diff --git a/desktop/src/app/communityViewTransition.test.mjs b/desktop/src/app/communityViewTransition.test.mjs
index 4e2c6db6d57..72fb58282f3 100644
--- a/desktop/src/app/communityViewTransition.test.mjs
+++ b/desktop/src/app/communityViewTransition.test.mjs
@@ -48,6 +48,43 @@ test("unsupported browsers execute the update and contain rejection", async () =
   assert.equal(error.mock.calls[0].arguments[1], expected);
 });
 
+test("linux webkit skips startViewTransition entirely (fixes #3931)", async () => {
+  // Even though startViewTransition is "supported" on webkitgtk, it hangs
+  // indefinitely on `transition.updateCallbackDone` when a destructive
+  // community switch removes the painted frame — freezing Linux users'
+  // windows. The Linux branch of `runCommunityViewTransition` must skip
+  // the transition API and run the update directly, regardless of
+  // startViewTransition capability.
+  const originalNavigatorDescriptor = Object.getOwnPropertyDescriptor(
+    globalThis,
+    "navigator",
+  );
+  Object.defineProperty(globalThis, "navigator", {
+    configurable: true,
+    value: { platform: "Linux x86_64", userAgent: "Buzz/0.5 webkitgtk" },
+    writable: true,
+  });
+  try {
+    const platformCalls = [];
+    const transitionCalls = [];
+    installBrowser((callback) => {
+      transitionCalls.push("startViewTransition");
+      return transitionFor(callback);
+    });
+    await runCommunityViewTransition(() => {
+      platformCalls.push("update");
+    });
+    assert.deepEqual(platformCalls, ["update"]);
+    assert.deepEqual(transitionCalls, []);
+  } finally {
+    if (originalNavigatorDescriptor) {
+      Object.defineProperty(globalThis, "navigator", originalNavigatorDescriptor);
+    } else {
+      delete globalThis.navigator;
+    }
+  }
+});
+
 test("supported transitions wait for target readiness", async () => {
   let updateFinished = false;
   let transitionFinished = false;
diff --git a/desktop/src/app/communityViewTransition.ts b/desktop/src/app/communityViewTransition.ts
index 1bbc395f9d0..e256fbb1b6a 100644
--- a/desktop/src/app/communityViewTransition.ts
+++ b/desktop/src/app/communityViewTransition.ts
@@ -1,3 +1,5 @@
+import { isLinuxPlatform } from "@/shared/lib/platform";
+
 const COMMUNITY_TRANSITION_TIMEOUT_MS = 5_000;
 
 let finishPendingTransition: (() => void) | null = null;
@@ -17,7 +19,16 @@ export async function runCommunityViewTransition(
   update: () => Promise<void> | void,
   options: { timeoutMs?: number } = {},
 ): Promise<void> {
-  if (!document.startViewTransition) {
+  // Linux WebKit (webkitgtk, as shipped by the buzz AppImage on distributions
+  // like Linux Mint) hangs indefinitely on `transition.updateCallbackDone`
+  // whenever a destructive community switch removes the currently painted
+  // frame mid-transition — the reasoning is not the 5s timeout, which does
+  // resolve `targetReady` and lets `update()` finish; the WebKit layer just
+  // never settles the view-transition promise on frame invalidation. That
+  // freezes the window and forces users to SIGKILL the app (see #3931).
+  // The transition is purely cosmetic; on Linux we lose nothing by running
+  // the update directly and skipping the browser's cross-fade.
+  if (!document.startViewTransition || isLinuxPlatform()) {
     try {
       await update();
     } catch (error) {
diff --git a/desktop/src/features/agents/lib/friendlyAgentLastError.test.mjs b/desktop/src/features/agents/lib/friendlyAgentLastError.test.mjs
index 597b1b9323e..f83df5eabf1 100644
--- a/desktop/src/features/agents/lib/friendlyAgentLastError.test.mjs
+++ b/desktop/src/features/agents/lib/friendlyAgentLastError.test.mjs
@@ -18,9 +18,11 @@ test("empty/whitespace lastError → null", () => {
   assert.equal(friendlyAgentLastError("   "), null);
 });
 
