diff --git a/client/src/webview/diagnostic-reveal.ts b/client/src/webview/diagnostic-reveal.ts
index 2a95ef6..cb8bcac 100644
--- a/client/src/webview/diagnostic-reveal.ts
+++ b/client/src/webview/diagnostic-reveal.ts
@@ -29,3 +29,12 @@ export function getDiagnosticRevealTargetFromKey(value?: string | null): Diagnos
         }
     };
 }
+
+/**
+ * Gets a key that identifies a diagnostic across verifications
+ * This is its reveal key, or, without a position, its file, title, and message, which never match the reveal key pattern
+ */
+export function getDiagnosticKey(diagnostic: LJDiagnostic): string {
+    const target = getDiagnosticRevealTarget(diagnostic);
+    return target ? getDiagnosticRevealTargetKey(target) : `${diagnostic.file}#${diagnostic.title}#${diagnostic.message}`;
+}
diff --git a/client/src/webview/script.spec.ts b/client/src/webview/script.spec.ts
index 9b814ef..b6fdd55 100644
--- a/client/src/webview/script.spec.ts
+++ b/client/src/webview/script.spec.ts
@@ -402,10 +402,29 @@ describe('webview script', () => {
         showDiagnostics([stateError('State refinement error', errorMachine('Counter', 'close'))]);
 
         expect(root.querySelector('.diagnostic-state-machine-btn')?.textContent?.trim()).toBe('Show in state machine');
-        expect(root.querySelector('.diagnostic-actions .diagnostic-state-machine-btn')).toBeNull();
-        // right below the error message, before its details
-        const firstSection = root.querySelector('.error-item .section')!;
-        expect(root.querySelector('.diagnostic-state-machine-btn')!.compareDocumentPosition(firstSection)).toBe(Node.DOCUMENT_POSITION_FOLLOWING);
+        // on the line of the title, before the other actions
+        const actions = root.querySelector('.error-item .diagnostic-title-row .diagnostic-actions')!;
+        expect(actions.firstElementChild?.classList.contains('diagnostic-state-machine-btn')).toBe(true);
+        expect(actions.querySelector('.copy-diagnostic-btn')).not.toBeNull();
+    });
+
+    it('keeps hints closed until opened, and open after a new verification', () => {
+        const error = { ...stateError('State refinement error', errorMachine('Counter', 'close')), hint: 'Call open() first' };
+        showDiagnostics([error]);
+        const hint = () => root.querySelector<HTMLDetailsElement>('.error-item .hint-section')!;
+        expect(hint().open).toBe(false);
+        expect(hint().querySelector('summary')?.textContent).toBe('Hint');
+        expect(hint().querySelector('pre')?.textContent).toBe('Call open() first');
+
+        hint().open = true;
+        hint().dispatchEvent(new Event('toggle'));
+        receive({ type: 'diagnostics', diagnostics: [{ ...error }] });
+        expect(hint().open).toBe(true);
+
+        hint().open = false;
+        hint().dispatchEvent(new Event('toggle'));
+        receive({ type: 'diagnostics', diagnostics: [{ ...error }] });
+        expect(hint().open).toBe(false);
     });
 
     it('opens on the first state error of a newly opened file', () => {
diff --git a/client/src/webview/script.ts b/client/src/webview/script.ts
index 672795e..cc44922 100644
--- a/client/src/webview/script.ts
+++ b/client/src/webview/script.ts
@@ -7,7 +7,7 @@ import type { LJDiagnostic, RefinementMismatchError, StateRefinementError } from
 import type { Range } from "../types/context";
 import type { LJStateMachine } from "../types/fsm";
 import type { ExtensionStatus } from "../state";
-import type { NavTab } from "./views/sections";
+import { setHintOpen, type NavTab } from "./views/sections";
 import { copyDiagnosticToClipboard, getDisplayDiagnostics, renderDiagnosticsView } from "./views/diagnostics/diagnostics";
 import type { LJContext } from "../types/context";
 import { ContextSectionState, renderContextView } from "./views/context/context";
@@ -56,6 +56,13 @@ export function getScript(vscode: VSCodeApi, document: Document, window: Window)
     vscode.postMessage({ type: 'ready' });    
     
     // on click
+    // toggle does not bubble, so it is caught on its way down
+    root.addEventListener('toggle', (e: Event) => {
+        const details = e.target as HTMLDetailsElement;
+        const key = details.getAttribute?.('data-hint-key');
+        if (key !== null && key !== undefined) setHintOpen(key, details.open);
+    }, true);
+
     root.addEventListener('click', (e: MouseEvent) => {
         const target = e.target instanceof Element ? e.target : null;
         if (!target) return;
diff --git a/client/src/webview/state-errors.ts b/client/src/webview/state-errors.ts
index 88e7a19..52a96a8 100644
--- a/client/src/webview/state-errors.ts
+++ b/client/src/webview/state-errors.ts
@@ -1,5 +1,5 @@
 import type { LJDiagnostic, StateRefinementError } from "../types/diagnostics";
-import { getDiagnosticRevealTarget, getDiagnosticRevealTargetKey } from "./diagnostic-reveal";
+import { getDiagnosticKey, getDiagnosticRevealTargetKey } from "./diagnostic-reveal";
 
