diff --git a/console/src/main.ts b/console/src/main.ts
index fe5be55..51d9071 100644
--- a/console/src/main.ts
+++ b/console/src/main.ts
@@ -238,6 +238,57 @@ if (configEl) {
   });
 }
 
+// ---- start / stop (ADR-2 write model: stop = scale→0, start = scale→1) -------
+// Scale a deployment off (0) or on (1). Reversible — ECS keeps the Spec at
+// desiredCount 0 — so this needs no state store. On success `tick()` re-renders
+// the roster (which recycles the button DOM), so we only re-enable on error.
+async function scale(
+  action: "start" | "stop",
+  name: string,
+  namespace: string,
+  btn: HTMLButtonElement,
+): Promise<void> {
+  const size = action === "start" ? 1 : 0;
+  btn.disabled = true;
+  try {
+    await source.scaleDeployment(name, size, namespace, activeCluster);
+    note("info", `${action === "start" ? "started" : "stopped"} ${namespace}/${name}`);
+    await tick();
+  } catch (e) {
+    note("error", `${action} ${namespace}/${name}: ${errText(e)}`);
+    btn.disabled = false;
+  }
+}
+
+// One delegated listener on the roster. Start executes on click; Stop is
+// disruptive (kills the running instance, though reversible), so it arms on the
+// first click and only executes on a confirming second click within 3s — a
+// webview-safe confirm that needs no dialog plugin. The 5s poll re-renders the
+// roster and would reset an armed button on its own; the 3s timer is tighter.
+if (roster) {
+  roster.addEventListener("click", (ev) => {
+    const btn = (ev.target as HTMLElement).closest<HTMLButtonElement>("button.act");
+    if (!btn) return;
+    const action = btn.dataset.action;
+    const { name, namespace } = btn.dataset;
+    if ((action !== "start" && action !== "stop") || !name || !namespace) return;
+    if (action === "stop" && btn.dataset.armed !== "1") {
+      btn.dataset.armed = "1";
+      btn.textContent = "Confirm stop";
+      btn.classList.add("armed");
+      window.setTimeout(() => {
+        if (btn.isConnected && btn.dataset.armed === "1") {
+          btn.dataset.armed = "";
+          btn.textContent = "Stop";
+          btn.classList.remove("armed");
+        }
+      }, 3000);
+      return;
+    }
+    void scale(action, name, namespace, btn);
+  });
+}
+
 // The Tauri command bridge — present only inside the desktop shell (the browser
 // build has no `__TAURI__`, so callers no-op / hide their UI).
 type Invoke = <T>(cmd: string, args?: Record<string, unknown>) => Promise<T>;
diff --git a/console/src/render.test.ts b/console/src/render.test.ts
index c3f29ae..c2f2d5a 100644
--- a/console/src/render.test.ts
+++ b/console/src/render.test.ts
@@ -76,6 +76,29 @@ describe("rosterHtml", () => {
     expect(html).toContain("&lt;x&gt;");
     expect(html).not.toContain("<x>");
   });
+
+  it("offers Stop for a running deployment and Start for a stopped one", () => {
+    const html = rosterHtml([
+      dep({ name: "on", namespace: "prod", desired: 1 }),
+      dep({ name: "off", namespace: "prod", desired: 0, instances: [] }),
+    ]);
+    expect(html).toContain('data-action="stop"');
+    expect(html).toContain('data-action="start"');
+    expect(html).toContain(">Stop</button>");
+    expect(html).toContain(">Start</button>");
+  });
+
+  it("carries name + namespace on the action button for the scale call", () => {
+    const html = rosterHtml([dep({ name: "orca", namespace: "prod" })]);
+    expect(html).toContain('data-name="orca"');
+    expect(html).toContain('data-namespace="prod"');
+  });
+
+  it("escapes name + namespace in action button data attributes", () => {
+    const html = rosterHtml([dep({ name: '"x', namespace: "n" })]);
+    expect(html).toContain("&quot;x");
+    expect(html).not.toContain('data-name=""x"');
+  });
 });
 
 describe("identityHtml", () => {
diff --git a/console/src/render.ts b/console/src/render.ts
index ab7d41b..da6ca41 100644
--- a/console/src/render.ts
+++ b/console/src/render.ts
@@ -26,6 +26,19 @@ function badge(state: AgentState): string {
   return `<span class="badge ${STATE_CLASS[state]}">${state}</span>`;
 }
 
