diff --git a/.github/workflows/sync-models.yml b/.github/workflows/sync-models.yml
index f52656138..7edd03242 100644
--- a/.github/workflows/sync-models.yml
+++ b/.github/workflows/sync-models.yml
@@ -95,6 +95,7 @@ jobs:
         run: bun validate
 
       - name: Report changes
+        id: report
         env:
           GH_TOKEN: ${{ steps.committer.outputs.token }}
           BRANCH: automation/sync-models-${{ matrix.provider }}
@@ -119,9 +120,20 @@ jobs:
           git checkout -B "$BRANCH"
           git add models providers
           git commit -m "$TITLE"
-          git push --force-with-lease origin "$BRANCH"
+          bun sync:auto-merge HEAD^ HEAD
+          safe="$(sed -n 's/^safe=//p' "$GITHUB_OUTPUT" | tail -1)"
 
           pr_number="$(gh pr list --head "$BRANCH" --base dev --json number --jq '.[0].number')"
+          if [ "$safe" != "true" ] && [ -n "$pr_number" ]; then
+            gh pr merge "$pr_number" --disable-auto || true
+            if [ "$(gh pr view "$pr_number" --json autoMergeRequest --jq '.autoMergeRequest == null')" != "true" ]; then
+              echo "Failed to disable auto-merge for unsafe sync PR #$pr_number."
+              exit 1
+            fi
+          fi
+
+          git push --force-with-lease origin "$BRANCH"
+
           if [ -n "$pr_number" ]; then
             gh pr edit "$pr_number" --title "$TITLE" --body-file .sync/model-sync-report.md
             for label in "${labels[@]}"; do
@@ -129,4 +141,12 @@ jobs:
             done
           else
             gh pr create --base dev --head "$BRANCH" --title "$TITLE" --body-file .sync/model-sync-report.md "${label_args[@]}"
+            pr_number="$(gh pr list --head "$BRANCH" --base dev --json number --jq '.[0].number')"
+          fi
+
+          if [ "$safe" = "true" ]; then
+            gh pr merge "$pr_number" --auto --squash
+          elif [ "$(gh pr view "$pr_number" --json autoMergeRequest --jq '.autoMergeRequest == null')" != "true" ]; then
+            echo "Unsafe sync PR #$pr_number still has auto-merge enabled."
+            exit 1
           fi
diff --git a/package.json b/package.json
index cea23def3..a58fbffc0 100644
--- a/package.json
+++ b/package.json
@@ -37,7 +37,8 @@
     "digitalocean:sync": "bun ./packages/core/script/sync-models.ts digitalocean",
     "ambient:sync": "bun ./packages/core/script/sync-models.ts ambient",
     "models:sync": "bun ./packages/core/script/sync-models.ts",
-    "sync:models": "bun ./packages/core/script/sync-models.ts"
+    "sync:models": "bun ./packages/core/script/sync-models.ts",
+    "sync:auto-merge": "bun ./packages/core/script/check-sync-auto-merge.ts"
   },
   "dependencies": {
     "@cloudflare/workers-types": "^4.20260424.1",
diff --git a/packages/core/script/check-sync-auto-merge.ts b/packages/core/script/check-sync-auto-merge.ts
new file mode 100644
index 000000000..aacfa69d7
--- /dev/null
+++ b/packages/core/script/check-sync-auto-merge.ts
@@ -0,0 +1,22 @@
+import { appendFile } from "node:fs/promises";
+
+import { classifyAutoMerge, parseNameStatus } from "../src/sync/auto-merge.js";
+
+const base = process.argv[2] ?? "HEAD^";
+const head = process.argv[3] ?? "HEAD";
+const diff = Bun.spawnSync(["git", "diff", "--name-status", "--no-renames", base, head], {
+  stdout: "pipe",
+  stderr: "inherit",
+});
+
+if (diff.exitCode !== 0) process.exit(diff.exitCode ?? 1);
+
+const decision = await classifyAutoMerge(parseNameStatus(diff.stdout.toString()));
