithCompletenessGate,
 } from "./compaction-archive.js";
+import {
+  COMPACTION_ABORTED_REASON,
+  createCompactionLifecycle,
+} from "./compaction-lifecycle.js";
 import { generateSessionId, initSessionDir, sessionDir } from "./index.js";
 import type { PluginModule } from "../plugins/loader.js";
 
@@ -876,6 +880,110 @@ describe("createSessionPruningCompactor stub fallback", () => {
     expect(notices).toHaveLength(1);
     expect(notices[0]).toContain("statistics-only stub");
     expect(notices[0]).toContain("failed");
+    const committedHandoffs = (await archive.listOccurrences()).filter(
+      (occurrence) => occurrence.provenance === "compaction-handoff",
+    );
+    expect(committedHandoffs.length).toBeGreaterThan(0);
+  });
+
+  test("TUI abort after a gate-committed stub does not record a phantom handoff", async () => {
+    const notices: string[] = [];
+    const folds: { stub: boolean }[] = [];
+    const summarize = createModelSummarizer({
+      getSource: () =>
+        ({
+          id: "test",
+          provider: "openai",
+          model: "test-model",
+          baseURL: "http://localhost:1",
+          credentialId: "test",
+        }) as never,
+      complete: async () => {
+        throw new Error("model unreachable");
+      },
+    });
+    const dir = await mkdtemp(join(tmpdir(), "compaction-gate-stub-abort-"));
+    const blobs = new Map<string, Uint8Array>();
+    const archive = createCompactionArchive({
+      sessionId: "sess-gate-stub-abort",
+      contextDir: dir,
+      writeBlob: async (key, bytes) => {
+        blobs.set(key, bytes);
+      },
+      readBlob: async (key) => {
+        const bytes = blobs.get(key);
+        if (bytes === undefined) throw new Error(`missing ${key}`);
+        return bytes;
+      },
+    });
+    const now = Date.now();
+    const many = Array.from({ length: 8 }, (_, i) => ({
+      role: (i % 2 === 0 ? "user" : "assistant") as "user" | "assistant",
+      content: [{ type: "text" as const, text: `t${i}` }],
+      timestamp: now,
+    }));
+    for (const turn of many) {
+      const block = turn.content[0];
+      if (block?.type !== "text") continue;
+      await archive.recordAuthorizedPayload({
+        kind: turn.role === "assistant" ? "assistant_text" : "user_message",
+        payload: block.text,
+      });
+    }
+    const lifecycle = createCompactionLifecycle();
+    const isAborted = () => lifecycle.getSignal().aborted;
+    let releaseGated: () => void = () => undefined;
+    const gatedFinished = new Promise<void>((resolve) => {
+      releaseGated = resolve;
+    });
+    const abortingArchive = {
+      ...archive,
+      certifyRange: async (ids: readonly string[]) => {
+        const certificate = await archive.certifyRange(ids);
+        lifecycle.abortCompaction("operator interrupt");
+        return certificate;
+      },
+    };
+    const wrapped = lifecycle.wrapCompactor(
+      createSessionPruningCompactor({
+        summarize,
+        onFolded: (info) => folds.push(info),
+        onFailure: (text) => notices.push(text),
+        isAborted,
+        compactionShape: { tailBudgetTokens: 1 },
+        wrapPruning: (pruning) => {
+          const gated = wrapCompactorWithCompletenessGate(
+            pruning,
+            abortingArchive,
+            { isAborted },
+          );
+          return {
+            name: gated.name,
+            version: gated.version,
+            apply: async (turns, ctx) => {
+              try {
+                return await gated.apply(turns, ctx);
+              } finally {
+                releaseGated();
+              }
+            },
+          };
+        },
+      }),
+    );
+    const result = await wrapped.apply(many as never, {
+      state: {} as never,
+      trigger: "test",
+    });
+    await gatedFinished;
+    expect(result.output).toBe(many);
+    expect(result.record.reason).toBe(COMPACTION_ABORTED_REASON);
+    expect(folds).toEqual([]);
+    expect(notices).toEqual([]);
+    const handoffs = (await archive.listOccurrences()).filter(
+      (occurrence) => occurrence.provenance === "compaction-handoff",
+    );
+    expect(handoffs).toEqual([]);
   });
 });
 
diff --git a/src/session/runtime-assembly.ts b/src/session/runtime-assembly.ts
index 58ab8e139..51e937b86 100644
--- a/src/session/runtime-assembly.ts
+++ b/src/session/runtime-assembly.ts
@@ -444,7 +444,7 @@ export interface SessionPruningCompactorArgs {
   /**
    * Wraps the inner pruning apply before fold-commit side effects.
    * assembleChatAgent passes the completeness gate here so a discarded
-   * fold never notices or prunes.
+   * fold never notices, prunes, or records a phantom compaction-handoff.
    */
   wrapPruning?: (pruning: Compactor) => Compactor;
 
diff --git a/src/tui/runner/session.ts b/src/tui/runner/session.ts
index 7683f59b4..1b3d21c67 100644
--- a/src/tui/runner/session.ts
+++ b/src/tui/runner/session.ts
@@ -697,6 +697,7 @@ export async function assembleTUISession(
         ? state.liveDefaultSource
         : state.liveSource.id,
     anthropicCachePrompt: () => config.anthropicCachePrompt,
+    isCompactionAborted: () => compactionLifecycle.getSignal().aborted,
     getCompactor: (wrapPruning) =>
       compactionLifecycle.wrapCompactor(
         createSessionPruningCompactor({