diff --git a/foundry/packages/client/src/app-client.ts b/foundry/packages/client/src/app-client.ts
index b0229d0..f59e816 100644
--- a/foundry/packages/client/src/app-client.ts
+++ b/foundry/packages/client/src/app-client.ts
@@ -26,6 +26,12 @@ export interface FoundryAppClient {
   resumeSubscription(organizationId: string): Promise<void>;
   reconnectGithub(organizationId: string): Promise<void>;
   recordSeatUsage(workspaceId: string): Promise<void>;
+  setMockDebugOrganizationState?(input: {
+    organizationId: string;
+    githubSyncStatus?: "pending" | "syncing" | "synced" | "error";
+    githubInstallationStatus?: "connected" | "install_required" | "reconnect_required";
+    runtimeStatus?: "healthy" | "error";
+  }): Promise<void>;
 }
 
 export interface CreateFoundryAppClientOptions {
diff --git a/foundry/packages/client/src/mock-app.ts b/foundry/packages/client/src/mock-app.ts
index a5922d9..070d07c 100644
--- a/foundry/packages/client/src/mock-app.ts
+++ b/foundry/packages/client/src/mock-app.ts
@@ -140,6 +140,12 @@ export interface MockFoundryAppClient {
   resumeSubscription(organizationId: string): Promise<void>;
   reconnectGithub(organizationId: string): Promise<void>;
   recordSeatUsage(workspaceId: string): void;
+  setMockDebugOrganizationState(input: {
+    organizationId: string;
+    githubSyncStatus?: MockGithubSyncStatus;
+    githubInstallationStatus?: MockGithubInstallationStatus;
+    runtimeStatus?: MockActorRuntimeStatus;
+  }): Promise<void>;
 }
 
 const STORAGE_KEY = "sandbox-agent-foundry:mock-app:v1";
@@ -174,6 +180,22 @@ function buildHealthyRuntimeState(): MockFoundryActorRuntimeState {
   };
 }
 
+function buildSampleRuntimeIssue(organization: MockFoundryOrganization): MockFoundryActorRuntimeIssue {
+  return {
+    actorId: `${organization.id}:github-state`,
+    actorType: "organization",
+    scopeId: organization.id,
+    scopeLabel: `${organization.settings.displayName} organization`,
+    message: "GitHub sync failed while refreshing repositories",
+    workflowId: "github-sync",
+    stepName: "full-sync",
+    attempt: 2,
+    willRetry: true,
+    retryDelayMs: 5000,
+    occurredAt: Date.now(),
+  };
+}
+
 function buildDefaultSnapshot(): MockFoundryAppSnapshot {
   return {
     auth: {
@@ -671,6 +693,50 @@ class MockFoundryAppStore implements MockFoundryAppClient {
     }));
   }
 
+  async setMockDebugOrganizationState(input: {
+    organizationId: string;
+    githubSyncStatus?: MockGithubSyncStatus;
+    githubInstallationStatus?: MockGithubInstallationStatus;
+    runtimeStatus?: MockActorRuntimeStatus;
+  }): Promise<void> {
+    await this.injectAsyncLatency();
+    this.requireOrganization(input.organizationId);
+    this.updateOrganization(input.organizationId, (organization) => {
+      const nextIssues =
+        input.runtimeStatus === "error" ? (organization.runtime.issues.length > 0 ? organization.runtime.issues : [buildSampleRuntimeIssue(organization)]) : [];
+      const nextRuntime =
+        input.runtimeStatus != null
+          ? {
+              ...organization.runtime,
+              status: input.runtimeStatus,
+              errorCount: nextIssues.length,
+              lastErrorAt: nextIssues[0]?.occurredAt ?? null,
+              issues: nextIssues,
+            }
+          : organization.runtime;
+      const nextSyncStatus = input.githubSyncStatus ?? organization.github.syncStatus;
+      return {
+        ...organization,
+        github: {
+          ...organization.github,
+          syncStatus: nextSyncStatus,
+          installationStatus: input.githubInstallationStatus ?? organization.github.installationStatus,
+          importedRepoCount: nextSyncStatus === "synced" ? organization.repoCatalog.length : organization.github.importedRepoCount,
+          lastSyncLabel:
+            nextSyncStatus === "syncing"
+              ? "Syncing repositories..."
