diff --git a/src/components/error-display/__tests__/error-display.test.tsx b/src/components/error-display/__tests__/error-display.test.tsx
index 4a215fd0..8e94b37b 100644
--- a/src/components/error-display/__tests__/error-display.test.tsx
+++ b/src/components/error-display/__tests__/error-display.test.tsx
@@ -52,7 +52,7 @@ describe('ErrorDisplay', () => {
     vi.useRealTimers();
   });
 
-  it('waits before rendering, then copies structured errors and shows feedback', async () => {
+  it('waits before rendering, then shows a copy action for structured errors', async () => {
     testState.copyToClipboardMock.mockResolvedValue(undefined);
     const error = {
       details: { code: 500 },
@@ -67,20 +67,22 @@ describe('ErrorDisplay', () => {
     });
 
     const button = container.querySelector('button');
-    expect(button?.textContent).toContain('error: network down');
+    expect(container.textContent).toContain('error: network down: code: 500');
+    expect(button?.textContent).toBe('copy full error');
 
     await act(async () => {
       button?.dispatchEvent(new MouseEvent('click', { bubbles: true }));
     });
 
     expect(testState.copyToClipboardMock).toHaveBeenCalledWith(JSON.stringify(error, null, 2));
-    expect(container.textContent).toContain('full error copied to the clipboard');
+    expect(container.textContent).toContain('copied');
 
     act(() => {
       vi.advanceTimersByTime(1500);
     });
 
-    expect(container.textContent).toContain('error: network down');
+    expect(container.textContent).toContain('error: network down: code: 500');
+    expect(button?.textContent).toBe('copy full error');
   });
 
   it('shows copy failure feedback and logs the clipboard error', async () => {
@@ -93,6 +95,7 @@ describe('ErrorDisplay', () => {
 
     const button = container.querySelector('button');
     expect(button).toBeTruthy();
+    expect(button?.textContent).toBe('copy full error');
 
     await act(async () => {
       button?.dispatchEvent(new MouseEvent('click', { bubbles: true }));
@@ -115,7 +118,8 @@ describe('ErrorDisplay', () => {
     });
 
     const button = container.querySelector('button');
-    expect(button?.textContent).toContain('error: native failure');
+    expect(container.textContent).toContain('error: native failure: status: 504');
+    expect(button?.textContent).toBe('copy full error');
 
     await act(async () => {
       button?.dispatchEvent(new MouseEvent('click', { bubbles: true }));
@@ -135,6 +139,68 @@ describe('ErrorDisplay', () => {
     );
   });
 
+  it('copies nested cyclic errors as readable valid JSON', async () => {
+    testState.copyToClipboardMock.mockResolvedValue(undefined);
+    const cause = new Error('provider timeout');
+    cause.stack = 'Error: provider timeout\n    at provider';
+    const error = Object.assign(new Error('publish failed'), {
+      attempts: [
+        {
+          elapsedMs: BigInt(5000),
+          provider: 'pubsub',
+          reason: cause,
+        },
+      ],
+    });
+    Object.assign(error, { self: error });
+    error.stack = 'Error: publish failed\n    at publish';
+
+    await renderDisplay(error);
+    act(() => {
+      vi.advanceTimersByTime(1000);
+    });
+
+    const button = container.querySelector('button');
+    await act(async () => {
+      button?.dispatchEvent(new MouseEvent('click', { bubbles: true }));
+    });
+
+    const copied = testState.copyToClipboardMock.mock.calls[0]?.[0];
+    expect(copied).toBeTypeOf('string');
+    const parsed = JSON.parse(copied as string);
+    expect(parsed).toMatchObject({
+      attempts: [
+        {
+          elapsedMs: '5000',
+          provider: 'pubsub',
+          reason: {
+            message: 'provider timeout',
+            name: 'Error',
+          },
+        },
+      ],
+      message: 'publish failed',
+      name: 'Error',
+      self: '[Circular]',
+    });
+  });
+
+  it('copies empty structured errors as valid JSON', async () => {
+    testState.copyToClipboardMock.mockResolvedValue(undefined);
+
+    await renderDisplay({});
+    act(() => {
+      vi.advanceTimersByTime(1000);
+    });
+
+    const button = container.querySelector('button');
+    await act(async () => {
+      button?.dispatchEvent(new MouseEvent('click', { bubbles: true }));
+    });
+
+    expect(testState.copyToClipboardMock).toHaveBeenCalledWith('{}');
+  });
+
   it('supports compact custom labels that copy plain string errors immediately', async () => {
     testState.copyToClipboardMock.mockResolvedValue(undefined);
 
