Show notes from similar earlier incidents

Each incident gets a signature: the alert name plus the group labels that
say what is broken, minus the ones that only say where it ran (instance,
pod, container, ...). GET /api/incidents/{id}/similar returns resolved
incidents in the same team with the same signature that have notes.

Notes can be marked as the resolution note, "what fixed it", either with a
resolution field on resolve or pinned on a note. Those lead the similar
list, show on the incident page as "Seen before", and the triggered
notification carries the latest one.

Claude-Session: https://claude.ai/code/session_01MMados3BD1oSjevHxbmVqU

internal/web/static/js/incident.js

@@ -17,6 +17,7 @@ const pane = () => document.getElementById('detail');
 let currentID = null;
 let inc = null;
 let events = [];
+let similarList = [];
 let error = null;
 let busy = false;
 
@@ -38,10 +39,15 @@ export async function refresh() {
   const id = currentID;
   if (id == null) return;
   try {
-    const [i, t] = await Promise.all([api.incident(id), api.timeline(id)]);
+    // Similar incidents are a courtesy: an older server answers 404 and a
+    // failure here must not hide the incident itself.
+    const [i, t, sim] = await Promise.all([
+      api.incident(id), api.timeline(id), api.similar(id).catch(() => []),
+    ]);
     if (id !== currentID) return;
     inc = i;
     events = t;
+    similarList = sim;
     error = null;
   } catch (err) {
     if (id !== currentID) return;
@@ -81,6 +87,7 @@ function render() {
       facts(),
       groupLabels(),
       alertsSection(),
+      similarSection(),
       timelineSection(),
     ),
     actionBar(),
@@ -197,6 +204,7 @@ function eventText(ev) {
     case 'unsnoozed': return [strong(person), ' ended the snooze'];
     case 'resolved': return person ? [strong(person), ' resolved the incident'] : ['Resolved: every alert stopped firing'];
     case 'note': return [strong(person), ' added a note'];
+    case 'resolution_note': return [strong(person), ' noted what fixed it'];
     case 'notified': {
       const to = person ? strong(person) : 'the fallback topic';
       if (ev.detail === 'reminder') return ['Reminder sent to ', to];
@@ -209,6 +217,22 @@ function eventText(ev) {
   }
 }
 
+// Earlier incidents with the same signature that someone left notes on, the
+// ones that recorded what fixed it first. Plain notes are on that incident's
+// own page.
+function similarSection() {
+  if (!similarList.length) return null;
+  return h('section', { class: 'section' },
+    h('h2', { class: 'section-title' }, h('span', { text: 'Seen before' })),
+    h('div', { class: 'card' },
+      h('ul', { class: 'similar' }, similarList.map((s) => h('li', { class: 'similar-item' },
+        h('a', { href: `/incidents/${s.id}`, text: `#${s.id} ${s.title}` }),
+        h('div', { class: 'sub', text: `${when(s.resolved_at)} · ${ago(s.resolved_at)}${s.note_count ? ` · ${s.note_count} note${s.note_count === 1 ? '' : 's'}` : ''}` }),
+        ...s.resolution_notes.map((n) => h('div', { class: 'note note-fix', text: n.detail || '' })),
+      )))),
+  );
+}
+
 function timelineSection() {
   const sorted = [...events].sort((a, b) => Date.parse(a.created_at) - Date.parse(b.created_at) || a.id - b.id);
   return h('section', { class: 'section' },
@@ -223,14 +247,16 @@ function timelineSection() {
   );
 }
 
+const isNote = (ev) => ev.type === 'note' || ev.type === 'resolution_note';
+
 function timelineItem(ev) {
-  const mine = ev.type === 'note' && ev.user_id === myID();
+  const mine = isNote(ev) && ev.user_id === myID();
   return h('li', { class: `tl-item tl-${ev.type}` },
     h('span', { class: 'tl-dot' }),
     h('div', { class: 'tl-body' },
       h('div', { class: 'tl-text' }, eventText(ev)),
       h('div', { class: 'tl-time', title: ev.created_at, text: `${when(ev.created_at)} · ${ago(ev.created_at)}` }),
-      ev.type === 'note' && h('div', { class: 'note', text: ev.detail || '' }),
+      isNote(ev) && h('div', { class: ev.type === 'resolution_note' ? 'note note-fix' : 'note', text: ev.detail || '' }),
       mine && h('div', { class: 'note-actions' },
         h('button', { class: 'btn btn-ghost btn-sm', type: 'button', onclick: () => deleteNote(ev) }, icon('trash'), 'Delete')),
     ),
@@ -296,15 +322,35 @@ function unacknowledge() {
 
 async function resolve() {
   const id = inc.id;
-  const ok = await confirm({
-    title: 'Resolve this incident?',
-    text: 'Resolving is final. If these alerts fire again they open a new incident, '
-      + 'and if any are still firing this one stays closed regardless. '
-      + 'Use snooze if you only need it out of the way.',
-    confirmLabel: 'Resolve',
-    danger: true,
+  const res = await openSheet(() => {
+    const textarea = h('textarea', {
+      name: 'resolution', autofocus: true, maxlength: '10000',
+      placeholder: 'What fixed it? Optional, shown on the next similar incident.',
+    });
+    const form = h('form', {
+      class: 'sheet-form',
+      onsubmit: (e) => {
+        e.preventDefault();
+        closeSheet({ resolution: textarea.value.trim() });
+      },
+    },
+      h('h2', { class: 'sheet-title', text: 'Resolve this incident?' }),
+      h('p', {
+        text: 'Resolving is final. If these alerts fire again they open a new incident, '
+          + 'and if any are still firing this one stays closed regardless. '
+          + 'Use snooze if you only need it out of the way.',
+      }),
+      textarea,
+      h('div', { class: 'sheet-actions' },
+        h('button', { class: 'btn', type: 'button', onclick: () => closeSheet(null), text: 'Cancel' }),
+        h('button', { class: 'btn btn-danger', type: 'submit', text: 'Resolve' })),
+    );
+    textarea.addEventListener('keydown', (e) => {
+      if (e.key === 'Enter' && (e.ctrlKey || e.metaKey)) form.requestSubmit();
+    });
+    return form;
   });
-  if (ok) await run(() => api.resolve(id), 'Resolved');
+  if (res) await run(() => api.resolve(id, res.resolution), 'Resolved');
 }
 
 function archive() {
@@ -382,16 +428,18 @@ async function addNote() {
     const textarea = h('textarea', {
       name: 'content', required: true, autofocus: true, placeholder: 'What did you find? What did you do?', maxlength: '10000',
     });
+    const fix = h('input', { type: 'checkbox', name: 'fix' });
     const form = h('form', {
       class: 'sheet-form',
       onsubmit: (e) => {
         e.preventDefault();
         const v = textarea.value.trim();
-        if (v) closeSheet(v);
+        if (v) closeSheet({ content: v, pinned: fix.checked });
       },
     },
       h('h2', { class: 'sheet-title', text: 'Add note' }),
       textarea,
+      h('label', { class: 'check' }, fix, ' This is what fixed it (shown on similar incidents)'),
       h('div', { class: 'sheet-actions' },
         h('button', { class: 'btn', type: 'button', onclick: () => closeSheet(null), text: 'Cancel' }),
         h('button', { class: 'btn btn-primary', type: 'submit', text: 'Save note' })),
@@ -402,7 +450,7 @@ async function addNote() {
     });
     return form;
   });
-  if (content) await run(() => api.addNote(id, content), 'Note added');
+  if (content) await run(() => api.addNote(id, content.content, content.pinned), 'Note added');
 }
 
 async function deleteNote(ev) {