diff --git a/pi-slate/CHANGELOG.md b/pi-slate/CHANGELOG.md
index 9c99721..e5a95ea 100644
--- a/pi-slate/CHANGELOG.md
+++ b/pi-slate/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+### Fixed
+
+- Native MCP validation is used on newer Pi versions by default. Missing validation is a warning, not a configuration failure.
+
 ## 0.1.18
 
 Pi 1.4.0 compatibility, session titles, and an opt-in effort-colored composer frame.
diff --git a/pi-slate/extensions/pi-slate/sidebar-data.ts b/pi-slate/extensions/pi-slate/sidebar-data.ts
index 7e0f4ca..8d54a96 100644
--- a/pi-slate/extensions/pi-slate/sidebar-data.ts
+++ b/pi-slate/extensions/pi-slate/sidebar-data.ts
@@ -13,7 +13,8 @@ export type SidebarSkill = { name: string; path: string; source: string; loaded:
 export type SidebarCommand = { name: string; source: string; description?: string };
 export type SidebarPrompt = { name: string; source: string; description?: string };
 export type SidebarMcp = { name: string; enabled: boolean | null; source: string };
-export type SidebarResources = { skills: SidebarSkill[]; commands: SidebarCommand[]; prompts: SidebarPrompt[]; mcp: SidebarMcp[]; mcpError?: string };
+export type SidebarMcpResult = { mcp: SidebarMcp[]; mcpError?: string; mcpWarning?: string };
+export type SidebarResources = { skills: SidebarSkill[]; commands: SidebarCommand[]; prompts: SidebarPrompt[] } & SidebarMcpResult;
 export type SidebarSession = {
   id: string; name?: string; pid: number; cwd: string; model: string; thinking: string;
   tokens: number | null; percent: number | null; contextWindow: number | null;
@@ -208,7 +209,7 @@ export function sidebarMcp(
 
 function resolveMcp(
   registered: readonly { name: string; config: unknown }[], global: McpFile, project: McpFile | undefined, host: SidebarMcpHost | undefined,
-): { mcp: SidebarMcp[]; mcpError?: string } {
+): SidebarMcpResult {
   const files = new Map<string, { config: Record<string, unknown>; source: string }>();
   const invalid = new Map<string, SidebarMcp>();
   let rejected = false;
@@ -242,8 +243,11 @@ function resolveMcp(
   }
   for (const [name, server] of files) rows.set(name, { name: sidebarText(name), source: server.source, enabled: server.config.enabled !== false });
   for (const [name, row] of invalid) if (!rows.has(name)) rows.set(name, row);
+  // File errors take precedence; a missing adapter may still warn alongside them.
+  const mcpError = project?.error ?? global.error ?? (rejected ? "MCP configuration has rejected entries" : undefined);
+  const mcpWarning = !host && rows.size > 0 ? "MCP configuration validation unavailable" : undefined;
   return { mcp: [...rows.values()].sort((a, b) => a.name.localeCompare(b.name)),
-    ...(!host && rows.size > 0 ? { mcpError: "MCP configuration validation unavailable" } : rejected ? { mcpError: "MCP configuration has rejected entries" } : {}) };
+    ...(mcpError ? { mcpError } : {}), ...(mcpWarning ? { mcpWarning } : {}) };
 }
 
 /** File reads are bounded and cached outside render; never evaluate env or credential commands. */
@@ -269,12 +273,10 @@ export class SidebarMcpFiles {
       return (error as NodeJS.ErrnoException).code === "ENOENT" ? { servers: {} } : { servers: {}, error: "MCP config unreadable" };
     }
   }
-  snapshot(agentDir: string, cwd: string, trusted: boolean, registered: readonly { name: string; config: unknown }[]): { mcp: SidebarMcp[]; mcpError?: string } {
+  snapshot(agentDir: string, cwd: string, trusted: boolean, registered: readonly { name: string; config: unknown }[]): SidebarMcpResult {
     const global = this.read(join(agentDir, "mcp.json"));
     const project = trusted ? this.read(join(cwd, ".pi", "mcp.json")) : undefined;
-    const result = resolveMcp(registered, global, project, this.host);
-    const error = project?.error ?? global.error ?? result.mcpError;
-    return { mcp: result.mcp, ...(error ? { mcpError: error } : {}) };
+    return resolveMcp(registered, global, project, this.host);
   }
   clear(): void { this.cached.clear(); }
 }
diff --git a/pi-slate/extensions/pi-slate/sidebar-mcp.ts b/pi-slate/extensions/pi-slate/sidebar-mcp.ts
index 7e826c8..dbb70cf 100644
--- a/pi-slate/extensions/pi-slate/sidebar-mcp.ts
+++ b/pi-slate/extensions/pi-slate/sidebar-mcp.ts
@@ -9,27 +9,25 @@ export type SidebarMcpHost = {
   stripBom: boolean;
 };
 
-// Verified against native file parsers; unknown formats still fail closed.