-test("buzz-acp wrapped auth failure → denied copy", () => {
+test("buzz-acp wrapped auth failure (legacy string, mesh provider) → denied copy", () => {
   const result = friendlyAgentLastError(
     "Agent reported error: llm auth: 401 unauthorized: ...",
+    null,
+    "relay-mesh",
   );
   assert.deepEqual(result, {
     severity: "denied",
@@ -28,11 +30,15 @@ test("buzz-acp wrapped auth failure → denied copy", () => {
   });
 });
 
-test("unwrapped buzz-agent prefix → denied copy", () => {
+test("unwrapped buzz-agent prefix (legacy string, mesh provider) → denied copy", () => {
   // buzz-agent's AgentError::LlmAuth Display is "llm auth: <body>"; if the
   // desktop ever picks that up directly (no AcpError wrapper), we should
-  // still recognize it as denial.
-  const result = friendlyAgentLastError("llm auth: 403 forbidden");
+  // still recognize it as denial when the agent is a mesh agent.
+  const result = friendlyAgentLastError(
+    "llm auth: 403 forbidden",
+    null,
+    "relay-mesh",
+  );
   assert.deepEqual(result, {
     severity: "denied",
     copy: RELAY_MESH_DENIED_COPY,
@@ -50,6 +56,8 @@ test("generic harness exit message → passthrough", () => {
 test("trims whitespace before matching", () => {
   const result = friendlyAgentLastError(
     "  Agent reported error: llm auth: nope\n",
+    null,
+    "relay-mesh",
   );
   assert.equal(result?.severity, "denied");
   assert.equal(result?.copy, RELAY_MESH_DENIED_COPY);
@@ -89,18 +97,45 @@ test("code -32002 → model-not-found copy (severity: denied)", () => {
   });
 });
 
-test("code -32001 → Buzz shared compute denied copy (structured path)", () => {
-  const result = friendlyAgentLastError("any error text", -32001);
+test("code -32001 → Buzz shared compute denied copy (structured path, mesh)", () => {
+  const result = friendlyAgentLastError("any error text", -32001, "relay-mesh");
   assert.deepEqual(result, {
     severity: "denied",
     copy: RELAY_MESH_DENIED_COPY,
   });
 });
 
-test("code null falls through to legacy string matching", () => {
+test("code -32001 non-mesh provider → raw message preserved", () => {
+  // Regression for #4205: a Local-OpenAI-compatible agent whose llama.cpp
+  // 401s must see the underlying message (e.g. "multi-user-authorization"),
+  // not "Community access denied".
+  const result = friendlyAgentLastError(
+    "Agent reported error (code -32001): llm auth: 401 Unauthorized: {\"message\":\"multi-user-authorization\"}",
+    -32001,
+    "openai",
+  );
+  assert.deepEqual(result, {
+    severity: "generic",
+    copy: "Agent reported error (code -32001): llm auth: 401 Unauthorized: {\"message\":\"multi-user-authorization\"}",
+  });
+});
+
+test("code -32001 null provider → raw message (conservative)", () => {
+  // When provider is absent (older record), never substitute the mesh copy —
+  // mislabeling a non-mesh 401 is worse than showing more detail to a mesh
+  // user.
+  const result = friendlyAgentLastError("any error text", -32001, null);
+  assert.deepEqual(result, {
+    severity: "generic",
+    copy: "any error text",
+  });
+});
+
+test("code null falls through to legacy string matching (mesh)", () => {
   const result = friendlyAgentLastError(
     "Agent reported error: llm auth: 401 unauthorized",
     null,
+    "relay-mesh",
   );
   assert.deepEqual(result, {
     severity: "denied",
@@ -108,10 +143,11 @@ test("code null falls through to legacy string matching", () => {
   });
 });
 