 /**
  * Gets the state errors reported in the current file, in source order
@@ -28,9 +28,7 @@ export function getAllStateErrors(diagnostics: LJDiagnostic[] | undefined): Stat
 }
 
 export function getStateErrorKey(error: StateRefinementError): string {
-    const target = getDiagnosticRevealTarget(error);
-    // errors without a position never match the position pattern of reveal keys
-    return target ? getDiagnosticRevealTargetKey(target) : `${error.file}#${error.title}#${error.message}`;
+    return getDiagnosticKey(error);
 }
 
 /**
diff --git a/client/src/webview/styles.ts b/client/src/webview/styles.ts
index abef3e0..0a893f5 100644
--- a/client/src/webview/styles.ts
+++ b/client/src/webview/styles.ts
@@ -195,12 +195,28 @@ export function getStyles(): string {
             line-height: 1;
             pointer-events: none;
         }
+        .diagnostic-title-row {
+            display: flex;
+            flex-wrap: wrap;
+            align-items: center;
+            justify-content: space-between;
+            gap: 0.25rem 0.75rem;
+        }
+        .diagnostic-title-row h3 {
+            min-width: 0;
+        }
         .diagnostic-actions {
-            position: absolute;
-            top: 0.5rem;
-            right: 0.5rem;
             display: flex;
+            align-items: center;
             gap: 0.25rem;
+            margin-left: auto;
+        }
+        .hint-summary {
+            font-weight: bold;
+            cursor: pointer;
+        }
+        .hint-section[open] .hint-summary {
+            margin-bottom: 0.25rem;
         }
         .copy-diagnostic-btn,
         .diagnostic-context-btn {
@@ -252,8 +268,7 @@ export function getStyles(): string {
             display: inline-flex;
             align-items: center;
             gap: 0.4rem;
-            margin: 0 0 1rem;
-            padding: 0.25rem 0.6rem;
+            padding: 0.15rem 0.5rem;
             color: var(--vscode-button-secondaryForeground);
             background-color: var(--vscode-button-secondaryBackground);
             font-size: 0.85rem;
diff --git a/client/src/webview/views/diagnostics/errors.ts b/client/src/webview/views/diagnostics/errors.ts
index 1b9db34..f3d2536 100644
--- a/client/src/webview/views/diagnostics/errors.ts
+++ b/client/src/webview/views/diagnostics/errors.ts
@@ -14,6 +14,7 @@ import type {
     SyntaxError,
 } from "../../../types/diagnostics";
 import { renderCopyDiagnosticButton } from "./diagnostics";
+import { getDiagnosticKey } from "../../diagnostic-reveal";
 
 export function renderErrors(errors: LJError[]): string {
     return /*html*/`
@@ -21,11 +22,11 @@ export function renderErrors(errors: LJError[]): string {
             ${errors.map((error, index) => {
                 return /*html*/`
                 <li class="diagnostic-item error-item" ${renderDiagnosticDataAttributes(error)}>
-                    <div class="diagnostic-actions">
+                    ${renderError(error, /*html*/`
+                        ${renderDiagnosticStateMachineAction(error, index)}
                         ${renderDiagnosticContextAction(error)}
                         ${renderCopyDiagnosticButton('error', index)}
-                    </div>
-                    ${renderError(error, renderDiagnosticStateMachineAction(error, index))}
+                    `)}
                 </li>
             `;
             }).join("")}
@@ -69,15 +70,15 @@ const errorContentRenderers: ErrorRendererMap = {
 /**
  * Renders the error content
  * @param error The error to render
- * @param headerActions Actions shown below the error message
+ * @param actions Actions shown on the line of the error title
  */
-export function renderError(error: LJError, headerActions = ''): string {
+export function renderError(error: LJError, actions = ''): string {
     const message = error.type === 'refinement-error' || error.type === 'state-refinement-error' ? error.customMessage : error.message;
-    const header = renderDiagnosticHeader(error.title, message || '');
+    const header = renderDiagnosticHeader(error.title, message || '', actions);
     const content = (errorContentRenderers[error.type] as (error: LJError) => string)?.(error) || '';
-    const hint = renderHint(error.hint);
+    const hint = renderHint(error.hint, getDiagnosticKey(error));
     const location = renderLocation(error);
-    return /*html*/`${header}${headerActions}${content}${hint}${location}`;
+    return /*html*/`${header}${content}${hint}${location}`;
 }
 
