diff --git a/packages/opencode/src/cli/cmd/mcp.ts b/packages/opencode/src/cli/cmd/mcp.ts
index 2ae7cece6a2..81fb627187e 100644
--- a/packages/opencode/src/cli/cmd/mcp.ts
+++ b/packages/opencode/src/cli/cmd/mcp.ts
@@ -271,6 +271,9 @@ export const McpAuthCommand = effectCmd({
         Effect.sync(() => {
           if (status.status === "connected") {
             spinner.stop("Authentication successful!")
+          } else if (status.status === "needs_auth") {
+            spinner.stop("Authentication did not complete", 1)
+            prompts.log.error("Server connected without storing OAuth credentials")
           } else if (status.status === "needs_client_registration") {
             spinner.stop("Authentication failed", 1)
             prompts.log.error(status.error)
diff --git a/packages/opencode/src/mcp/auth.ts b/packages/opencode/src/mcp/auth.ts
index be19be0af04..b67c1f9087c 100644
--- a/packages/opencode/src/mcp/auth.ts
+++ b/packages/opencode/src/mcp/auth.ts
@@ -33,6 +33,11 @@ type AuthData = Record<string, Entry>
 
 const filepath = path.join(Global.Path.data, "mcp-auth.json")
 
+function normalizeEntry(entry: Entry | undefined) {
+  if (!entry) return
+  if (entry.tokens || entry.clientInfo || entry.codeVerifier || entry.oauthState) return entry
+}
+
 export interface Interface {
   readonly all: () => Effect.Effect<Record<string, Entry>>
   readonly get: (mcpName: string) => Effect.Effect<Entry | undefined>
@@ -58,7 +63,12 @@ export const layer = Layer.effect(
 
     const all = Effect.fn("McpAuth.all")(function* () {
       return yield* fs.readJson(filepath).pipe(
-        Effect.map((data): AuthData => Option.getOrElse(decodeAuthData(data), () => ({}) as AuthData) as AuthData),
+        Effect.map((data): AuthData => {
+          const decoded = Option.getOrElse(decodeAuthData(data), () => ({}) as AuthData) as AuthData
+          return Object.fromEntries(
+            Object.entries(decoded).flatMap(([mcpName, entry]) => (normalizeEntry(entry) ? [[mcpName, entry]] : [])),
+          )
+        }),
         Effect.catch(() => Effect.succeed({} as AuthData)),
       )
     })
@@ -78,8 +88,13 @@ export const layer = Layer.effect(
 
     const set = Effect.fn("McpAuth.set")(function* (mcpName: string, entry: Entry, serverUrl?: string) {
       const data = yield* all()
-      if (serverUrl) entry.serverUrl = serverUrl
-      yield* fs.writeJson(filepath, { ...data, [mcpName]: entry }, 0o600).pipe(Effect.orDie)
+      const next = normalizeEntry(serverUrl ? { ...entry, serverUrl } : entry)
+      if (!next) {
+        delete data[mcpName]
+        yield* fs.writeJson(filepath, data, 0o600).pipe(Effect.orDie)
+        return
+      }
+      yield* fs.writeJson(filepath, { ...data, [mcpName]: next }, 0o600).pipe(Effect.orDie)
     })
 
     const remove = Effect.fn("McpAuth.remove")(function* (mcpName: string) {
diff --git a/packages/opencode/src/mcp/index.ts b/packages/opencode/src/mcp/index.ts
index 832811b281a..878bde476f2 100644
--- a/packages/opencode/src/mcp/index.ts
+++ b/packages/opencode/src/mcp/index.ts
@@ -3,7 +3,8 @@ import { Client } from "@modelcontextprotocol/sdk/client/index.js"
 import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js"
 import { SSEClientTransport } from "@modelcontextprotocol/sdk/client/sse.js"
 import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js"
-import { UnauthorizedError } from "@modelcontextprotocol/sdk/client/auth.js"
+import { auth as performOAuth, UnauthorizedError } from "@modelcontextprotocol/sdk/client/auth.js"
+import { createFetchWithInit } from "@modelcontextprotocol/sdk/shared/transport.js"
 import {
   CallToolResultSchema,
   ListToolsResultSchema,
@@ -756,7 +757,7 @@ export const layer = Layer.effect(
       return mcpConfig
     })
 
-    const startAuth = Effect.fn("MCP.startAuth")(function* (mcpName: string) {
+    const beginAuth = Effect.fn("MCP.beginAuth")(function* (mcpName: string) {
       const mcpConfig = yield* getMcpConfig(mcpName)
       if (!mcpConfig) throw new Error(`MCP server ${mcpName} not found or disabled`)
       if (mcpConfig.type !== "remote") throw new Error(`MCP server ${mcpName} is not a remote server`)
@@ -792,7 +793,24 @@ export const layer = Layer.effect(
         auth,
       )
 
