diff --git a/console/index.html b/console/index.html
index 1ae331d..a737b15 100644
--- a/console/index.html
+++ b/console/index.html
@@ -18,6 +18,7 @@
       </div>
     </header>
     <main class="content">
+      <section id="identity" class="identity-wrap"></section>
       <section class="logs">
         <nav class="tabs" id="tabs">
           <button class="tab is-active" data-target="log">Activity</button>
diff --git a/console/src/fixtures.ts b/console/src/fixtures.ts
index 7d579e8..b71cfbf 100644
--- a/console/src/fixtures.ts
+++ b/console/src/fixtures.ts
@@ -1,4 +1,4 @@
-import type { Deployment } from "./types";
+import type { Deployment, RuntimeContext } from "./types";
 
 // Stand-in data so the console renders without a live core. Mirrors the shape
 // studio-cp's `deploy_list` / `deploy_get` return. Swapped for the Tauri source
@@ -37,3 +37,25 @@ export const FIXTURE_DEPLOYMENTS: Deployment[] = [
     instances: [],
   },
 ];
+
+// Stand-in identity so the browser build renders the panel without a core.
+// A healthy example: a task role that matches its binding's expectation.
+export const FIXTURE_RUNTIME_CONTEXT: RuntimeContext = {
+  cluster: "oab",
+  principal:
+    "arn:aws:sts::504190915686:assumed-role/openab-orca-task-role/session",
+  principal_kind: "role",
+  scope: "504190915686",
+  location: "ap-east-2",
+  source: "container-credentials (task/pod role)",
+  caller_id: "AROAEXAMPLE:session",
+  binding: {
+    name: "prod",
+    profile: null,
+    region: "ap-east-2",
+    expected_principal:
+      "arn:aws:iam::504190915686:role/openab-orca-task-role",
+  },
+  expected_principal: "arn:aws:iam::504190915686:role/openab-orca-task-role",
+  identity_matches: true,
+};
diff --git a/console/src/main.ts b/console/src/main.ts
index 013d3c9..9be421a 100644
--- a/console/src/main.ts
+++ b/console/src/main.ts
@@ -1,11 +1,12 @@
 import { defaultSource } from "./source";
-import { renderRoster } from "./render";
+import { renderRoster, renderIdentity } from "./render";
 import { createPane, bindBackend, type Level } from "./log";
 
 const POLL_MS = 5000;
 const CLUSTER = "oab";
 
 const roster = document.getElementById("roster");
+const identityEl = document.getElementById("identity");
 const clusterLabel = document.getElementById("cluster-label");
 const pollStatus = document.getElementById("poll-status");
 const logEl = document.getElementById("log");
@@ -89,6 +90,19 @@ async function tick(): Promise<void> {
   }
 }
 
+// The effective managing identity for this cluster (ADR #19). Fetched once on
+// boot and refreshed when the roster recovers — it changes rarely, so it does
+// not need the 5s poll (and each call is a live STS lookup server-side).
+async function refreshIdentity(): Promise<void> {
+  if (!identityEl) return;
+  try {
+    renderIdentity(identityEl, await source.runtimeContext(CLUSTER));
+  } catch (e) {
+    note("error", `identity: ${errText(e)}`);
+    renderIdentity(identityEl, null);
+  }
+}
+
 // The Tauri command bridge — present only inside the desktop shell (the browser
 // build has no `__TAURI__`, so callers no-op / hide their UI).
 type Invoke = <T>(cmd: string, args?: Record<string, unknown>) => Promise<T>;
@@ -178,6 +192,7 @@ async function boot(): Promise<void> {
   note("info", `polling cluster "${CLUSTER}" every ${POLL_MS / 1000}s`);
   setupUpdater();
   await startCore();
+  void refreshIdentity();
   void tick();
   window.setInterval(() => void tick(), POLL_MS);
 }
diff --git a/console/src/render.test.ts b/console/src/render.test.ts
index 55b3458..e4f062f 100644
--- a/console/src/render.test.ts
+++ b/console/src/render.test.ts
@@ -1,7 +1,11 @@
 import { describe, it, expect } from "vitest";
-import { rosterHtml } from "./render";
-import { FIXTURE_DEPLOYMENTS } from "./fixtures";
-import { AGENT_STATES, type Deployment } from "./types";
+import { rosterHtml, identityHtml } from "./render";
+import { FIXTURE_DEPLOYMENTS, FIXTURE_RUNTIME_CONTEXT } from "./fixtures";
+import { AGENT_STATES, type Deployment, type RuntimeContext } from "./types";
+
+function ctx(partial: Partial<RuntimeContext>): RuntimeContext {
+  return { ...structuredClone(FIXTURE_RUNTIME_CONTEXT), ...partial };
+}
 