-const HOST_FORMATS = new Map([
-  ["0.99.0", { projectOverrides: false, stripBom: false }],
-  ["1.0.0", { projectOverrides: false, stripBom: false }],
-  ["1.1.0", { projectOverrides: true, stripBom: false }],
-  ["1.3.0", { projectOverrides: true, stripBom: false }],
-  ["1.4.0", { projectOverrides: true, stripBom: true }],
-]);
+/** Version only selects legacy parsing exceptions; capabilities determine availability. */
+function hostParsing(version: string): { projectOverrides: boolean; stripBom: boolean } {
+  if (version === "0.99.0" || version === "1.0.0") return { projectOverrides: false, stripBom: false };
+  const release = /^1\.(\d+)\.(\d+)$/.exec(version);
+  const minor = release ? Number(release[1]) : Number.NaN;
+  const patch = release ? Number(release[2]) : Number.NaN;
+  // 1.0.4+ and the released 1.1–1.3 minors merge project overrides and reject a BOM. 1.4+ strips it.
+  if ((minor === 0 && patch >= 4) || (minor >= 1 && minor < 4)) return { projectOverrides: true, stripBom: false };
+  return { projectOverrides: true, stripBom: true };
+}
 
 export async function loadSidebarMcpHost(packageDir: string, version: string): Promise<SidebarMcpHost | undefined> {
   try {
-    const patch = /^1\.0\.(\d+)$/.exec(version);
-    const format = HOST_FORMATS.get(version)
-      ?? (patch !== null && Number(patch[1]) >= 4 ? { projectOverrides: true, stripBom: false } : undefined);
-    if (!format) return undefined;
+    const { projectOverrides, stripBom } = hostParsing(version);
     const native = await import(pathToFileURL(join(packageDir, "dist/core/mcp-servers.js")).href) as {
       validateMcpServerConfig?: SidebarMcpHost["validate"];
       mcpNamespace?: SidebarMcpHost["namespace"];
     };
     if (typeof native.validateMcpServerConfig !== "function") return undefined;
-    const { projectOverrides, stripBom } = format;
     if (projectOverrides && typeof native.mcpNamespace !== "function") return undefined;
     return { validate: native.validateMcpServerConfig,
       namespace: projectOverrides ? native.mcpNamespace! : name => name, projectOverrides, stripBom };
diff --git a/pi-slate/extensions/pi-slate/sidebar.ts b/pi-slate/extensions/pi-slate/sidebar.ts
index 23660e2..6b50d1f 100644
--- a/pi-slate/extensions/pi-slate/sidebar.ts
+++ b/pi-slate/extensions/pi-slate/sidebar.ts
@@ -275,17 +275,19 @@ export class Sidebar implements Component {
   }
   private middle(): Row[] {
     const enabled = this.resources.mcp.filter(x => x.enabled === true).length;
-    const unknown = this.resources.mcp.some(x => x.enabled === null);
-    const rejected = this.resources.mcp.filter(x => x.enabled === null).length;
+    const unknownCount = this.resources.mcp.filter(x => x.enabled === null).length;
     const errors = this.resources.mcpError
-      ? (this.resources.mcpError === "MCP configuration has rejected entries" && rejected > 0 ? rejected : 1)
+      ? (this.resources.mcpError === "MCP configuration has rejected entries" && unknownCount > 0 ? unknownCount : 1)
       : 0;
+    const allUnknown = unknownCount > 0 && unknownCount === this.resources.mcp.length;
+    const warning = !errors && Boolean(this.resources.mcpWarning);
     const loaded = this.resources.skills.filter(x => x.loaded).length;
-    const resourceHeading = (label: string, count: string, failed = 0): string =>
+    const resourceHeading = (label: string, count: string, failed = 0, warned = false): string =>