+              : nextSyncStatus === "error"
+                ? "GitHub sync failed"
+                : nextSyncStatus === "pending"
+                  ? "Waiting to sync"
+                  : "Synced just now",
+          lastSyncAt: nextSyncStatus === "synced" ? Date.now() : organization.github.lastSyncAt,
+        },
+        runtime: nextRuntime,
+      };
+    });
+  }
+
   recordSeatUsage(workspaceId: string): void {
     const org = this.snapshot.organizations.find((candidate) => candidate.workspaceId === workspaceId);
     const currentUser = currentMockUser(this.snapshot);
diff --git a/foundry/packages/frontend/src/app/router.tsx b/foundry/packages/frontend/src/app/router.tsx
index 0d94406..def2808 100644
--- a/foundry/packages/frontend/src/app/router.tsx
+++ b/foundry/packages/frontend/src/app/router.tsx
@@ -2,6 +2,7 @@ import { type ReactNode, useEffect } from "react";
 import { setFrontendErrorContext } from "@sandbox-agent/foundry-frontend-errors/client";
 import type { FoundryBillingPlanId } from "@sandbox-agent/foundry-shared";
 import { Navigate, Outlet, createRootRoute, createRoute, createRouter, useRouterState } from "@tanstack/react-router";
+import { DevPanel } from "../components/dev-panel";
 import { MockLayout } from "../components/mock-layout";
 import {
   MockAccountSettingsPage,
@@ -344,6 +345,7 @@ function RootLayout() {
     <>
       <RouteContextSync />
       <Outlet />
+      <DevPanel />
     </>
   );
 }
diff --git a/foundry/packages/frontend/src/components/dev-panel.tsx b/foundry/packages/frontend/src/components/dev-panel.tsx
new file mode 100644
index 0000000..1d970b6
--- /dev/null
+++ b/foundry/packages/frontend/src/components/dev-panel.tsx
@@ -0,0 +1,323 @@
+import { useCallback, useEffect, useMemo, useState } from "react";
+import { useRouterState } from "@tanstack/react-router";
+import { Bug, RefreshCw, ShieldAlert, Wifi } from "lucide-react";
+import { useFoundryTokens } from "../app/theme";
+import { isMockFrontendClient } from "../lib/env";
+import { activeMockOrganization, activeMockUser, eligibleOrganizations, useMockAppClient, useMockAppSnapshot } from "../lib/mock-app";
+
+const DEV_PANEL_STORAGE_KEY = "sandbox-agent-foundry:dev-panel-visible";
+
+function readStoredVisibility(): boolean {
+  if (typeof window === "undefined") {
+    return true;
+  }
+  try {
+    const stored = window.localStorage.getItem(DEV_PANEL_STORAGE_KEY);
+    return stored == null ? true : stored === "true";
+  } catch {
+    return true;
+  }
+}
+
+function writeStoredVisibility(value: boolean): void {
+  if (typeof window === "undefined") {
+    return;
+  }
+  try {
+    window.localStorage.setItem(DEV_PANEL_STORAGE_KEY, String(value));
+  } catch {
+    // ignore
+  }
+}
+
+function sectionStyle(borderColor: string, background: string) {
+  return {
+    display: "grid",
+    gap: "10px",
+    padding: "12px",
+    borderRadius: "12px",
+    border: `1px solid ${borderColor}`,
+    background,
+  } as const;
+}
+
+function labelStyle(color: string) {
+  return {
+    fontSize: "11px",
+    fontWeight: 600,
+    letterSpacing: "0.04em",
+    textTransform: "uppercase" as const,
+    color,
+  };
+}
+
+export function DevPanel() {
+  if (!import.meta.env.DEV) {
+    return null;
+  }
+
+  const client = useMockAppClient();
+  const snapshot = useMockAppSnapshot();
+  const organization = activeMockOrganization(snapshot);
+  const user = activeMockUser(snapshot);
+  const organizations = eligibleOrganizations(snapshot);
+  const t = useFoundryTokens();
+  const location = useRouterState({ select: (state) => state.location });
+  const [visible, setVisible] = useState<boolean>(() => readStoredVisibility());
+
+  useEffect(() => {
+    writeStoredVisibility(visible);
+  }, [visible]);
+
+  useEffect(() => {
+    const onKeyDown = (event: KeyboardEvent) => {
+      if (event.shiftKey && event.key.toLowerCase() === "d") {
+        event.preventDefault();
+        setVisible((current) => !current);
+      }
+      if (event.key === "Escape") {
+        setVisible(false);
+      }
+    };
+    window.addEventListener("keydown", onKeyDown);
+    return () => window.removeEventListener("keydown", onKeyDown);
+  }, []);
+
+  const modeLabel = isMockFrontendClient ? "Mock" : "Live";
+  const github = organization?.github ?? null;
+  const runtime = organization?.runtime ?? null;
+  const runtimeSummary = useMemo(() => {
+    if (!runtime || runtime.errorCount === 0) {
+      return "No actor errors";
+    }
+    return runtime.errorCount === 1 ? "1 actor error" : `${runtime.errorCount} actor errors`;
+  }, [runtime]);
+