 function dep(partial: Partial<Deployment>): Deployment {
   return {
@@ -63,3 +67,52 @@ describe("rosterHtml", () => {
     expect(html).not.toContain("<x>");
   });
 });
+
+describe("identityHtml", () => {
+  it("shows principal, account, region and the role kind badge", () => {
+    const html = identityHtml(FIXTURE_RUNTIME_CONTEXT);
+    expect(html).toContain('class="kind k-role"');
+    expect(html).toContain("504190915686");
+    expect(html).toContain("ap-east-2");
+    expect(html).toContain("openab-orca-task-role");
+  });
+
+  it("flags a mismatch and shows the expected principal", () => {
+    const html = identityHtml(
+      ctx({
+        principal: "arn:aws:iam::916371022086:user/brett.chien",
+        principal_kind: "user",
+        scope: "916371022086",
+        identity_matches: false,
+      }),
+    );
+    expect(html).toContain('class="identity mismatch"');
+    expect(html).toContain("identity mismatch");
+    expect(html).toContain("class=\"kind k-user\"");
+    expect(html).toContain("arn:aws:iam::504190915686:role/openab-orca-task-role");
+  });
+
+  it("shows a matches verdict when identity_matches is true", () => {
+    expect(identityHtml(ctx({ identity_matches: true }))).toContain(
+      "matches expected",
+    );
+  });
+
+  it("shows no verdict when there is no expectation", () => {
+    const html = identityHtml(
+      ctx({ identity_matches: null, expected_principal: null }),
+    );
+    expect(html).not.toContain("mismatch");
+    expect(html).not.toContain("matches expected");
+  });
+
+  it("renders an unavailable state for null", () => {
+    expect(identityHtml(null)).toContain("identity unavailable");
+  });
+
+  it("escapes the principal ARN", () => {
+    const html = identityHtml(ctx({ principal: "<script>" }));
+    expect(html).toContain("&lt;script&gt;");
+    expect(html).not.toContain("<script>");
+  });
+});
diff --git a/console/src/render.ts b/console/src/render.ts
index 142c3fb..1df2fce 100644
--- a/console/src/render.ts
+++ b/console/src/render.ts
@@ -1,4 +1,4 @@
-import type { AgentState, Deployment } from "./types";
+import type { AgentState, Deployment, RuntimeContext } from "./types";
 
