diff --git a/client/src/hooks/use-consilium-loops.ts b/client/src/hooks/use-consilium-loops.ts
index 870552b..12a9a40 100644
--- a/client/src/hooks/use-consilium-loops.ts
+++ b/client/src/hooks/use-consilium-loops.ts
@@ -518,9 +518,12 @@ export function useApproveMerge() {
  */
 export function useDevelopLoop() {
   const qc = useQueryClient();
-  return useMutation<ConsiliumLoopRow, Error, string>({
-    mutationFn: (id) => apiRequest("POST", `${LIST_KEY}/${id}/develop`),
-    onSuccess: (_data, id) => {
+  return useMutation<ConsiliumLoopRow, Error, { id: string; scope?: "p0" | "all" }>({
+    // MR-size control: `scope: "p0"` develops only the P0s (small reviewable MR);
+    // omitted/"all" keeps the historical full-verdict round.
+    mutationFn: ({ id, scope }) =>
+      apiRequest("POST", `${LIST_KEY}/${id}/develop`, scope ? { scope } : undefined),
+    onSuccess: (_data, { id }) => {
       qc.invalidateQueries({ queryKey: [LIST_KEY, id] });
       qc.invalidateQueries({ queryKey: [LIST_KEY] });
     },
diff --git a/client/src/pages/ConsiliumLoopDetail.tsx b/client/src/pages/ConsiliumLoopDetail.tsx
index b14ba87..826dedd 100644
--- a/client/src/pages/ConsiliumLoopDetail.tsx
+++ b/client/src/pages/ConsiliumLoopDetail.tsx
@@ -1586,7 +1586,7 @@ function ReviewGateActions({
 
   async function handleDevelop() {
     try {
-      await developLoop.mutateAsync(loopId);
+      await developLoop.mutateAsync({ id: loopId });
       toast({
         title: "Handed off to SDLC",
         description: "The developing round has started — follow the progress below.",
@@ -2757,6 +2757,8 @@ export default function ConsiliumLoopDetail() {
   const approveMerge = useApproveMerge();
   const developLoop = useDevelopLoop();
   const [confirmOpen, setConfirmOpen] = useState(false);
+  // MR-size control: the develop-scope chooser (Only P0s vs all action points).
+  const [developScopeOpen, setDevelopScopeOpen] = useState(false);
 
   if (isLoading) {
     return (
@@ -2804,6 +2806,11 @@ export default function ConsiliumLoopDetail() {
   const latestActionPointCount = Array.isArray(latestRound?.openActionPoints)
     ? latestRound!.openActionPoints.length
     : 0;
+  // MR-size control: P0 slice of the latest verdict — offered as a smaller round.
+  const latestP0Count = Array.isArray(latestRound?.openActionPoints)
+    ? (latestRound!.openActionPoints as ActionPoint[]).filter((ap) => ap.priority === "P0")
+        .length
+    : 0;
   const canDevelop =
     isVerdictTerminalLoopState(loop.state) && latestActionPointCount > 0;
 
@@ -2877,12 +2884,19 @@ export default function ConsiliumLoopDetail() {
     }
   }
 
-  async function handleDevelop() {
+  async function handleDevelop(scopeArg?: unknown) {
+    // Normalize: plain onClick callers pass a click event — only the two literal
+    // scopes ride to the server; anything else means "all" (historical behaviour).
+    const scope = scopeArg === "p0" || scopeArg === "all" ? scopeArg : undefined;
+    setDevelopScopeOpen(false);
     try {
-      await developLoop.mutateAsync(id);
+      await developLoop.mutateAsync({ id, scope });
       toast({
         title: "Handed off to SDLC",
-        description: "The developing round has started — follow the progress below.",
+        description:
+          scope === "p0"
+            ? `Developing only the P0 action points — merge that MR and the next round carries the rest.`
+            : "The developing round has started — follow the progress below.",
       });
     } catch (err) {
       // 400 (NO_ACTION_POINTS / REPO_NOT_*) | 409 (WRONG_STATE /
@@ -2950,7 +2964,13 @@ export default function ConsiliumLoopDetail() {
             {canDevelop && (
               <Button
                 size="sm"
-                onClick={handleDevelop}
+                onClick={() =>
+                  // A meaningful scope choice exists only when the verdict has BOTH
+                  // P0s and non-P0s — otherwise hand off the full list directly.
+                  latestP0Count > 0 && latestP0Count < latestActionPointCount
+                    ? setDevelopScopeOpen(true)
+                    : handleDevelop()
+                }
                 disabled={developLoop.isPending}
               >
                 {developLoop.isPending ? (
@@ -3181,6 +3201,34 @@ export default function ConsiliumLoopDetail() {
       </div>
 