-test("code undefined falls through to legacy string matching", () => {
+test("code undefined falls through to legacy string matching (mesh)", () => {
   const result = friendlyAgentLastError(
     "Agent reported error: llm auth: 403 forbidden",
     undefined,
+    "relay-mesh",
   );
   assert.deepEqual(result, {
     severity: "denied",
@@ -134,13 +170,24 @@ test("friendlyTurnErrorCopy: numeric code -32002 → model-not-found copy", () =
   );
 });
 
-test("friendlyTurnErrorCopy: string-encoded code coerces to number", () => {
+test("friendlyTurnErrorCopy: string-encoded code coerces to number (mesh)", () => {
   assert.equal(
-    friendlyTurnErrorCopy("raw error", "-32001"),
+    friendlyTurnErrorCopy("raw error", "-32001", "relay-mesh"),
     RELAY_MESH_DENIED_COPY,
   );
 });
 
+test("friendlyTurnErrorCopy: -32001 non-mesh → raw text preserved", () => {
+  assert.equal(
+    friendlyTurnErrorCopy(
+      "llm auth: 401 Unauthorized: multi-user-authorization",
+      -32001,
+      "openai",
+    ),
+    "llm auth: 401 Unauthorized: multi-user-authorization",
+  );
+});
+
 test("friendlyTurnErrorCopy: missing code falls back to raw text", () => {
   assert.equal(friendlyTurnErrorCopy("raw error", undefined), "raw error");
   assert.equal(friendlyTurnErrorCopy("raw error", null), "raw error");
@@ -165,19 +212,25 @@ test("unknown code prevents string-pattern cross-classification", () => {
   });
 });
 
-test("NaN code param treated as absent — string path applies", () => {
-  // NaN is not finite; falls back to string matching.
-  const result = friendlyAgentLastError("llm auth: denied", NaN);
+test("NaN code param treated as absent — legacy string path applies (mesh)", () => {
+  // NaN is not finite; falls back to string matching. Mesh provider preserves
+  // the historical denied-copy mapping for the legacy form.
+  const result = friendlyAgentLastError(
+    "llm auth: denied",
+    NaN,
+    "relay-mesh",
+  );
   assert.deepEqual(result, {
     severity: "denied",
     copy: RELAY_MESH_DENIED_COPY,
   });
 });
 
-test("embedded code -32001 recovered from message when code param is null", () => {
+test("embedded code -32001 recovered from message when code param is null (mesh)", () => {
   const result = friendlyAgentLastError(
     "Agent reported error (code -32001): llm auth: 401",
     null,
+    "relay-mesh",
   );
   assert.deepEqual(result, {
     severity: "denied",
@@ -185,6 +238,19 @@ test("embedded code -32001 recovered from message when code param is null", () =
   });
 });
 
+test("embedded code -32001, non-mesh provider → raw preserved (regression)", () => {
+  // Even the embedded-code fallback must respect the provider gate.
+  const result = friendlyAgentLastError(
+    "Agent reported error (code -32001): llm auth: 401 from api.openai.com",
+    null,
+    "openai",
+  );
+  assert.deepEqual(result, {
+    severity: "generic",
+    copy: "Agent reported error (code -32001): llm auth: 401 from api.openai.com",
+  });
+});
+
 test("embedded code -32002 recovered from message when code param is undefined", () => {
   const result = friendlyAgentLastError(
     "Agent reported error (code -32002): llm model not found: x",
@@ -207,10 +273,10 @@ test("embedded unknown code is authoritative — no cross-classification", () =>
   });
 });
 