       this.heading(label) + this.paint("muted", ` · ${count}`)
-      + (failed ? this.paint("error", ` · ${failed} ${failed === 1 ? "Error" : "Errors"}`) : "");
+      + (failed ? this.paint("error", ` · ${failed} ${failed === 1 ? "Error" : "Errors"}`) : "")
+      + (warned ? this.paint("warning", " · 1 Warning") : "");
     const rows: Row[] = [{ text: "" }, {
-      text: resourceHeading(`${this.folds.mcp ? "⌄" : "›"} MCP`, errors || !unknown ? `${enabled} Enabled` : "—", errors),
+      text: resourceHeading(`${this.folds.mcp ? "⌄" : "›"} MCP`, allUnknown || (!errors && unknownCount > 0) ? "—" : `${enabled} Enabled`, errors, warning),
       action: () => this.toggleSection("mcp"),
     }];
     if (this.folds.mcp) rows.push(...this.resourceRows("mcp"));
@@ -306,8 +308,9 @@ export class Sidebar implements Component {
       if (list === "mcp") {
         const server = this.resources.mcp[i]!;
         const state = server.enabled === null ? "—" : server.enabled ? "enabled" : "disabled";
+        const validationWarning = !this.resources.mcpError && server.enabled === null ? this.resources.mcpWarning : undefined;
         rows.push({ text: this.paint(server.enabled === null ? "warning" : server.enabled ? "muted" : "dim", `${server.enabled === null ? "—" : server.enabled ? "●" : "○"} ${sidebarText(server.name)}`), list, item: i,
-          action: () => this.actions?.inspect?.(server.name, `${state} (configuration, not connection status)\nSource: ${server.source}\nUse /mcp to manage this server.`) });
+          action: () => this.actions?.inspect?.(server.name, `${state} (configuration, not connection status)\nSource: ${server.source}${validationWarning ? `\n${validationWarning}` : ""}\nUse /mcp to manage this server.`) });
       } else if (list === "skills") {
         const skill = this.resources.skills[i]!;
         rows.push({ text: this.paint(skill.loaded ? "muted" : "dim", `${skill.loaded ? "●" : "○"} ${sidebarText(skill.name)}`), list, item: i,
diff --git a/pi-slate/tests/sidebar-mcp.test.ts b/pi-slate/tests/sidebar-mcp.test.ts
index 92359a7..513d6f8 100644
--- a/pi-slate/tests/sidebar-mcp.test.ts
+++ b/pi-slate/tests/sidebar-mcp.test.ts
@@ -31,6 +31,7 @@ for (const [packageDir, version] of packages) {
       [{ x: { url: "https://example.com", headers: { token: 123 } }, y: { url: "https://example.com", oauth: { callbackPort: -1, clientSecret: "SECRET" } } }, {}],
       [{}, { x: { url: "https://example.com", auth: { provider: "fixture" } } }],
       [{ x: { command: "server", enabled: false, exposure: "codemode-deferred" } }, {}],
+      [{ auto: { url: "https://example.com/mcp", oauth: { clientRegistration: "auto" } } }, {}],
     ];
     for (const [global, project] of fixtures) {
       await writeFile(join(agentDir, "mcp.json"), JSON.stringify({ mcpServers: global }));
@@ -41,6 +42,7 @@ for (const [packageDir, version] of packages) {
       const configured = new Set([...Object.keys(global), ...Object.keys(project)]);
       const nativeRows = loaded.servers.filter(row => configured.has(row.name)).map(row => [row.name, row.config.enabled !== false]).sort();
       assert.equal(Boolean(result.mcpError), loaded.errors.length > 0);
+      assert.equal(result.mcpWarning, undefined);
       assert.deepEqual(
         result.mcp.filter(row => row.enabled !== null && configured.has(row.name)).map(row => [row.name, row.enabled]).sort(),
         nativeRows,
@@ -59,33 +61,53 @@ for (const [packageDir, version] of packages) {