-      const transport = new StreamableHTTPClientTransport(url, { authProvider })
+      const requestInit = mcpConfig.headers ? { headers: mcpConfig.headers } : undefined
+      const transport = new StreamableHTTPClientTransport(url, { authProvider, requestInit })
+
+      const authorization = yield* Effect.tryPromise({
+        try: () =>
+          performOAuth(authProvider, {
+            serverUrl: url,
+            scope: oauthConfig?.scope,
+            fetchFn: createFetchWithInit(undefined, requestInit),
+          }),
+        catch: (error) => (error instanceof Error ? error : new Error(String(error))),
+      })
+
+      if (authorization === "REDIRECT") {
+        if (!capturedUrl) throw new Error(`OAuth redirect requested without authorization URL for MCP server: ${mcpName}`)
+        pendingOAuthTransports.set(mcpName, transport)
+        return { authorizationUrl: capturedUrl.toString(), oauthState } satisfies AuthResult
+      }
 
       return yield* Effect.tryPromise({
         try: () => {
@@ -802,19 +820,11 @@ export const layer = Layer.effect(
             .then(() => ({ authorizationUrl: "", oauthState, client }) satisfies AuthResult)
         },
         catch: (error) => error,
-      }).pipe(
-        Effect.catch((error) => {
-          if (error instanceof UnauthorizedError && capturedUrl) {
-            pendingOAuthTransports.set(mcpName, transport)
-            return Effect.succeed({ authorizationUrl: capturedUrl.toString(), oauthState } satisfies AuthResult)
-          }
-          return Effect.die(error)
-        }),
-      )
+      })
     })
 
-    const authenticate = Effect.fn("MCP.authenticate")(function* (mcpName: string) {
-      const result = yield* startAuth(mcpName)
+    const authenticateImpl = Effect.fn("MCP.authenticate")(function* (mcpName: string) {
+      const result = yield* beginAuth(mcpName)
       if (!result.authorizationUrl) {
         const client = "client" in result ? result.client : undefined
         const mcpConfig = yield* getMcpConfig(mcpName)
@@ -829,8 +839,19 @@ export const layer = Layer.effect(
           return { status: "failed", error: "Failed to get tools" } as Status
         }
 
-        const s = yield* InstanceState.get(state)
         yield* auth.clearOAuthState(mcpName)
+        yield* auth.clearCodeVerifier(mcpName)
+        const authStatus = yield* getAuthStatus(mcpName)
+        if (authStatus !== "authenticated") {
+          log.warn("oauth authenticate completed without stored tokens", { mcpName, authStatus })
+          yield* Effect.tryPromise(() => client.close()).pipe(Effect.ignore)
+          return {
+            status: "failed",
+            error: "Server connected without requesting OAuth. This MCP endpoint may not support interactive OAuth authentication.",
+          } as Status
+        }
+
+        const s = yield* InstanceState.get(state)
         return yield* storeClient(s, mcpName, client, listed, mcpConfig.timeout)
       }
 
@@ -871,6 +892,14 @@ export const layer = Layer.effect(
       return yield* finishAuth(mcpName, code)
     })
 
+    const startAuth = (mcpName: string) =>
+      beginAuth(mcpName).pipe(
+        Effect.map((result) => ({ authorizationUrl: result.authorizationUrl, oauthState: result.oauthState })),
+        Effect.orDie,
+      )
+
+    const authenticate = (mcpName: string) => authenticateImpl(mcpName).pipe(Effect.orDie)
+
     const finishAuth = Effect.fn("MCP.finishAuth")(function* (mcpName: string, authorizationCode: string) {
       const transport = pendingOAuthTransports.get(mcpName)
       if (!transport) throw new Error(`No pending OAuth flow for MCP server: ${mcpName}`)
diff --git a/packages/opencode/test/mcp/lifecycle.test.ts b/packages/opencode/test/mcp/lifecycle.test.ts
index 185086fe60a..fa0db99864c 100644
--- a/packages/opencode/test/mcp/lifecycle.test.ts
+++ b/packages/opencode/test/mcp/lifecycle.test.ts
@@ -110,6 +110,7 @@ void mock.module("@modelcontextprotocol/sdk/client/auth.js", () => ({
       super("Unauthorized")
     }
   },
+  auth: async () => "AUTHORIZED",
 }))
 
 // Mock Client that delegates to per-name MockClientState
diff --git a/packages/opencode/test/mcp/oauth-auto-connect.test.ts b/packages/opencode/test/mcp/oauth-auto-connect.test.ts
index 6fb15c45947..e7ac56430c4 100644
--- a/packages/opencode/test/mcp/oauth-auto-connect.test.ts
+++ b/packages/opencode/test/mcp/oauth-auto-connect.test.ts
@@ -21,6 +21,7 @@ const transportCalls: Array<{
 // auth flow (which calls provider.state()) or a simple UnauthorizedError.
 let simulateAuthFlow = true
 let connectSucceedsImmediately = false
+let directAuthResult: "REDIRECT" | "AUTHORIZED" = "REDIRECT"
 