@@ -146,14 +212,15 @@ describe('ErrorDisplay', () => {
     });
 
     const button = container.querySelector('button');
-    expect(button?.textContent).toBe('failed');
+    expect(container.textContent).toContain('failed');
+    expect(button?.textContent).toBe('copy full error');
 
     await act(async () => {
       button?.dispatchEvent(new MouseEvent('click', { bubbles: true }));
     });
 
     expect(testState.copyToClipboardMock).toHaveBeenCalledWith('All pubsub providers throw an error and unable to publish or subscribe');
-    expect(container.textContent).toContain('full error copied to the clipboard');
+    expect(container.textContent).toContain('copied');
   });
 
   it('renders plain string errors after the delay and hides again when the error clears', async () => {
diff --git a/src/components/error-display/error-display.module.css b/src/components/error-display/error-display.module.css
index ba1ebfd7..eb2e48ba 100644
--- a/src/components/error-display/error-display.module.css
+++ b/src/components/error-display/error-display.module.css
@@ -1,29 +1,50 @@
 .error {
   padding: 10px;
   text-align: center;
+  display: flex;
+  align-items: baseline;
+  justify-content: center;
+  gap: 6px;
+  flex-wrap: wrap;
 }
 
 .inlineError {
   display: inline-flex;
-  align-items: center;
+  align-items: baseline;
+  gap: 6px;
+  flex-wrap: wrap;
 }
 
 .errorMessage {
   color: red;
+  overflow-wrap: anywhere;
 }
 
-.clickableErrorMessage {
+.copyErrorButtonWrapper {
+  display: inline-flex;
+  align-items: baseline;
+  gap: 1px;
+  color: var(--button-desktop-text-color);
+  white-space: nowrap;
+}
+
+.copyErrorButton {
   all: unset;
   font: inherit;
-  color: red;
+  color: var(--button-desktop-text-color);
+  text-decoration: var(--button-text-decoration);
   cursor: pointer;
   display: inline;
 }
 
-.clickableErrorMessage:hover {
-  text-decoration: underline;
+.copyErrorButton:hover {
+  color: var(--button-desktop-text-color-hover);
 }
 
 .feedbackSuccessMessage {
   color: inherit;
 }
+
+.feedbackFailedMessage {
+  color: red;
+}
diff --git a/src/components/error-display/error-display.tsx b/src/components/error-display/error-display.tsx
index b0172b31..73a580bb 100644
--- a/src/components/error-display/error-display.tsx
+++ b/src/components/error-display/error-display.tsx
@@ -1,43 +1,21 @@
 import { useReducer, useEffect } from 'react';
 import { useTranslation } from 'react-i18next';
 import { copyToClipboard } from '../../lib/utils/clipboard-utils';
+import { formatErrorForDisplay, serializeErrorForClipboard } from '../../lib/utils/error-utils';
 import styles from './error-display.module.css';
 
-type State = { showAfterDelay: boolean; feedbackMessageKey: string | null };
+type FeedbackMessageKey = 'copied' | 'failed' | null;
+type State = { showAfterDelay: boolean; feedbackMessageKey: FeedbackMessageKey };
 
-function reducer(state: State, action: { type: 'RESET_DELAY' } | { type: 'SHOW' } | { type: 'FEEDBACK'; payload: string | null }): State {
+function reducer(state: State, action: { type: 'RESET_DELAY' } | { type: 'SHOW' } | { type: 'FEEDBACK'; payload: FeedbackMessageKey }): State {
   if (action.type === 'RESET_DELAY') return { ...state, showAfterDelay: false };
   if (action.type === 'SHOW') return { ...state, showAfterDelay: true };
   if (action.type === 'FEEDBACK') return { ...state, feedbackMessageKey: action.payload };
   return state;
 }
 