 const STATE_CLASS: Record<AgentState, string> = {
   Starting: "s-starting",
@@ -57,3 +57,59 @@ export function rosterHtml(deployments: Deployment[]): string {
 export function renderRoster(el: HTMLElement, deployments: Deployment[]): void {
   el.innerHTML = rosterHtml(deployments);
 }
+
+// ---- Runtime identity / context panel (ADR #19) ------------------------------
+
+const KIND_CLASS: Record<string, string> = {
+  role: "k-role",
+  user: "k-user",
+  unknown: "k-unknown",
+};
+
+function kindBadge(kind: string): string {
+  return `<span class="kind ${KIND_CLASS[kind] ?? "k-unknown"}">${escapeHtml(kind)}</span>`;
+}
+
+function field(label: string, value: string, mono = true): string {
+  const v = mono ? `<code>${escapeHtml(value)}</code>` : escapeHtml(value);
+  return `<div class="id-field"><span class="k">${label}</span>${v}</div>`;
+}
+
+// Pure: a RuntimeContext -> the identity panel HTML. `null` renders an
+// unavailable state (core not started / call failed). Highlights a mismatch
+// when the resolved principal doesn't satisfy the binding's expectation.
+export function identityHtml(ctx: RuntimeContext | null): string {
+  if (!ctx) {
+    return `<div class="identity"><span class="muted">identity unavailable</span></div>`;
+  }
+  const mismatch = ctx.identity_matches === false;
+  const matched = ctx.identity_matches === true;
+  const cls = mismatch ? "identity mismatch" : matched ? "identity ok" : "identity";
+  const binding = ctx.binding
+    ? field("binding", ctx.binding.name || ctx.binding.profile || "—", false)
+    : `<div class="id-field"><span class="k">binding</span><span class="muted">none (default chain)</span></div>`;
+  const verdict = mismatch
+    ? `<div class="id-warn">⚠ identity mismatch — expected <code>${escapeHtml(ctx.expected_principal ?? "")}</code></div>`
+    : matched
+      ? `<div class="id-ok">✓ matches expected principal</div>`
+      : "";
+  return `<div class="${cls}">
+      <div class="id-head">
+        <span class="id-label">managing</span>
+        <span class="id-cluster">${escapeHtml(ctx.cluster)}</span>
+        <span class="id-as">as</span> ${kindBadge(ctx.principal_kind)}
+      </div>
+      <div class="id-grid">
+        ${field("principal", ctx.principal || "—")}
+        ${field("account", ctx.scope || "—")}
+        ${field("region", ctx.location || "—")}
+        ${field("source", ctx.source || "—", false)}
+        ${binding}
+      </div>
+      ${verdict}
+    </div>`;
+}
+
+export function renderIdentity(el: HTMLElement, ctx: RuntimeContext | null): void {
+  el.innerHTML = identityHtml(ctx);
+}
diff --git a/console/src/source.ts b/console/src/source.ts
index 5cf2fef..3f66715 100644
--- a/console/src/source.ts
+++ b/console/src/source.ts
@@ -1,10 +1,11 @@
-import type { Deployment } from "./types";
-import { FIXTURE_DEPLOYMENTS } from "./fixtures";
+import type { Deployment, RuntimeContext } from "./types";
+import { FIXTURE_DEPLOYMENTS, FIXTURE_RUNTIME_CONTEXT } from "./fixtures";
 
 // A read source for the console. Desktop (Tauri → studio-cp) and the standalone
 // browser build implement this identically, so the UI never knows which it is.
 export interface Source {
   listDeployments(cluster?: string): Promise<Deployment[]>;
+  runtimeContext(cluster?: string): Promise<RuntimeContext>;
 }
 
 // Fixture-backed source for the standalone / browser build — no core required.
@@ -12,6 +13,9 @@ export class MockSource implements Source {
   async listDeployments(): Promise<Deployment[]> {
     return structuredClone(FIXTURE_DEPLOYMENTS);
   }
+  async runtimeContext(): Promise<RuntimeContext> {
+    return structuredClone(FIXTURE_RUNTIME_CONTEXT);
+  }
 }
 
 // Minimal shape of the Tauri global bridge (v2, `withGlobalTauri`). Accessed via
@@ -24,11 +28,20 @@ interface TauriGlobal {
 // Desktop source: invokes the Tauri `deploy_list` command, which bridges to
 // studio-cp. Active only inside the Tauri shell.
 export class TauriSource implements Source {
-  async listDeployments(cluster?: string): Promise<Deployment[]> {
+  private invoke(): <T>(
+    cmd: string,
+    args?: Record<string, unknown>,
+  ) => Promise<T> {
     const tauri = (globalThis as { __TAURI__?: TauriGlobal }).__TAURI__;
     const invoke = tauri?.core?.invoke;
     if (!invoke) throw new Error("Tauri bridge unavailable");
-    return invoke<Deployment[]>("deploy_list", { cluster });
+    return invoke;
+  }
+  async listDeployments(cluster?: string): Promise<Deployment[]> {
+    return this.invoke()<Deployment[]>("deploy_list", { cluster });
+  }
+  async runtimeContext(cluster?: string): Promise<RuntimeContext> {
+    return this.invoke()<RuntimeContext>("runtime_context", { cluster });
   }
 }
 