+const summary = decision.safe
+  ? `Safe to auto-merge: ${decision.created} created, ${decision.updated} updated, ${decision.deleted} deleted.`
+  : `Manual review required: ${decision.reasons.join("; ")}.`;
+
+console.log(summary);
+if (process.env.GITHUB_OUTPUT) {
+  await appendFile(process.env.GITHUB_OUTPUT, `safe=${decision.safe}\nsummary=${summary}\n`);
+}
diff --git a/packages/core/src/sync/auto-merge.ts b/packages/core/src/sync/auto-merge.ts
new file mode 100644
index 000000000..f26126723
--- /dev/null
+++ b/packages/core/src/sync/auto-merge.ts
@@ -0,0 +1,84 @@
+import { readFile } from "node:fs/promises";
+
+export const MAX_CREATED_MODELS = 10;
+export const MAX_DELETED_MODELS = 10;
+export const MAX_MODEL_CHURN = 15;
+const REVIEWED_REASONING_PROVIDERS = new Set(["openrouter"]);
+
+export interface CatalogChange {
+  status: "created" | "updated" | "deleted";
+  path: string;
+}
+
+export interface AutoMergeDecision {
+  safe: boolean;
+  created: number;
+  updated: number;
+  deleted: number;
+  reasons: string[];
+}
+
+function isModel(path: string) {
+  return path.endsWith(".toml") && (path.startsWith("models/") || path.includes("/models/"));
+}
+
+function isProviderModel(path: string) {
+  return path.endsWith(".toml") && path.startsWith("providers/") && path.includes("/models/");
+}
+
+export async function classifyAutoMerge(
+  changes: CatalogChange[],
+  load = (path: string) => readFile(path, "utf8"),
+): Promise<AutoMergeDecision> {
+  const models = changes.filter((change) => isModel(change.path));
+  const created = models.filter((change) => change.status === "created").length;
+  const updated = models.filter((change) => change.status === "updated").length;
+  const deleted = models.filter((change) => change.status === "deleted").length;
+  const reasons: string[] = [];
+
+  if (created > MAX_CREATED_MODELS) reasons.push(`${created} models created (limit ${MAX_CREATED_MODELS})`);
+  if (deleted > MAX_DELETED_MODELS) reasons.push(`${deleted} models deleted (limit ${MAX_DELETED_MODELS})`);
+  if (created + deleted > MAX_MODEL_CHURN) {
+    reasons.push(`${created + deleted} models created or deleted (limit ${MAX_MODEL_CHURN})`);
+  }
+
+  for (const change of models) {
+    if (change.status === "deleted" || !isProviderModel(change.path)) continue;
+
+    const model = Bun.TOML.parse(await load(change.path)) as Record<string, unknown>;
+    let reasoning = model.reasoning;
+    if (reasoning === undefined && typeof model.base_model === "string") {
+      const base = Bun.TOML.parse(await load(`models/${model.base_model}.toml`)) as Record<string, unknown>;
+      reasoning = base.reasoning;
+    }
+
+    if (reasoning === true) {
+      if (!Object.hasOwn(model, "reasoning_options")) {
+        reasons.push(`${change.path} is a reasoning model without explicit reasoning_options`);
+      } else if (!REVIEWED_REASONING_PROVIDERS.has(change.path.split("/")[1]!)) {
+        reasons.push(`${change.path} is a reasoning model that requires manual review`);
+      }
+    }
+  }
+
+  return { safe: reasons.length === 0, created, updated, deleted, reasons };
+}
+
+export function parseNameStatus(output: string): CatalogChange[] {
+  return output.trim().split("\n").filter(Boolean).flatMap((line) => {
+    const [code, ...paths] = line.split("\t");
+    const path = paths.at(-1);
+    if (!code || !path) throw new Error(`Invalid git diff entry: ${line}`);
+    if (code.startsWith("R")) {