-const serializeErrorForClipboard = (error: unknown): string => {
-  if (typeof error === 'string') {
-    return error;
-  }
-
-  const serializableError =
-    error instanceof Error
-      ? {
-          name: error.name,
-          message: error.message,
-          stack: error.stack,
-          ...Object.fromEntries(Object.entries(error)),
-          ...('cause' in error && error.cause ? { cause: error.cause } : {}),
-        }
-      : error;
-
-  try {
-    const serializedError = JSON.stringify(serializableError, null, 2);
-    return serializedError && serializedError !== '{}' ? serializedError : String(error);
-  } catch {
-    return String(error);
-  }
-};
-
 type ErrorDisplayProps = {
-  error: any;
+  error: unknown;
   displayMessage?: string;
   inline?: boolean;
   showImmediately?: boolean;
@@ -47,7 +25,7 @@ const ErrorDisplay = ({ error, displayMessage, inline = false, showImmediately =
   const { t } = useTranslation();
   const [state, dispatch] = useReducer(reducer, { showAfterDelay: showImmediately, feedbackMessageKey: null });
 
-  const hasError = !!(error?.message || error?.stack || error?.details || error);
+  const hasError = error !== null && error !== undefined && error !== '';
 
   useEffect(() => {
     if (!hasError) {
@@ -66,10 +44,11 @@ const ErrorDisplay = ({ error, displayMessage, inline = false, showImmediately =
     return null;
   }
 
-  const originalDisplayMessage = displayMessage || (error?.message ? `${t('error')}: ${error.message}` : typeof error === 'string' ? error : error ? t('error') : null);
-  const canCopyError = !!error && !!originalDisplayMessage;
+  const formattedError = formatErrorForDisplay(error);
+  const originalDisplayMessage = displayMessage ?? (formattedError ? (typeof error === 'string' ? formattedError : `${t('error')}: ${formattedError}`) : t('error'));
+  const canCopyError = hasError && !!originalDisplayMessage;
 
-  const handleMessageClick = async () => {
+  const handleCopyError = async () => {
     if (!canCopyError || state.feedbackMessageKey) return;
 
     const errorString = serializeErrorForClipboard(error);
@@ -84,46 +63,27 @@ const ErrorDisplay = ({ error, displayMessage, inline = false, showImmediately =
     }
   };
 
-  let currentDisplayMessage = '';
-  const classNames: string[] = [];
-  let isClickable = false;
-
+  const copyButtonLabel =
+    state.feedbackMessageKey === 'copied' ? t('copied') : state.feedbackMessageKey === 'failed' ? t('copyFailed', 'copy failed') : t('copyFullError', 'copy full error');
+  const copyButtonClassNames = [styles.copyErrorButton];
   if (state.feedbackMessageKey === 'copied') {
-    currentDisplayMessage = t('fullErrorCopiedToClipboard', 'full error copied to the clipboard');
-    classNames.push(styles.feedbackSuccessMessage);
+    copyButtonClassNames.push(styles.feedbackSuccessMessage);
   } else if (state.feedbackMessageKey === 'failed') {
-    currentDisplayMessage = t('copyFailed', 'copy failed');
-    classNames.push(styles.errorMessage);
-  } else if (originalDisplayMessage) {
-    currentDisplayMessage = originalDisplayMessage;
-    classNames.push(styles.errorMessage);
-    isClickable = canCopyError;
-    if (isClickable) {
-      classNames.push(styles.clickableErrorMessage);
-    }
+    copyButtonClassNames.push(styles.feedbackFailedMessage);
   }
 
   return (
     <div className={inline ? styles.inlineError : styles.error}>
-      {currentDisplayMessage &&
-        (isClickable ? (
-          <button
-            type='button'
-            className={classNames.join(' ')}
-            onClick={handleMessageClick}
-            onKeyDown={(e) => {
-              if (e.key === 'Enter' || e.key === ' ') {
-                e.preventDefault();
-                handleMessageClick();
-              }
-            }}
-            title={t('clickToCopyFullError', 'Click to copy full error')}
-          >
-            {currentDisplayMessage}
+      {originalDisplayMessage && <span className={styles.errorMessage}>{originalDisplayMessage}</span>}
+      {canCopyError && (
+        <span className={styles.copyErrorButtonWrapper}>
+          [
+          <button type='button' className={copyButtonClassNames.join(' ')} onClick={handleCopyError} title={t('copyFullError', 'copy full error')}>
+            {copyButtonLabel}
           </button>
-        ) : (
-          <span className={classNames.join(' ')}>{currentDisplayMessage}</span>
-        ))}
+          ]
+        </span>
+      )}
     </div>
   );
 };
diff --git a/src/lib/utils/__tests__/error-utils.test.ts b/src/lib/utils/__tests__/error-utils.test.ts
index f8ed23f2..105c2443 100644
--- a/src/lib/utils/__tests__/error-utils.test.ts
+++ b/src/lib/utils/__tests__/error-utils.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest';
-import { formatErrorForDisplay } from '../error-utils';
+import { formatErrorForDisplay, serializeErrorForClipboard } from '../error-utils';
 