+  const pillButtonStyle = useCallback(
+    (active = false) =>
+      ({
+        border: `1px solid ${active ? t.accent : t.borderDefault}`,
+        background: active ? t.surfacePrimary : t.surfaceSecondary,
+        color: t.textPrimary,
+        borderRadius: "999px",
+        padding: "6px 10px",
+        fontSize: "11px",
+        fontWeight: 600,
+        cursor: "pointer",
+      }) as const,
+    [t],
+  );
+
+  if (!visible) {
+    return (
+      <button
+        type="button"
+        onClick={() => setVisible(true)}
+        style={{
+          position: "fixed",
+          right: "16px",
+          bottom: "16px",
+          zIndex: 1000,
+          display: "inline-flex",
+          alignItems: "center",
+          gap: "8px",
+          border: `1px solid ${t.borderDefault}`,
+          background: t.surfacePrimary,
+          color: t.textPrimary,
+          borderRadius: "999px",
+          padding: "10px 14px",
+          boxShadow: "0 18px 40px rgba(0, 0, 0, 0.28)",
+          cursor: "pointer",
+        }}
+      >
+        <Bug size={14} />
+        Dev
+      </button>
+    );
+  }
+
+  return (
+    <div
+      style={{
+        position: "fixed",
+        right: "16px",
+        bottom: "16px",
+        width: "360px",
+        maxHeight: "calc(100vh - 32px)",
+        overflowY: "auto",
+        zIndex: 1000,
+        borderRadius: "18px",
+        border: `1px solid ${t.borderDefault}`,
+        background: t.surfacePrimary,
+        color: t.textPrimary,
+        boxShadow: "0 24px 60px rgba(0, 0, 0, 0.35)",
+      }}
+    >
+      <div
+        style={{
+          position: "sticky",
+          top: 0,
+          display: "flex",
+          alignItems: "center",
+          justifyContent: "space-between",
+          padding: "14px 16px",
+          borderBottom: `1px solid ${t.borderDefault}`,
+          background: t.surfacePrimary,
+        }}
+      >
+        <div style={{ display: "grid", gap: "2px" }}>
+          <div style={{ display: "flex", alignItems: "center", gap: "8px" }}>
+            <Bug size={14} />
+            <strong style={{ fontSize: "13px" }}>Dev Panel</strong>
+            <span
+              style={{
+                fontSize: "10px",
+                fontWeight: 700,
+                letterSpacing: "0.06em",
+                textTransform: "uppercase",
+                color: t.textMuted,
+              }}
+            >
+              {modeLabel}
+            </span>
+          </div>
+          <div style={{ fontSize: "11px", color: t.textMuted }}>{location.pathname}</div>
+        </div>
+        <button type="button" onClick={() => setVisible(false)} style={pillButtonStyle()}>
+          Hide
+        </button>
+      </div>
+
+      <div style={{ display: "grid", gap: "12px", padding: "14px" }}>
+        <div style={sectionStyle(t.borderSubtle, t.surfaceSecondary)}>
+          <div style={labelStyle(t.textMuted)}>Session</div>
+          <div style={{ display: "grid", gap: "4px", fontSize: "12px" }}>
+            <div>Auth: {snapshot.auth.status}</div>
+            <div>User: {user ? `${user.name} (@${user.githubLogin})` : "None"}</div>
+            <div>Organization: {organization?.settings.displayName ?? "None selected"}</div>
+          </div>
+          {isMockFrontendClient ? (
+            <div style={{ display: "flex", gap: "8px", flexWrap: "wrap" }}>
+              {snapshot.auth.status === "signed_in" ? (
+                <button type="button" onClick={() => void client.signOut()} style={pillButtonStyle()}>
+                  Sign out
+                </button>
+              ) : (
+                snapshot.users.map((candidate) => (
+                  <button key={candidate.id} type="button" onClick={() => void client.signInWithGithub(candidate.id)} style={pillButtonStyle()}>
+                    Sign in as {candidate.githubLogin}
+                  </button>
+                ))
+              )}
+            </div>
+          ) : null}
+        </div>
+
+        <div style={sectionStyle(t.borderSubtle, t.surfaceSecondary)}>
+          <div style={labelStyle(t.textMuted)}>GitHub</div>
+          <div style={{ display: "grid", gap: "4px", fontSize: "12px" }}>
+            <div>Installation: {github?.installationStatus ?? "n/a"}</div>
+            <div>Sync: {github?.syncStatus ?? "n/a"}</div>
+            <div>Repos: {github?.importedRepoCount ?? 0}</div>
+            <div>Last sync: {github?.lastSyncLabel ?? "n/a"}</div>
+          </div>
+          {organization ? (
+            <div style={{ display: "flex", gap: "8px", flexWrap: "wrap" }}>
