diff --git a/src/app/api/issues/unclaim/route.test.ts b/src/app/api/issues/unclaim/route.test.ts
index 45853efb..dbe0a15b 100644
--- a/src/app/api/issues/unclaim/route.test.ts
+++ b/src/app/api/issues/unclaim/route.test.ts
@@ -244,16 +244,10 @@ describe("POST /api/issues/unclaim — operator path", () => {
       const res = await basicAuthRequest();
       expect(res.status).toBe(200);
 
-      expect(mocks.updateIssueLabels).toHaveBeenCalledWith(
-        "org/repo",
-        42,
-        expect.arrayContaining(["status/ready"]),
-      );
-      expect(mocks.updateIssueLabels).toHaveBeenCalledWith(
-        "org/repo",
-        42,
-        expect.not.arrayContaining(["status/in-progress"]),
-      );
+      // Status transition uses targeted add/remove, not a full-set write.
+      expect(mocks.removeIssueLabel).toHaveBeenCalledWith("org/repo", 42, "status/in-progress");
+      expect(mocks.addIssueLabel).toHaveBeenCalledWith("org/repo", 42, "status/ready");
+      expect(mocks.updateIssueLabels).not.toHaveBeenCalled();
       expect(mocks.updateIssue).toHaveBeenCalledWith({
         where: { id: "issue-1" },
         data: expect.objectContaining({
@@ -308,9 +302,12 @@ describe("POST /api/issues/unclaim — status handling", () => {
     expect(body.labels).toEqual(["status/ready"]);
     expect(body.status).toBe("status/ready");
     expect(body.statusNote).toBeNull();
-    expect(mocks.updateIssueLabels).toHaveBeenCalledWith("org/repo", 42, [
-      "status/ready",
-    ]);
+    // Targeted label writes: remove agent label, remove old status, add new status.
+    expect(mocks.removeIssueLabel).toHaveBeenCalledWith("org/repo", 42, "agent/test-agent");
+    expect(mocks.removeIssueLabel).toHaveBeenCalledWith("org/repo", 42, "status/in-progress");
+    expect(mocks.addIssueLabel).toHaveBeenCalledWith("org/repo", 42, "status/ready");
+    // Full-set write must never be used — it would revert labels changed on GitHub.
+    expect(mocks.updateIssueLabels).not.toHaveBeenCalled();
     expect(mocks.updateIssue).toHaveBeenCalledWith({
       where: { id: "issue-1" },
       data: expect.objectContaining({ labels: ["status/ready"] }),
@@ -332,9 +329,10 @@ describe("POST /api/issues/unclaim — status handling", () => {
     expect(body.labels).toEqual(["status/ready"]);
     expect(body.status).toBe("status/ready");
     expect(body.statusNote).toBeNull();
-    expect(mocks.updateIssueLabels).toHaveBeenCalledWith("org/repo", 42, [
-      "status/ready",
-    ]);
+    expect(mocks.removeIssueLabel).toHaveBeenCalledWith("org/repo", 42, "agent/test-agent");
+    expect(mocks.removeIssueLabel).toHaveBeenCalledWith("org/repo", 42, "status/blocked");
+    expect(mocks.addIssueLabel).toHaveBeenCalledWith("org/repo", 42, "status/ready");
+    expect(mocks.updateIssueLabels).not.toHaveBeenCalled();
     expect(mocks.updateIssue).toHaveBeenCalledWith({
       where: { id: "issue-1" },
       data: expect.objectContaining({ labels: ["status/ready"] }),
@@ -356,9 +354,10 @@ describe("POST /api/issues/unclaim — status handling", () => {
     expect(body.labels).toEqual(["status/blocked"]);
     expect(body.status).toBe("status/blocked");
     expect(body.statusNote).toContain("blockedReason is set");
-    expect(mocks.updateIssueLabels).toHaveBeenCalledWith("org/repo", 42, [
-      "status/blocked",
-    ]);
+    // No status transition — only the agent label is removed.
+    expect(mocks.removeIssueLabel).toHaveBeenCalledWith("org/repo", 42, "agent/test-agent");
+    expect(mocks.addIssueLabel).not.toHaveBeenCalled();
+    expect(mocks.updateIssueLabels).not.toHaveBeenCalled();
     expect(mocks.updateIssue).toHaveBeenCalledWith({
       where: { id: "issue-1" },
       data: expect.objectContaining({ labels: ["status/blocked"] }),
@@ -385,9 +384,10 @@ describe("POST /api/issues/unclaim — status handling", () => {
     expect(body.status).toBe("status/in-review");
     expect(body.statusNote).toContain("PR #7 is still open");
     expect(mocks.fetchPullRequestState).toHaveBeenCalledWith("org/repo", 7);
-    expect(mocks.updateIssueLabels).toHaveBeenCalledWith("org/repo", 42, [
-      "status/in-review",
-    ]);
+    // No status transition — only the agent label is removed.
+    expect(mocks.removeIssueLabel).toHaveBeenCalledWith("org/repo", 42, "agent/test-agent");
+    expect(mocks.addIssueLabel).not.toHaveBeenCalled();
+    expect(mocks.updateIssueLabels).not.toHaveBeenCalled();
     expect(mocks.updateIssue).toHaveBeenCalledWith({
       where: { id: "issue-1" },
       data: expect.objectContaining({ labels: ["status/in-review"] }),
@@ -474,7 +474,7 @@ describe("POST /api/issues/unclaim — guards", () => {
   });
 