 function renderDiagnosticContextAction(error: LJError): string {
diff --git a/client/src/webview/views/diagnostics/warnings.ts b/client/src/webview/views/diagnostics/warnings.ts
index 82f41b0..47de9d2 100644
--- a/client/src/webview/views/diagnostics/warnings.ts
+++ b/client/src/webview/views/diagnostics/warnings.ts
@@ -1,16 +1,14 @@
 import type { CustomWarning, ExternalClassNotFoundWarning, ExternalMethodNotFoundWarning, LJWarning, UnsatisfiableRefinementWarning } from "../../../types/diagnostics";
 import { renderDiagnosticDataAttributes, renderExpressionSection, renderDiagnosticHeader, renderHint, renderLocation } from "../sections";
 import { renderCopyDiagnosticButton } from "./diagnostics";
+import { getDiagnosticKey } from "../../diagnostic-reveal";
 
 export function renderWarnings(warnings: LJWarning[]): string {
     return /*html*/`
         <ul>
                 ${warnings.map((warning, index) => /*html*/`
                 <li class="diagnostic-item warning-item" ${renderDiagnosticDataAttributes(warning)}>
-                    <div class="diagnostic-actions">
-                        ${renderCopyDiagnosticButton('warning', index)}
-                    </div>
-                    ${renderWarning(warning)}
+                    ${renderWarning(warning, renderCopyDiagnosticButton('warning', index))}
                 </li>
             `).join("")}
         </ul>    
@@ -33,10 +31,10 @@ const warningContentRenderers: WarningContentRenderers = {
     "custom-warning": (_: CustomWarning) => ""
 };
 
-export function renderWarning(warning: LJWarning): string {
-    const header = renderDiagnosticHeader(warning.title, warning.message);
+export function renderWarning(warning: LJWarning, actions = ''): string {
+    const header = renderDiagnosticHeader(warning.title, warning.message, actions);
     const content = (warningContentRenderers[warning.type] as (warning: LJWarning) => string)?.(warning) || '';
-    const hint = renderHint(warning.hint);
+    const hint = renderHint(warning.hint, getDiagnosticKey(warning));
     const location = renderLocation(warning);
     return /*html*/`${header}${content}${hint}${location}`;
 }
diff --git a/client/src/webview/views/sections.ts b/client/src/webview/views/sections.ts
index 3dd7b6d..e72f3ef 100644
--- a/client/src/webview/views/sections.ts
+++ b/client/src/webview/views/sections.ts
@@ -21,8 +21,29 @@ export const renderSection = (title: string, body: string): string => /*html*/
 export const renderExpressionSection = (title: string, expression: string): string => /*html*/
     renderCustomSection(title, renderHighlightedExpression(expression));
 
-export const renderHint = (hint: string | null): string =>
-    hint?.trim() ? renderCustomSection('Hint', `<pre>${escapeHtml(hint.trim())}</pre>`) : '';
+// hints the user opened, kept open when the diagnostics are rendered again
+const openHints = new Set<string>();
+
+export function setHintOpen(key: string, open: boolean) {
+    if (open) openHints.add(key);
+    else openHints.delete(key);
+}
+
+/**
+ * Renders the hint of a diagnostic, closed until the user opens it
+ * @param hint The hint text
+ * @param key Identifies the diagnostic, so an opened hint stays open after a new verification
+ */
+export function renderHint(hint: string | null, key?: string): string {
+    if (!hint?.trim()) return '';
+    const open = key !== undefined && openHints.has(key);
+    return /*html*/`
+        <details class="section hint-section"${key !== undefined ? ` data-hint-key="${escapeHtml(key)}"` : ''}${open ? ' open' : ''}>
+            <summary class="hint-summary">Hint</summary>
+            <pre>${escapeHtml(hint.trim())}</pre>
+        </details>
+    `;
+}
 
 export const renderToggleSection = (title: string, targetId: string, isExpanded: boolean = true): string => /*html*/`
     <button class="context-toggle-btn" data-context-toggle="${targetId}" aria-expanded="${isExpanded ? 'true' : 'false'}" type="button">
@@ -31,8 +52,13 @@ export const renderToggleSection = (title: string, targetId: string, isExpanded:
     </button>
     `;
 
-export const renderDiagnosticHeader = (title: string, message: string): string => /*html*/
-    `<h3>${title}</h3><div class="diagnostic-header"><p>${message}</p></div>`;
+export const renderDiagnosticHeader = (title: string, message: string, actions = ''): string => /*html*/`
+    <div class="diagnostic-title-row">
+        <h3>${title}</h3>
+        ${actions.trim() ? `<div class="diagnostic-actions">${actions}</div>` : ''}
+    </div>
+    <div class="diagnostic-header"><p>${message}</p></div>
+`;
 
 export function renderDiagnosticDataAttributes(diagnostic: LJDiagnostic): string {
     const target = getDiagnosticRevealTarget(diagnostic);