 // Mock the transport constructors to simulate OAuth auto-auth on 401
 void mock.module("@modelcontextprotocol/sdk/client/streamableHttp.js", () => ({
@@ -102,12 +103,26 @@ void mock.module("@modelcontextprotocol/sdk/client/index.js", () => ({
 // Mock UnauthorizedError in the auth module so instanceof checks work
 void mock.module("@modelcontextprotocol/sdk/client/auth.js", () => ({
   UnauthorizedError: MockUnauthorizedError,
+  auth: async (
+    provider: {
+      state?: () => Promise<string>
+      saveCodeVerifier?: (v: string) => Promise<void>
+      redirectToAuthorization?: (url: URL) => Promise<void>
+    },
+  ) => {
+    if (directAuthResult === "AUTHORIZED") return "AUTHORIZED"
+    await provider.state?.()
+    await provider.saveCodeVerifier?.("test-verifier")
+    await provider.redirectToAuthorization?.(new URL("https://auth.example.com/authorize?state=test"))
+    return "REDIRECT"
+  },
 }))
 
 beforeEach(() => {
   transportCalls.length = 0
   simulateAuthFlow = true
   connectSucceedsImmediately = false
+  directAuthResult = "REDIRECT"
 })
 
 // Import modules after mocking
@@ -210,11 +225,39 @@ mcpTest.instance("state() returns existing state when one is saved", () =>
   }),
 )
 
+mcpTest.instance("invalidateCredentials() removes entries that only retain serverUrl", () =>
+  Effect.gen(function* () {
+    const auth = yield* McpAuth.Service
+    const provider = new McpOAuthProvider(
+      "test-stale-server-url",
+      "https://example.com/mcp",
+      {},
+      { onRedirect: async () => {} },
+      auth,
+    )
+
+    yield* Effect.promise(() =>
+      provider.saveTokens({
+        access_token: "token",
+        token_type: "Bearer",
+      }),
+    )
+
+    expect((yield* auth.get("test-stale-server-url"))?.serverUrl).toBe("https://example.com/mcp")
+
+    yield* Effect.promise(() => provider.invalidateCredentials("tokens"))
+
+    expect(yield* auth.get("test-stale-server-url")).toBeUndefined()
+    expect((yield* auth.all())["test-stale-server-url"]).toBeUndefined()
+  }),
+)
+
 mcpTest.instance(
-  "authenticate() stores a connected client when auth completes without redirect",
+  "authenticate() fails clearly when transport reconnects without stored tokens",
   () =>
     MCP.Service.use((mcp) =>
       Effect.gen(function* () {
+        const auth = yield* McpAuth.Service
         const added = yield* mcp.add("test-oauth-connect", {
           type: "remote",
           url: "https://example.com/mcp",
@@ -222,15 +265,39 @@ mcpTest.instance(
         const before = added.status as Record<string, { status: string; error?: string }>
         expect(before["test-oauth-connect"]?.status).toBe("needs_auth")
 
+        directAuthResult = "AUTHORIZED"
         simulateAuthFlow = false
         connectSucceedsImmediately = true
 
         const result = yield* mcp.authenticate("test-oauth-connect")
-        expect(result.status).toBe("connected")
+        expect(result.status).toBe("failed")
+        if (result.status === "failed") {
+          expect(result.error).toContain("may not support interactive OAuth authentication")
+        }
+
+        const entry = yield* auth.get("test-oauth-connect")
+        expect(entry).toBeUndefined()
 
         const after = yield* mcp.status()
-        expect(after["test-oauth-connect"]?.status).toBe("connected")
+        expect(after["test-oauth-connect"]?.status).toBe("needs_auth")
       }),
     ),
   { config: config("test-oauth-connect") },
 )
+
+mcpTest.instance(
+  "startAuth() returns an authorization URL even when transport can connect anonymously",
+  () =>
+    MCP.Service.use((mcp) =>
+      Effect.gen(function* () {
+        simulateAuthFlow = false
+        connectSucceedsImmediately = true
+        directAuthResult = "REDIRECT"
+
+        const result = yield* mcp.startAuth("test-oauth-direct")
+        expect(result.authorizationUrl).toContain("https://auth.example.com/authorize")
+        expect(result.oauthState.length).toBeGreaterThan(0)
+      }),
+    ),
+  { config: config("test-oauth-direct") },
+)
diff --git a/packages/opencode/test/mcp/oauth-browser.test.ts b/packages/opencode/test/mcp/oauth-browser.test.ts
index 16d6a2d4672..841a82a9998 100644
--- a/packages/opencode/test/mcp/oauth-browser.test.ts
+++ b/packages/opencode/test/mcp/oauth-browser.test.ts
@@ -95,6 +95,18 @@ void mock.module("@modelcontextprotocol/sdk/client/index.js", () => ({
 // Mock UnauthorizedError in the auth module
 void mock.module("@modelcontextprotocol/sdk/client/auth.js", () => ({
   UnauthorizedError: MockUnauthorizedError,
+  auth: async (
+    provider: {
+      state?: () => Promise<string>
+      saveCodeVerifier?: (v: string) => Promise<void>
+      redirectToAuthorization?: (url: URL) => Promise<void>
+    },
+  ) => {
+    await provider.state?.()
+    await provider.saveCodeVerifier?.("test-verifier")
+    await provider.redirectToAuthorization?.(new URL("https://auth.example.com/authorize?client_id=test"))
+    return "REDIRECT"
+  },
 }))
 
 beforeEach(() => {