diff --git a/console/src/styles.css b/console/src/styles.css
index 4fc2c49..1f726fc 100644
--- a/console/src/styles.css
+++ b/console/src/styles.css
@@ -269,3 +269,88 @@ td.counts.warn {
 .s-stopped {
   background: var(--s-stopped);
 }
+
+/* ---- Runtime identity / context panel (ADR #19) ---- */
+.identity-wrap {
+  margin: 0 0 12px;
+}
+.identity {
+  border: 1px solid var(--border);
+  border-left: 3px solid var(--s-running);
+  border-radius: 6px;
+  background: var(--panel);
+  padding: 10px 12px;
+  font-size: 13px;
+}
+.identity.mismatch {
+  border-left-color: var(--s-unhealthy);
+}
+.identity.ok {
+  border-left-color: var(--ok);
+}
+.id-head {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  margin-bottom: 8px;
+}
+.id-label {
+  color: var(--muted);
+  text-transform: uppercase;
+  font-size: 11px;
+  letter-spacing: 0.04em;
+}
+.id-cluster {
+  font-weight: 600;
+}
+.id-as {
+  color: var(--muted);
+}
+.kind {
+  border-radius: 4px;
+  padding: 1px 6px;
+  font-size: 11px;
+  font-weight: 600;
+  border: 1px solid var(--border);
+}
+.kind.k-role {
+  color: var(--ok);
+}
+.kind.k-user {
+  color: var(--s-unhealthy);
+}
+.kind.k-unknown {
+  color: var(--muted);
+}
+.id-grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
+  gap: 4px 16px;
+}
+.id-field {
+  display: flex;
+  gap: 6px;
+  align-items: baseline;
+  min-width: 0;
+}
+.id-field .k {
+  color: var(--muted);
+  min-width: 64px;
+  flex: none;
+}
+.id-field code {
+  font-size: 12px;
+  overflow-wrap: anywhere;
+}
+.id-warn {
+  margin-top: 8px;
+  color: var(--s-unhealthy);
+  font-weight: 600;
+}
+.id-warn code {
+  font-weight: 400;
+}
+.id-ok {
+  margin-top: 8px;
+  color: var(--ok);
+}
diff --git a/console/src/types.ts b/console/src/types.ts
index 474096c..51ff090 100644
--- a/console/src/types.ts
+++ b/console/src/types.ts
@@ -33,3 +33,28 @@ export interface Deployment {
   ready: number;
   instances: InstancePhase[];
 }
+
+// The fleet binding in effect for a cluster (ADR #19). Mirrors oab-mcp's
+// `runtime_context.binding`.
+export interface FleetBinding {
+  name: string;
+  profile: string | null;
+  region: string | null;
+  expected_principal: string | null;
+}
+
+// The effective runtime identity/context the control plane resolved for a
+// cluster — mirrors oab-mcp's `runtime_context` tool (ADR #19). `identity_matches`
+// is `null` when the binding declares no `expected_principal`.
+export interface RuntimeContext {
+  cluster: string;
+  principal: string;
+  principal_kind: string; // "role" | "user" | "unknown"
+  scope: string; // AWS account id
+  location: string; // region
+  source: string;
+  caller_id: string;
+  binding: FleetBinding | null;
+  expected_principal: string | null;
+  identity_matches: boolean | null;
+}
diff --git a/src-tauri/src/lib.rs b/src-tauri/src/lib.rs
index f191380..881aeaf 100644
--- a/src-tauri/src/lib.rs
+++ b/src-tauri/src/lib.rs
@@ -96,6 +96,34 @@ async fn deploy_list(
     }
 }
 
+/// Bridge command: the effective runtime identity/context for a cluster (ADR
+/// #19), sourced through the bundled `oab-mcp` sidecar's `runtime_context` tool.
+/// The console renders "who am I managing this cluster as, against what account".
+#[tauri::command]
+async fn runtime_context(
+    core: tauri::State<'_, Core>,
+    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())?
+    };
+    match client
+        .call_tool("runtime_context", json!({ "cluster": cluster }))
+        .await
+    {
+        Ok(v) => Ok(v),
+        Err(e) => {
+            client.log("error", &format!("runtime_context: {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)]
@@ -163,6 +191,7 @@ pub fn run() {
         .invoke_handler(tauri::generate_handler![
             start_core,
             deploy_list,
+            runtime_context,
             check_update,
             install_update
         ])