+      if (paths.length !== 2) throw new Error(`Invalid git rename entry: ${line}`);
+      return [
+        { status: "deleted", path: paths[0]! },
+        { status: "created", path: paths[1]! },
+      ];
+    }
+    return {
+      status: code.startsWith("A") ? "created" : code.startsWith("D") ? "deleted" : "updated",
+      path,
+    };
+  });
+}
diff --git a/packages/core/test/auto-merge.test.ts b/packages/core/test/auto-merge.test.ts
new file mode 100644
index 000000000..c2d0ae74b
--- /dev/null
+++ b/packages/core/test/auto-merge.test.ts
@@ -0,0 +1,81 @@
+import { expect, test } from "bun:test";
+
+import { classifyAutoMerge, parseNameStatus } from "../src/sync/auto-merge.js";
+
+const fullModel = (reasoning: boolean, options?: string) => `
+name = "Test"
+description = "Test model"
+reasoning = ${reasoning}
+${options ?? ""}
+`;
+
+test("allows unlimited updates and bounded model churn", async () => {
+  const changes = Array.from({ length: 30 }, (_, index) => ({
+    status: "updated" as const,
+    path: `providers/test/models/model-${index}.toml`,
+  }));
+  const decision = await classifyAutoMerge(changes, async () => fullModel(false));
+
+  expect(decision.safe).toBe(true);
+  expect(decision.updated).toBe(30);
+});
+
+test("requires manual review for bulk additions", async () => {
+  const changes = Array.from({ length: 11 }, (_, index) => ({
+    status: "created" as const,
+    path: `providers/test/models/model-${index}.toml`,
+  }));
+  const decision = await classifyAutoMerge(changes, async () => fullModel(false));
+
+  expect(decision.safe).toBe(false);
+  expect(decision.reasons).toContain("11 models created (limit 10)");
+});
+
+test("requires manual review for reasoning provider models", async () => {
+  const withoutOptions = await classifyAutoMerge(
+    [{ status: "updated", path: "providers/test/models/reasoner.toml" }],
+    async () => fullModel(true),
+  );
+  const withOptions = await classifyAutoMerge(
+    [{ status: "updated", path: "providers/test/models/reasoner.toml" }],
+    async () => fullModel(true, "reasoning_options = []"),
+  );
+
+  expect(withoutOptions.safe).toBe(false);
+  expect(withOptions.safe).toBe(false);
+});
+
+test("allows reviewed providers with explicit reasoning options", async () => {
+  const decision = await classifyAutoMerge(
+    [{ status: "updated", path: "providers/openrouter/models/reasoner.toml" }],
+    async () => fullModel(true, "reasoning_options = []"),
+  );
+
+  expect(decision.safe).toBe(true);
+});
+
+test("resolves reasoning from base model", async () => {
+  const decision = await classifyAutoMerge(
+    [{ status: "created", path: "providers/test/models/reasoner.toml" }],
+    async (path) => path.startsWith("models/") ? fullModel(true) : 'base_model = "lab/reasoner"\n',
+  );
+
+  expect(decision.safe).toBe(false);
+});
+
+test("parses additions, modifications, and deletions", () => {
+  expect(parseNameStatus("A\tmodels/a.toml\nM\tmodels/b.toml\nD\tmodels/c.toml\n"))
+    .toEqual([
+      { status: "created", path: "models/a.toml" },
+      { status: "updated", path: "models/b.toml" },
+      { status: "deleted", path: "models/c.toml" },
+    ]);
+});
+
+test("counts unexpected renames as a deletion and creation", () => {
+  expect(parseNameStatus("R100\tmodels/old.toml\tmodels/new.toml\n"))
+    .toEqual([
+      { status: "deleted", path: "models/old.toml" },
+      { status: "created", path: "models/new.toml" },
+    ]);
+});