 describe('error utils', () => {
   it('returns plain string errors unchanged', () => {
@@ -29,4 +29,55 @@ describe('error utils', () => {
       }),
     ).toBe('publish failed: provider: plebpubsub; reason: timeout');
   });
+
+  it('formats nested Error details without dropping the nested message', () => {
+    expect(
+      formatErrorForDisplay({
+        details: {
+          reason: new Error('provider timeout'),
+        },
+        message: 'publish failed',
+      }),
+    ).toBe('publish failed: reason: provider timeout');
+  });
+
+  it('formats cyclic errors without recursing forever', () => {
+    const error = Object.assign(new Error('publish failed'), {
+      details: {
+        elapsedMs: BigInt(5000),
+      },
+    });
+    Object.assign(error.details, { self: error.details });
+
+    expect(formatErrorForDisplay(error)).toBe('publish failed: elapsedMs: 5000; self: [Circular]');
+  });
+
+  it('serializes cyclic errors as valid JSON for copying', () => {
+    const cause = new Error('provider timeout');
+    const error = Object.assign(new Error('publish failed'), {
+      attempts: [{ elapsedMs: BigInt(5000), provider: 'pubsub', reason: cause }],
+    });
+    Object.assign(error, { self: error });
+
+    expect(JSON.parse(serializeErrorForClipboard(error))).toMatchObject({
+      attempts: [
+        {
+          elapsedMs: '5000',
+          provider: 'pubsub',
+          reason: {
+            message: 'provider timeout',
+            name: 'Error',
+          },
+        },
+      ],
+      message: 'publish failed',
+      name: 'Error',
+      self: '[Circular]',
+    });
+  });
+
+  it('keeps string errors unchanged and empty objects as JSON', () => {
+    expect(serializeErrorForClipboard('plain failure')).toBe('plain failure');
+    expect(serializeErrorForClipboard({})).toBe('{}');
+  });
 });
diff --git a/src/lib/utils/error-utils.ts b/src/lib/utils/error-utils.ts
index 91cc8392..d49ef36e 100644
--- a/src/lib/utils/error-utils.ts
+++ b/src/lib/utils/error-utils.ts
@@ -4,27 +4,160 @@ type ErrorLike = {
   message?: unknown;
 };
 