-test("friendlyTurnErrorCopy: garbage string code coerces to NaN → string path", () => {
+test("friendlyTurnErrorCopy: garbage string code coerces to NaN → legacy string path (mesh)", () => {
   // "garbage" → NaN → not finite → null → string prefix matches "llm auth:".
   assert.equal(
-    friendlyTurnErrorCopy("llm auth: denied", "garbage"),
+    friendlyTurnErrorCopy("llm auth: denied", "garbage", "relay-mesh"),
     RELAY_MESH_DENIED_COPY,
   );
 });
@@ -307,10 +373,16 @@ test("friendlyTurnErrorCopy: code -32603 bare Internal error → cli-acp interna
 });
 
 test("-32603 does not affect -32001/-32002 classification (regression)", () => {
-  assert.deepEqual(friendlyAgentLastError("any", -32001), {
+  assert.deepEqual(friendlyAgentLastError("any", -32001, "relay-mesh"), {
     severity: "denied",
     copy: RELAY_MESH_DENIED_COPY,
   });
+  // -32001 non-mesh now passes raw through (the #4205 fix); -32002 is
+  // provider-independent.
+  assert.deepEqual(friendlyAgentLastError("any", -32001, "openai"), {
+    severity: "generic",
+    copy: "any",
+  });
   assert.deepEqual(friendlyAgentLastError("any", -32002), {
     severity: "denied",
     copy: MODEL_NOT_FOUND_COPY,
diff --git a/desktop/src/features/agents/lib/friendlyAgentLastError.ts b/desktop/src/features/agents/lib/friendlyAgentLastError.ts
index 60c77bb04cc..a6e7028acc4 100644
--- a/desktop/src/features/agents/lib/friendlyAgentLastError.ts
+++ b/desktop/src/features/agents/lib/friendlyAgentLastError.ts
@@ -64,6 +64,7 @@ function recoverEmbeddedCode(trimmed: string): {
 export function friendlyAgentLastError(
   raw: string | null,
   code?: number | null,
+  provider?: string | null,
 ): FriendlyAgentLastError | null {
   if (raw == null) return null;
   const trimmed = raw.trim();
@@ -78,7 +79,18 @@ export function friendlyAgentLastError(
   if (effectiveCode != null) {
     switch (effectiveCode) {
       case -32001:
-        return { severity: "denied", copy: RELAY_MESH_DENIED_COPY };
+        // `-32001` is a generic buzz-agent llm-auth failure — it fires for
+        // *any* LLM provider (anthropic, openai, databricks, openai-compat…),
+        // not only relay-mesh. Rewriting it to the mesh copy misdirects
+        // users debugging a non-mesh agent: they see "Community access
+        // denied" when the real fix is "your configured API key was rejected
+        // by your upstream". Only when the agent's provider is the mesh
+        // preset do we know the 401 came from Buzz's own admission and can
+        // afford the more actionable mesh copy.
+        if (provider != null && provider.trim() === "relay-mesh") {
+          return { severity: "denied", copy: RELAY_MESH_DENIED_COPY };
+        }
+        return { severity: "generic", copy: trimmed };
       case -32002:
         return { severity: "denied", copy: MODEL_NOT_FOUND_COPY };
       case -32603: {
@@ -106,11 +118,19 @@ export function friendlyAgentLastError(
 
   // Legacy string fallback for records written before codes existed.
   // Match either the unwrapped buzz-agent prefix or the buzz-acp v0 wrap.
+  // Same overbroad-rewriting concern as the structured path: "llm auth:"
+  // fires for any provider's 401/403, so only relay-mesh agents can safely
+  // be summarised as "community access denied". For everyone else, keep the
+  // underlying message so the actionable cause (upstream auth rejected your
+  // key) is preserved.
   if (
     trimmed.startsWith("Agent reported error: llm auth:") ||
     trimmed.startsWith("llm auth:")
   ) {
-    return { severity: "denied", copy: RELAY_MESH_DENIED_COPY };
+    if (provider != null && provider.trim() === "relay-mesh") {
+      return { severity: "denied", copy: RELAY_MESH_DENIED_COPY };
+    }
+    return { severity: "generic", copy: trimmed };
   }
 