     await writeFile(join(agentDir, "mcp.json"), '{"mcpServers":{}}');
     await writeFile(join(cwd, ".pi/mcp.json"), '{"mcpServers":{"registered":{"enabled":false}}}'); cache.clear();
     assert.equal(cache.snapshot(agentDir, cwd, true, [{ name: "registered", config: { command: "server" } }]).mcp[0]!.enabled, true);
+    await writeFile(join(agentDir, "mcp.json"), JSON.stringify({ mcpServers: { auto: { url: "https://example.com/mcp", oauth: { clientRegistration: "auto" } } } }));
+    await writeFile(join(cwd, ".pi/mcp.json"), '{"mcpServers":{}}'); cache.clear();
+    const autoLoaded = native.loadMcpConfig({ agentDir, cwd, projectTrusted: true });
+    const autoResult = cache.snapshot(agentDir, cwd, true, []);
+    const autoEnabled = autoResult.mcp.find(row => row.name === "auto")?.enabled ?? null;
+    assert.equal(autoEnabled === true, autoLoaded.servers.some(row => row.name === "auto"), `${version} uses the running native validator`);
+    assert.equal(Boolean(autoResult.mcpError), autoLoaded.errors.length > 0);
+    assert.equal(autoResult.mcpWarning, undefined);
+    if (version === "1.4.0") assert.equal(autoEnabled, null, "Pi 1.4 rejects oauth.clientRegistration auto");
+    if (version === "1.5.0") assert.equal(autoEnabled, true, "Pi 1.5 accepts oauth.clientRegistration auto");
   });
 }
 test("host adapter requires native validation and modern namespaces", async t => {
   const root = await mkdtemp(join(tmpdir(), "slate-mcp-exports-")); t.after(() => rm(root, { recursive: true, force: true }));
   const fixtures = [
-    { name: "missing-validator", exports: 'export const mcpNamespace = name => name;', modern: false, legacy: false },
-    { name: "invalid-validator", exports: 'export const validateMcpServerConfig = true; export const mcpNamespace = name => name;', modern: false, legacy: false },
-    { name: "missing-namespace", exports: 'export const validateMcpServerConfig = (_name, value) => value;', modern: false, legacy: true },
-    { name: "invalid-namespace", exports: 'export const validateMcpServerConfig = (_name, value) => value; export const mcpNamespace = true;', modern: false, legacy: true },
-    { name: "complete", exports: 'export const validateMcpServerConfig = (_name, value) => value; export const mcpNamespace = name => name;', modern: true, legacy: true },
+    { name: "missing-validator", exports: "export const mcpNamespace = name => name;", modern: false, legacy: false },
+    { name: "invalid-validator", exports: "export const validateMcpServerConfig = true; export const mcpNamespace = name => name;", modern: false, legacy: false },
+    { name: "missing-namespace", exports: "export const validateMcpServerConfig = (_name, value) => value;", modern: false, legacy: true },
+    { name: "invalid-namespace", exports: "export const validateMcpServerConfig = (_name, value) => value; export const mcpNamespace = true;", modern: false, legacy: true },
+    { name: "complete", exports: "export const validateMcpServerConfig = (_name, value) => value; export const mcpNamespace = name => name;", modern: true, legacy: true },
+    { name: "throws", exports: "throw new Error(\"load failed\");", modern: false, legacy: false },
   ];
+  const modernVersions = ["1.1.0", "1.4.0", "2.0.0", "not-a-version"];
   for (const fixture of fixtures) {
     const packageDir = join(root, fixture.name);
     await mkdir(join(packageDir, "dist/core"), { recursive: true });