   it("writes failure audit log when GitHub API fails", async () => {
-    mocks.updateIssueLabels.mockRejectedValueOnce(new Error("github 500"));
+    mocks.removeIssueLabel.mockRejectedValueOnce(new Error("github 500"));
 
     const res = await postRequest();
     expect(res.status).toBe(500);
@@ -500,6 +500,8 @@ describe("POST /api/issues/unclaim — guards", () => {
     const res = await postRequest();
     expect(res.status).toBe(200);
 
+    expect(mocks.removeIssueLabel).toHaveBeenCalledWith("org/repo", 42, "agent/test-agent");
+    expect(mocks.updateIssueLabels).not.toHaveBeenCalled();
     expect(mocks.updateIssue).toHaveBeenCalledWith({
       where: { id: "issue-1" },
       data: expect.objectContaining({
@@ -507,4 +509,24 @@ describe("POST /api/issues/unclaim — guards", () => {
       }),
     });
   });
+
+  it("does not revert labels changed on GitHub since the last sync (stale cache)", async () => {
+    // Cache is behind GitHub: status/ready was already cleared on GitHub and
+    // a blocked/* label was added there. A full-set write from this stale row
+    // would restore status/ready and delete the blocked label.
+    mocks.findUnique.mockResolvedValueOnce({
+      id: "issue-1",
+      state: "open",
+      labels: ["agent/test-agent", "status/ready"],
+    } as never);
+
+    const res = await postRequest();
+    expect(res.status).toBe(200);
+
+    // Only the agent label is removed; no full-set write touches any other label.
+    expect(mocks.removeIssueLabel).toHaveBeenCalledTimes(1);
+    expect(mocks.removeIssueLabel).toHaveBeenCalledWith("org/repo", 42, "agent/test-agent");
+    expect(mocks.addIssueLabel).not.toHaveBeenCalled();
+    expect(mocks.updateIssueLabels).not.toHaveBeenCalled();
+  });
 });
\ No newline at end of file
diff --git a/src/lib/issue-claim.ts b/src/lib/issue-claim.ts
index b4bdcb00..41d06f82 100644
--- a/src/lib/issue-claim.ts
+++ b/src/lib/issue-claim.ts
@@ -1,5 +1,5 @@
 import { AGENT_PREFIX, getAgentFromLabels } from "@/types";
-import { removeIssueLabel, updateIssueLabels } from "@/lib/github";
+import { removeIssueLabel } from "@/lib/github";
 import { transitionIssueStatus } from "@/lib/issue-status";
 import { fetchPullRequestState } from "@/lib/github-prs";
 
@@ -151,9 +151,11 @@ export async function releaseIssueClaim(params: {
     }
   }
 
-  // Preserve the established full-label update for operator unclaims, then
-  // defensively DELETE the agent label in case the cache was stale.
-  await updateIssueLabels(repoFullName, issueNumber, updatedLabels);
+  // Only targeted label writes reach GitHub here: the agent label is removed
+  // directly and any status transition goes through transitionIssueStatus,
+  // which itself uses add/remove primitives. Never replace the whole label
+  // set — the cached row can be behind GitHub, and a full-set write would
+  // silently revert every label change made on GitHub since the last sync.
   await removeIssueLabel(repoFullName, issueNumber, agentLabel);
 
   await prisma.issue.update({