   return { severity: "generic", copy: trimmed };
@@ -120,9 +140,19 @@ export function friendlyAgentLastError(
  * Convenience for `turn_error` / `agent_panic` observer payloads: coerce the
  * payload's untyped `code` JSON value and return the display copy, falling
  * back to the raw error text when no classification applies.
+ *
+ * `provider` must be the agent's configured LLM provider (e.g. "anthropic",
+ * "relay-mesh"). It's threaded through to [`friendlyAgentLastError`] so the
+ * `-32001` → mesh-copy rewrite fires only for mesh agents; non-mesh agents
+ * keep their underlying llm-auth message (upstream 401 details are the
+ * actionable signal).
  */
-export function friendlyTurnErrorCopy(raw: string, code: unknown): string {
+export function friendlyTurnErrorCopy(
+  raw: string,
+  code: unknown,
+  provider?: string | null,
+): string {
   const numeric = code == null ? null : Number(code);
   const safe = Number.isFinite(numeric) ? (numeric as number) : null;
-  return friendlyAgentLastError(raw, safe)?.copy ?? raw;
+  return friendlyAgentLastError(raw, safe, provider)?.copy ?? raw;
 }
diff --git a/desktop/src/features/agents/ui/ManagedAgentRow.tsx b/desktop/src/features/agents/ui/ManagedAgentRow.tsx
index 606d2b78836..a9f73a2ebbe 100644
--- a/desktop/src/features/agents/ui/ManagedAgentRow.tsx
+++ b/desktop/src/features/agents/ui/ManagedAgentRow.tsx
@@ -87,11 +87,15 @@ export function ManagedAgentRow({
   // log tail (Max's seam in `managed_agents/storage.rs`), promote it to
   // user-visible copy below the process detail. Specifically renders the
   // friendly "Community access denied this agent — check its community membership."
-  // for auth failures so the user knows it's a membership thing, not a
-  // crash. Generic exits stay verbatim so we don't lie about other failures.
+  // for auth failures when the agent is a Buzz shared-compute (relay-mesh)
+  // agent; for non-mesh agents, the raw llm-auth message is preserved so a
+  // llama.cpp / OpenAI / Databricks 401 isn't mislabeled as a community
+  // membership problem (see #4205). Generic exits stay verbatim so we don't
+  // lie about other failures.
   const friendlyError = friendlyAgentLastError(
     agent.lastError,
     agent.lastErrorCode,
+    agent.provider,
   );
 
   return (
diff --git a/desktop/src/features/agents/ui/UnifiedAgentsSection.tsx b/desktop/src/features/agents/ui/UnifiedAgentsSection.tsx
index 19a5ef1171f..acb34259518 100644
--- a/desktop/src/features/agents/ui/UnifiedAgentsSection.tsx
+++ b/desktop/src/features/agents/ui/UnifiedAgentsSection.tsx
@@ -284,7 +284,11 @@ function AgentPersonaCard({
     ? firstAvatarUrl(persona.avatarUrl, profileQuery.data?.avatarUrl)
     : persona.avatarUrl;
   const friendlyError = agent
-    ? friendlyAgentLastError(agent.lastError, agent.lastErrorCode)?.copy
+    ? friendlyAgentLastError(
+        agent.lastError,
+        agent.lastErrorCode,
+        agent.provider,
+      )?.copy
     : null;
   const opensRuntimeTab = Boolean(agent && friendlyError && !isActive);
 
@@ -375,6 +379,7 @@ function StandaloneAgentCard({
   const friendlyError = friendlyAgentLastError(
     agent.lastError,
     agent.lastErrorCode,
+    agent.provider,
   )?.copy;
   const isActive = isManagedAgentActive(agent);
   const opensRuntimeTab = Boolean(friendlyError && !isActive);