       {/* Approve-merge confirm — the autonomy→production HITL gate */}
+      {/* MR-size control: choose the develop round's scope. One MR per round —
+          shipping only the P0s keeps it reviewable; the loop's NEXT round
+          re-derives and carries the remainder after the merge. */}
+      <AlertDialog open={developScopeOpen} onOpenChange={setDevelopScopeOpen}>
+        <AlertDialogContent>
+          <AlertDialogHeader>
+            <AlertDialogTitle className="flex items-center gap-2">
+              <Hammer className="h-5 w-5 text-primary" />
+              How much of the verdict should this round implement?
+            </AlertDialogTitle>
+            <AlertDialogDescription>
+              Each develop round produces ONE merge request. A smaller round is easier
+              to review — after you merge it, the next review round picks up the
+              remaining action points automatically.
+            </AlertDialogDescription>
+          </AlertDialogHeader>
+          <AlertDialogFooter>
+            <AlertDialogCancel>Cancel</AlertDialogCancel>
+            <AlertDialogAction onClick={() => void handleDevelop("p0")}>
+              Only P0s ({latestP0Count}) — small MR
+            </AlertDialogAction>
+            <AlertDialogAction onClick={() => void handleDevelop("all")}>
+              All action points ({latestActionPointCount})
+            </AlertDialogAction>
+          </AlertDialogFooter>
+        </AlertDialogContent>
+      </AlertDialog>
+
       <AlertDialog open={confirmOpen} onOpenChange={setConfirmOpen}>
         <AlertDialogContent>
           <AlertDialogHeader>
diff --git a/server/routes/consilium-loops.ts b/server/routes/consilium-loops.ts
index 4333997..1b23b33 100644
--- a/server/routes/consilium-loops.ts
+++ b/server/routes/consilium-loops.ts
@@ -400,7 +400,16 @@ export function registerConsiliumLoopRoutes(
   app.post("/api/consilium-loops/:id/develop", async (req: Request, res: Response) => {
     const auth = await authorizeConsiliumLoop(req, res, storage, String(req.params.id));
     if (!auth) return;
-    const result = await controller.develop(auth.loop.id);
+    // MR-size control: optional `scope` narrows the round to the P0s — the operator
+    // ships a small reviewable MR and lets the next round carry the remainder.
+    const rawScope = (req.body as { scope?: unknown } | undefined)?.scope;
+    if (rawScope !== undefined && rawScope !== "p0" && rawScope !== "all") {
+      return res.status(400).json({ error: 'scope must be "p0" or "all"' });
+    }
+    const result =
+      rawScope !== undefined
+        ? await controller.develop(auth.loop.id, { scope: rawScope })
+        : await controller.develop(auth.loop.id);
     if (result.ok) {
       const isAdmin = req.user?.role === "admin";
       // 200 + the masked loop row (state is now "developing"); the client polls
diff --git a/server/services/consilium/consilium-loop-controller.ts b/server/services/consilium/consilium-loop-controller.ts
index d2478ba..9918338 100644
--- a/server/services/consilium/consilium-loop-controller.ts
+++ b/server/services/consilium/consilium-loop-controller.ts
@@ -1255,14 +1255,25 @@ export class ConsiliumLoopController {
    * developing phase runs, via a synthetic verdict carrying the FULL action-point
    * list (the close-out reads only `verdict.openActionPoints`).
    */
-  async develop(loopId: string): Promise<DevelopResult> {
+  async develop(
+    loopId: string,
+    opts?: { scope?: "p0" | "all" },
+  ): Promise<DevelopResult> {
     const loop = await this.storage.getLoop(loopId);
     if (!loop) return { ok: false, code: "NOT_FOUND" };
     if (!isDevelopPromotable(loop.state, loop.reviewGate)) return { ok: false, code: "WRONG_STATE" };
 
     // FULL action points (ALL priorities) — SERVER-READ from the verdict; the
     // close-out reads only `openActionPoints`, but openP0 feeds the round audit.
-    const actionPoints = await this.resolveDevActionPoints(loop);
+    const allActionPoints = await this.resolveDevActionPoints(loop);
+    // MR-SIZE CONTROL: `scope: "p0"` develops ONLY the P0s — one small, reviewable
+    // MR per round; after its merge the loop's next review round re-derives the
+    // remainder and the operator ships it as the NEXT round's MR. Default "all"
+    // (absent opts) is byte-identical to the historical full-list handoff.
+    const actionPoints =
+      opts?.scope === "p0"
+        ? allActionPoints.filter((ap) => ap.priority === P0_PRIORITY)
+        : allActionPoints;
     if (actionPoints.length === 0) return { ok: false, code: "NO_ACTION_POINTS" };
 
     // Re-validate the persisted repoPath: global allowlist THEN project workspace.
diff --git a/tests/unit/consilium/consilium-loops-develop-route.test.ts b/tests/unit/consilium/consilium-loops-develop-route.test.ts
index c02576f..51a1939 100644
--- a/tests/unit/consilium/consilium-loops-develop-route.test.ts
+++ b/tests/unit/consilium/consilium-loops-develop-route.test.ts
@@ -103,6 +103,27 @@ describe("POST /api/consilium-loops/:id/develop", () => {
     expect((controller.develop as ReturnType<typeof vi.fn>)).toHaveBeenCalledWith(LOOP_ID);
   });
 
+  it('MR-size control: scope:"p0" is validated and passed through to the controller', async () => {
+    const { app, controller } = makeApp();
+    const res = await request(app)
+      .post(`/api/consilium-loops/${LOOP_ID}/develop`)
+      .send({ scope: "p0" });
+    expect(res.status).toBe(200);
+    expect(controller.develop as ReturnType<typeof vi.fn>).toHaveBeenCalledWith(LOOP_ID, {
+      scope: "p0",
+    });
+  });
+
+  it("MR-size control: an unknown scope → 400, develop NOT called", async () => {
+    const { app, controller } = makeApp();
+    const res = await request(app)
+      .post(`/api/consilium-loops/${LOOP_ID}/develop`)
+      .send({ scope: "everything" });
+    expect(res.status).toBe(400);
+    expect(String(res.body.error)).toContain("scope");
+    expect(controller.develop).not.toHaveBeenCalled();
+  });
+
   it("admin keeps createdBy in the masked row", async () => {
     const { app } = makeApp({ user: { id: "admin-x", role: "admin" } });
     const res = await request(app).post(`/api/consilium-loops/${LOOP_ID}/develop`).send();