+// Start (scale→1) when the deployment is off, Stop (scale→0) when it's on.
+// Stop keeps the Spec — ECS retains the service at desiredCount 0 — so it's
+// reversible, no state store needed. The `data-*` carry the identity the
+// delegated handler needs; the managing credential is resolved per-cluster, so
+// the row only needs name + namespace (service = `oab-{namespace}-{name}`).
+function actionButton(d: Deployment): string {
+  const off = d.desired === 0;
+  const action = off ? "start" : "stop";
+  const label = off ? "Start" : "Stop";
+  const cls = off ? "act act-start" : "act act-stop";
+  return `<button class="${cls}" type="button" data-action="${action}" data-name="${escapeHtml(d.name)}" data-namespace="${escapeHtml(d.namespace)}">${label}</button>`;
+}
+
 function rowHtml(d: Deployment): string {
   const phases = d.instances.length
     ? d.instances.map((i) => badge(i.state)).join(" ")
@@ -36,6 +49,7 @@ function rowHtml(d: Deployment): string {
       <td class="name">${name}</td>
       <td class="counts ${health}">${d.ready}/${d.desired}<span class="muted"> · cur ${d.current}</span></td>
       <td class="phases">${phases}</td>
+      <td class="actions">${actionButton(d)}</td>
     </tr>`;
 }
 
@@ -76,7 +90,7 @@ export function rosterHtml(deployments: Deployment[]): string {
     .join("");
   return `<table class="roster">
       <thead>
-        <tr><th>Deployment</th><th>Ready / Desired</th><th>Instances · 6-state</th></tr>
+        <tr><th>Deployment</th><th>Ready / Desired</th><th>Instances · 6-state</th><th class="actions-h">Actions</th></tr>
       </thead>
       <tbody>${rows}</tbody>
     </table>`;
diff --git a/console/src/source.ts b/console/src/source.ts
index c2b58d0..f7c1f0b 100644
--- a/console/src/source.ts
+++ b/console/src/source.ts
@@ -14,6 +14,16 @@ export interface Source {
   // Persist the raw TOML `text` of the config file, returning the reloaded
   // config. Rejects (without writing) when the text doesn't parse.
   writeFleetConfig(text: string): Promise<FleetConfig>;
+  // Scale a deployment on (size 1) or off (size 0) — the start/stop action.
+  // Reversible: ECS keeps the Spec at desiredCount 0, so no state store is
+  // needed. `namespace` is required (the service is `oab-{namespace}-{name}`);
+  // the managing credential is resolved per-cluster from `cluster`.
+  scaleDeployment(
+    name: string,
+    size: 0 | 1,
+    namespace: string,
+    cluster?: string,
+  ): Promise<void>;
 }
 
 // Fixture-backed source for the standalone / browser build — no core required.
@@ -32,6 +42,9 @@ export class MockSource implements Source {
   async writeFleetConfig(text: string): Promise<FleetConfig> {
     return { ...structuredClone(FIXTURE_FLEET_CONFIG), text };
   }
+  // Browser preview: no core, so scaling is a no-op — the fixture roster is
+  // re-cloned each poll, so nothing would persist anyway.
+  async scaleDeployment(): Promise<void> {}
 }
 