+              <button type="button" onClick={() => void client.triggerGithubSync(organization.id)} style={pillButtonStyle()}>
+                <RefreshCw size={12} style={{ marginRight: "6px", verticalAlign: "text-bottom" }} />
+                Sync
+              </button>
+              <button type="button" onClick={() => void client.reconnectGithub(organization.id)} style={pillButtonStyle()}>
+                <Wifi size={12} style={{ marginRight: "6px", verticalAlign: "text-bottom" }} />
+                Reconnect
+              </button>
+            </div>
+          ) : null}
+          {isMockFrontendClient && organization && client.setMockDebugOrganizationState ? (
+            <div style={{ display: "grid", gap: "8px" }}>
+              <div style={{ display: "flex", gap: "6px", flexWrap: "wrap" }}>
+                {(["pending", "syncing", "synced", "error"] as const).map((status) => (
+                  <button
+                    key={status}
+                    type="button"
+                    onClick={() => void client.setMockDebugOrganizationState?.({ organizationId: organization.id, githubSyncStatus: status })}
+                    style={pillButtonStyle(github?.syncStatus === status)}
+                  >
+                    {status}
+                  </button>
+                ))}
+              </div>
+              <div style={{ display: "flex", gap: "6px", flexWrap: "wrap" }}>
+                {(["connected", "install_required", "reconnect_required"] as const).map((status) => (
+                  <button
+                    key={status}
+                    type="button"
+                    onClick={() => void client.setMockDebugOrganizationState?.({ organizationId: organization.id, githubInstallationStatus: status })}
+                    style={pillButtonStyle(github?.installationStatus === status)}
+                  >
+                    {status}
+                  </button>
+                ))}
+              </div>
+            </div>
+          ) : null}
+        </div>
+
+        <div style={sectionStyle(t.borderSubtle, t.surfaceSecondary)}>
+          <div style={labelStyle(t.textMuted)}>Runtime</div>
+          <div style={{ display: "grid", gap: "4px", fontSize: "12px" }}>
+            <div>Status: {runtime?.status ?? "n/a"}</div>
+            <div>{runtimeSummary}</div>
+            {runtime?.issues[0] ? <div>Latest: {runtime.issues[0].message}</div> : null}
+          </div>
+          {organization ? (
+            <div style={{ display: "flex", gap: "8px", flexWrap: "wrap" }}>
+              {isMockFrontendClient && client.setMockDebugOrganizationState ? (
+                <>
+                  <button
+                    type="button"
+                    onClick={() => void client.setMockDebugOrganizationState?.({ organizationId: organization.id, runtimeStatus: "error" })}
+                    style={pillButtonStyle(runtime?.status === "error")}
+                  >
+                    <ShieldAlert size={12} style={{ marginRight: "6px", verticalAlign: "text-bottom" }} />
+                    Show error
+                  </button>
+                  <button
+                    type="button"
+                    onClick={() => void client.setMockDebugOrganizationState?.({ organizationId: organization.id, runtimeStatus: "healthy" })}
+                    style={pillButtonStyle(runtime?.status === "healthy")}
+                  >
+                    Healthy
+                  </button>
+                </>
+              ) : null}
+              {runtime?.errorCount ? (
+                <button type="button" onClick={() => void client.clearOrganizationRuntimeIssues(organization.id)} style={pillButtonStyle()}>
+                  Clear actor errors
+                </button>
+              ) : null}
+            </div>
+          ) : null}
+        </div>
+
+        {isMockFrontendClient && organizations.length > 0 ? (
+          <div style={sectionStyle(t.borderSubtle, t.surfaceSecondary)}>
+            <div style={labelStyle(t.textMuted)}>Mock Organization</div>
+            <div style={{ display: "flex", gap: "6px", flexWrap: "wrap" }}>
+              {organizations.map((candidate) => (
+                <button
+                  key={candidate.id}
+                  type="button"
+                  onClick={() => void client.selectOrganization(candidate.id)}
+                  style={pillButtonStyle(organization?.id === candidate.id)}
+                >
+                  {candidate.settings.displayName}
+                </button>
+              ))}
+            </div>
+          </div>
+        ) : null}
+      </div>
+    </div>
+  );
+}