-const normalizeUnknownErrorPart = (value: unknown): string | undefined => {
+const CIRCULAR_REFERENCE_LABEL = '[Circular]';
+const UNDEFINED_LABEL = '[undefined]';
+
+const normalizeErrorForClipboard = (value: unknown, seen = new WeakSet<object>()): unknown => {
+  if (value === null) {
+    return null;
+  }
+  if (value === undefined) {
+    return UNDEFINED_LABEL;
+  }
+  if (typeof value === 'bigint') {
+    return value.toString();
+  }
+  if (typeof value === 'number' || typeof value === 'boolean' || typeof value === 'string') {
+    return value;
+  }
+  if (typeof value === 'symbol' || typeof value === 'function') {
+    return String(value);
+  }
+  if (value instanceof Date) {
+    return Number.isNaN(value.getTime()) ? String(value) : value.toISOString();
+  }
+  if (value instanceof Error) {
+    if (seen.has(value)) {
+      return CIRCULAR_REFERENCE_LABEL;
+    }
+    seen.add(value);
+    const normalized: Record<string, unknown> = {
+      name: value.name,
+      message: value.message,
+    };
+    if (value.stack) {
+      normalized.stack = value.stack;
+    }
+    for (const [key, entryValue] of Object.entries(value)) {
+      normalized[key] = normalizeErrorForClipboard(entryValue, seen);
+    }
+    if ('cause' in value && value.cause !== undefined) {
+      normalized.cause = normalizeErrorForClipboard(value.cause, seen);
+    }
+    seen.delete(value);
+    return normalized;
+  }
+  if (Array.isArray(value)) {
+    if (seen.has(value)) {
+      return CIRCULAR_REFERENCE_LABEL;
+    }
+    seen.add(value);
+    const normalized = value.map((entry) => normalizeErrorForClipboard(entry, seen));
+    seen.delete(value);
+    return normalized;
+  }
+  if (value instanceof Map) {
+    if (seen.has(value)) {
+      return CIRCULAR_REFERENCE_LABEL;
+    }
+    seen.add(value);
+    const normalized = Object.fromEntries([...value.entries()].map(([key, entryValue]) => [String(key), normalizeErrorForClipboard(entryValue, seen)]));
+    seen.delete(value);
+    return normalized;
+  }
+  if (value instanceof Set) {
+    if (seen.has(value)) {
+      return CIRCULAR_REFERENCE_LABEL;
+    }
+    seen.add(value);
+    const normalized = [...value].map((entry) => normalizeErrorForClipboard(entry, seen));
+    seen.delete(value);
+    return normalized;
+  }
+  if (typeof value === 'object') {
+    if (seen.has(value)) {
+      return CIRCULAR_REFERENCE_LABEL;
+    }
+    seen.add(value);
+    const normalized: Record<string, unknown> = {};
+    for (const [key, entryValue] of Object.entries(value as Record<string, unknown>)) {
+      normalized[key] = normalizeErrorForClipboard(entryValue, seen);
+    }
+    seen.delete(value);
+    return normalized;
+  }
+  return String(value);
+};
+
+export const serializeErrorForClipboard = (error: unknown): string => {
+  if (typeof error === 'string') {
+    return error;
+  }
+
+  const serializableError = normalizeErrorForClipboard(error);
+
+  try {
+    return JSON.stringify(serializableError, null, 2) ?? String(error);
+  } catch {
+    return String(error);
+  }
+};
+
+const normalizeUnknownErrorPart = (value: unknown, seen = new WeakSet<object>()): string | undefined => {
   if (value === null || value === undefined) {
     return undefined;
   }
   if (typeof value === 'string') {
     return value.trim() || undefined;
   }
-  if (typeof value === 'number' || typeof value === 'boolean') {
+  if (typeof value === 'number' || typeof value === 'boolean' || typeof value === 'bigint') {
     return String(value);
   }
+  if (typeof value === 'symbol' || typeof value === 'function') {
+    return String(value);
+  }
+  if (value instanceof Error) {
+    if (seen.has(value)) {
+      return CIRCULAR_REFERENCE_LABEL;
+    }
+    seen.add(value);
+    const parts = [normalizeUnknownErrorPart(value.message, seen)];
+    for (const [key, entryValue] of Object.entries(value)) {
+      const normalizedValue = normalizeUnknownErrorPart(entryValue, seen);
+      if (normalizedValue) {
+        parts.push(`${key}: ${normalizedValue}`);
+      }
+    }
+    if ('cause' in value) {
+      const normalizedCause = normalizeUnknownErrorPart(value.cause, seen);
+      if (normalizedCause) {
+        parts.push(`cause: ${normalizedCause}`);
+      }
+    }
+    seen.delete(value);
+    return parts.filter(Boolean).join('; ') || value.name;
+  }
   if (Array.isArray(value)) {
-    const parts = value.map(normalizeUnknownErrorPart).filter(Boolean);
+    if (seen.has(value)) {
+      return CIRCULAR_REFERENCE_LABEL;
+    }
+    seen.add(value);
+    const parts = value.map((entryValue) => normalizeUnknownErrorPart(entryValue, seen)).filter(Boolean);
+    seen.delete(value);
     return parts.length ? parts.join('; ') : undefined;
   }
   if (typeof value === 'object') {
+    if (seen.has(value)) {
+      return CIRCULAR_REFERENCE_LABEL;
+    }
+    seen.add(value);
     const entries = Object.entries(value as Record<string, unknown>)
       .map(([key, entryValue]) => {
-        const normalizedValue = normalizeUnknownErrorPart(entryValue);
+        const normalizedValue = normalizeUnknownErrorPart(entryValue, seen);
         return normalizedValue ? `${key}: ${normalizedValue}` : undefined;
       })
       .filter(Boolean);
+    seen.delete(value);
 
     if (entries.length) {
       return entries.join('; ');