     await writeFile(join(packageDir, "package.json"), '{"type":"module"}');
     await writeFile(join(packageDir, "dist/core/mcp-servers.js"), fixture.exports);
-    assert.equal(Boolean(await loadSidebarMcpHost(packageDir, "1.4.0")), fixture.modern, fixture.name);
+    for (const version of modernVersions) {
+      assert.equal(Boolean(await loadSidebarMcpHost(packageDir, version)), fixture.modern, `${fixture.name}@${version}`);
+    }
+    assert.equal(Boolean(await loadSidebarMcpHost(packageDir, "0.99.0")), fixture.legacy, fixture.name);
     assert.equal(Boolean(await loadSidebarMcpHost(packageDir, "1.0.0")), fixture.legacy, fixture.name);
   }
   for (const [version, projectOverrides, stripBom] of [
-    ["0.99.0", false, false], ["1.0.0", false, false], ["1.0.4", true, false],
-    ["1.0.99", true, false], ["1.1.0", true, false], ["1.3.0", true, false], ["1.4.0", true, true],
+    ["0.99.0", false, false], ["1.0.0", false, false], ["1.0.3", true, true], ["1.0.4", true, false],
+    ["1.0.99", true, false], ["1.1.0", true, false], ["1.2.0", true, false], ["1.3.0", true, false],
+    ["1.3.1", true, false], ["1.4.0", true, true], ["1.4.1", true, true], ["1.5.0", true, true],
+    ["1.5.1", true, true], ["1.10.0", true, true], ["2.0.0", true, true], ["9.1.0", true, true],
+    ["unknown", true, true], ["1.5.0-rc.1", true, true], ["", true, true],
   ] as const) {
     const host = await loadSidebarMcpHost(join(root, "complete"), version); assert(host, version);
     assert.equal(host.projectOverrides, projectOverrides, version);
     assert.equal(host.stripBom, stripBom, version);
   }
+  assert.equal(await loadSidebarMcpHost(join(root, "absent"), "1.5.0"), undefined);
+  assert.equal(await loadSidebarMcpHost(join(root, "absent"), "not-a-version"), undefined);
 });
 
 test("unavailable validation is not an error without entries, but file errors remain visible", async t => {
@@ -93,28 +115,43 @@ test("unavailable validation is not an error without entries, but file errors re
   await mkdir(join(root, ".pi"));
   const cache = new SidebarMcpFiles();
   assert.deepEqual(cache.snapshot(root, root, true, []), { mcp: [] }, "missing files need no validation");
-  await writeFile(join(root, "mcp.json"), '{}');
+  await writeFile(join(root, "mcp.json"), "{}");
   await writeFile(join(root, ".pi/mcp.json"), '{"mcpServers":{}}');
   assert.deepEqual(cache.snapshot(root, root, true, []), { mcp: [] }, "empty files need no validation");
   await writeFile(join(root, ".pi/mcp.json"), '{"mcpServers":{"project":{"command":"server"}}}');
   assert.deepEqual(cache.snapshot(root, root, false, []), { mcp: [] }, "untrusted entries are not read");
   const project = cache.snapshot(root, root, true, []);
-  assert.equal(project.mcp[0]!.enabled, null); assert.match(project.mcpError!, /unavailable/);
-  await writeFile(join(root, ".pi/mcp.json"), '{bad');
-  assert.equal(cache.snapshot(root, root, true, []).mcpError, "MCP config unreadable");
+  assert.equal(project.mcp[0]!.enabled, null);
+  assert.equal(project.mcpError, undefined);
+  assert.match(project.mcpWarning!, /unavailable/);
+  await writeFile(join(root, ".pi/mcp.json"), "{bad");
+  const unreadable = cache.snapshot(root, root, true, []);
+  assert.equal(unreadable.mcpError, "MCP config unreadable");
+  assert.equal(unreadable.mcpWarning, undefined);
   await writeFile(join(root, "mcp.json"), '{"mcpServers":[]}');
-  assert.equal(cache.snapshot(root, root, false, []).mcpError, "MCP config invalid");