 // Minimal shape of the Tauri global bridge (v2, `withGlobalTauri`). Accessed via
@@ -65,6 +78,19 @@ export class TauriSource implements Source {
   async writeFleetConfig(text: string): Promise<FleetConfig> {
     return this.invoke()<FleetConfig>("fleet_config_write", { text });
   }
+  async scaleDeployment(
+    name: string,
+    size: 0 | 1,
+    namespace: string,
+    cluster?: string,
+  ): Promise<void> {
+    await this.invoke()<unknown>("deploy_scale", {
+      name,
+      size,
+      namespace,
+      cluster,
+    });
+  }
 }
 
 // Pick a source: Tauri when running inside the shell, else the mock.
diff --git a/console/src/styles.css b/console/src/styles.css
index 99322e4..1fef15f 100644
--- a/console/src/styles.css
+++ b/console/src/styles.css
@@ -241,6 +241,43 @@ td.counts.warn {
   padding: 24px 10px;
 }
 
+/* ---- roster actions (start / stop) ---- */
+th.actions-h,
+td.actions {
+  text-align: right;
+  white-space: nowrap;
+}
+button.act {
+  cursor: pointer;
+  border: 1px solid var(--border);
+  border-radius: 5px;
+  background: var(--bg);
+  color: var(--muted);
+  font: inherit;
+  font-size: 12px;
+  padding: 3px 12px;
+}
+button.act:hover {
+  color: var(--text);
+}
+button.act-start:hover {
+  border-color: var(--s-running);
+  color: var(--s-running);
+}
+button.act-stop:hover {
+  border-color: var(--s-unhealthy);
+  color: var(--s-unhealthy);
+}
+button.act.armed {
+  border-color: var(--s-unhealthy);
+  background: var(--s-unhealthy);
+  color: #fff;
+}
+button.act:disabled {
+  opacity: 0.5;
+  cursor: default;
+}
+
 .badge {
   display: inline-block;
   padding: 2px 8px;
diff --git a/src-tauri/src/lib.rs b/src-tauri/src/lib.rs
index 2f6033e..6d8c955 100644
--- a/src-tauri/src/lib.rs
+++ b/src-tauri/src/lib.rs
@@ -169,6 +169,40 @@ async fn fleet_config_write(core: tauri::State<'_, Core>, text: String) -> Resul
     }
 }
 
+/// Bridge command: start (size 1) / stop (size 0) a deployment via the sidecar's
+/// `deploy_scale` tool (ADR-2 write model — stop = scale→0, start = scale→1; the
+/// Spec is kept by ECS, so it's reversible). An OAB service runs a single bot
+/// token, so size is 0/1 only; `namespace` is required upstream to resolve the
+/// service (`oab-{namespace}-{name}`) and the managing credential is per-cluster.
+#[tauri::command]
+async fn deploy_scale(
+    core: tauri::State<'_, Core>,
+    name: String,
+    size: i64,
+    namespace: Option<String>,
+    cluster: Option<String>,
+) -> Result<Value, String> {
+    let cluster = cluster.unwrap_or_else(default_cluster);
+    let client = {
+        let guard = core.0.lock().await;
+        guard
+            .as_ref()
+            .cloned()
+            .ok_or_else(|| "core not started yet".to_string())?
+    };
+    let mut params = json!({ "name": name, "size": size, "cluster": cluster });
+    if let Some(ns) = namespace {
+        params["namespace"] = json!(ns);
+    }
+    match client.call_tool("deploy_scale", params).await {
+        Ok(v) => Ok(v),
+        Err(e) => {
+            client.log("error", &format!("deploy_scale: {e}"));
+            Err(e)
+        }
+    }
+}
+
 /// What the frontend needs to render the "update available" state: the version
 /// on the release vs. what's running, plus the release notes.
 #[derive(serde::Serialize)]
@@ -239,6 +273,7 @@ pub fn run() {
             runtime_context,
             fleet_config,
             fleet_config_write,
+            deploy_scale,
             check_update,
             install_update
         ])