+  const invalid = cache.snapshot(root, root, false, []);
+  assert.equal(invalid.mcpError, "MCP config invalid");
+  assert.equal(invalid.mcpWarning, undefined);
   await writeFile(join(root, "mcp.json"), '{"mcpServers":{"global":{"command":"server"}}}');
   const global = cache.snapshot(root, root, false, []);
-  assert.equal(global.mcp[0]!.enabled, null); assert.match(global.mcpError!, /unavailable/);
+  assert.equal(global.mcp[0]!.enabled, null);
+  assert.equal(global.mcpError, undefined);
+  assert.match(global.mcpWarning!, /unavailable/);
+  await writeFile(join(root, "mcp.json"), "{bad");
+  const fileAndAdapter = cache.snapshot(root, root, false, [{ name: "registered", config: { command: "server", env: { TOKEN: "SECRET" } } }]);
+  assert.equal(fileAndAdapter.mcpError, "MCP config unreadable");
+  assert.match(fileAndAdapter.mcpWarning!, /unavailable/);
+  assert.equal(fileAndAdapter.mcp.find(row => row.name === "registered")?.enabled, null);
+  assert(!JSON.stringify(fileAndAdapter).includes("SECRET"));
 });
 
 test("unavailable host adapter never fabricates enabled/disabled state", async () => {
-  assert.equal(await loadSidebarMcpHost("/missing", "1.4.0"), undefined);
-  for (const version of ["unknown", "1.2.0", "1.4.1", "2.0.0"]) {
-    assert.equal(await loadSidebarMcpHost(getPackageDir(), version), undefined);
-  }
+  assert.equal(await loadSidebarMcpHost("/missing", "1.5.0"), undefined);
+  assert.equal(await loadSidebarMcpHost("/missing", "2.0.0"), undefined);
   const cache = new SidebarMcpFiles();
   const result = cache.snapshot("/missing", "/missing", false, [{ name: "registered", config: { command: "server" } }]);
-  assert.equal(result.mcp[0]!.enabled, null); assert.match(result.mcpError!, /unavailable/);
+  assert.equal(result.mcp[0]!.enabled, null);
+  assert.equal(result.mcpError, undefined);
+  assert.match(result.mcpWarning!, /unavailable/);
+  assert.deepEqual(cache.snapshot("/missing", "/missing", false, []), { mcp: [] });
 });
diff --git a/pi-slate/tests/sidebar-preview.test.ts b/pi-slate/tests/sidebar-preview.test.ts
index 35405d2..01b4892 100644
--- a/pi-slate/tests/sidebar-preview.test.ts
+++ b/pi-slate/tests/sidebar-preview.test.ts
@@ -1,9 +1,12 @@
 import assert from "node:assert/strict";
+import { mkdtemp, rm, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
 import test from "node:test";
 import type { Theme } from "@earendil-works/pi-coding-agent";
 import { visibleWidth, type TUI, type TuiMouseEvent } from "@earendil-works/pi-tui";
 import { Sidebar, DOUBLE_CLICK_MS } from "../extensions/pi-slate/sidebar.ts";
-import type { SidebarResources, SidebarSession } from "../extensions/pi-slate/sidebar-data.ts";
+import { SidebarMcpFiles, type SidebarResources, type SidebarSession } from "../extensions/pi-slate/sidebar-data.ts";
 import { sessionSidebarSlots } from "../extensions/pi-slate/sidebar-layout.ts";
 import { DiffWorkspaceView, type WorkspaceView } from "../extensions/pi-slate/workspace.ts";
 import type { BackgroundTask } from "../extensions/pi-slate/background-tasks.ts";
@@ -443,6 +446,64 @@ test("rejected MCP entries count as Errors without dumping the reason", () => {
   assert(!lines.some(line => line.includes("rejected entries") || line.includes("config error")));
 });
 
+test("unavailable MCP validation renders as a warning when folded or expanded", () => {
+  const { sidebar } = fixture();
+  const details: string[] = [];
+  sidebar.setActions({ copy() {}, openFile() {}, inspect: (_title, text) => details.push(text) });
+  sidebar.setResources({
+    ...resources,
+    mcp: [{ name: "unknown-server", enabled: null, source: "global" }],
+    mcpWarning: "MCP configuration validation unavailable",
+  });
+  const folded = plain(sidebar.render(80));
+  assert(folded.some(line => line.includes("› MCP · — · 1 Warning")));
+  assert(!folded.some(line => line.includes("Error") || line.includes("0 Enabled") || line.includes("validation unavailable")));
+  sidebar.setFolds({ mcp: true, skills: false, prompts: false });
+  const expanded = plain(sidebar.render(80));
+  assert(expanded.some(line => line.includes("⌄ MCP · — · 1 Warning")));
+  assert(expanded.some(line => line.trim() === "— unknown-server"));
+  assert(!expanded.some(line => line.includes("Error") || line.includes("0 Enabled") || line.includes("validation unavailable")));
+  sidebar.setThemeProvider(() => ({ fg: (tone: string, text: string) => tone === "warning" ? `\x1b[33m${text}\x1b[0m` : tone === "error" ? `\x1b[31m${text}\x1b[0m` : text, bold: (text: string) => text }) as Theme);
+  const painted = sidebar.render(80).join("\n");
+  assert(painted.includes("\x1b[33m · 1 Warning\x1b[0m"));
+  assert(!painted.includes("\x1b[31m"));
+  sidebar.handleMouse(mouse(row(sidebar, "unknown-server")));
+  assert.match(details[0]!, /MCP configuration validation unavailable/);
+  assert(!details[0]!.includes("SECRET"));
+});
+
+test("MCP file errors stay numeric and outrank a validation warning", () => {
+  const { sidebar } = fixture();
+  sidebar.setResources({ ...resources, mcpError: "MCP config unreadable", mcpWarning: "MCP configuration validation unavailable" });
+  const mixed = plain(sidebar.render(80));
+  assert(mixed.some(line => line.includes("MCP · 6 Enabled · 1 Error")));
+  assert(!mixed.some(line => line.includes("Warning") || line.includes("validation unavailable")));
+  sidebar.setResources({
+    skills: [], commands: [], prompts: [],
+    mcp: [{ name: "bad", enabled: null, source: "global" }],
+    mcpError: "MCP config unreadable",
+    mcpWarning: "MCP configuration validation unavailable",
+  });
+  const unknown = plain(sidebar.render(80));
+  assert(unknown.some(line => line.includes("MCP · — · 1 Error")));
+  assert(!unknown.some(line => line.includes("0 Enabled") || line.includes("Warning")));
+});
+
+test("a missing MCP host snapshot renders a warning instead of a config error", async t => {
+  const root = await mkdtemp(join(tmpdir(), "slate-mcp-warning-"));
+  t.after(() => rm(root, { recursive: true, force: true }));
+  await writeFile(join(root, "mcp.json"), JSON.stringify({ mcpServers: { docs: { command: "server" } } }));
+  const snapshot = new SidebarMcpFiles().snapshot(root, root, false, []);
+  const { sidebar } = fixture();
+  sidebar.setResources({ skills: [], commands: [], prompts: [], ...snapshot });
+  const lines = plain(sidebar.render(80));
+  assert.equal(snapshot.mcpError, undefined);
+  assert.equal(snapshot.mcp[0]!.enabled, null);
+  assert.match(snapshot.mcpWarning!, /unavailable/);
+  assert(lines.some(line => line.includes("MCP · — · 1 Warning")));
+  assert(!lines.some(line => line.includes("Error") || line.includes("0 Enabled") || line.includes("validation unavailable")));
+});
+
 test("reset discards old titles, images, task rows and hit targets without changing fold preference", () => {
   const { sidebar } = fixture();
   const copied: string[] = [];