feat(security): AES-256-GCM at-rest encryption for encounters and memories

Extends the existing crypto helper (already used for audio backups and the
Nextcloud token) to cover every column that can hold PHI:

- saved_encounters.transcript, .generated_note, .partial_data
- user_memories.content (templates + Dragon-style corrections)
- user_memories.name (auto-derived from original snippet on corrections,
  so effectively PHI)

Reads decrypt transparently. Legacy plaintext rows continue to work —
decryptString passes non-enc1: values through unchanged — so no migration
is required; rows re-encrypt on their next save.

The encounters list query previously used LEFT(transcript, 200) for a
preview. With ciphertext that slice is meaningless, so the route now
fetches the full columns, decrypts in Node, then slices. At 7-day auto-
delete the row count is bounded and the cost is a handful of GCM
decrypts per list call.

user_memories ORDER BY moved from (category, name) to (category, id)
since SQL can no longer order on encrypted names.

Closes the HHS breach-notification safe-harbor gap on at-rest PHI.

src/routes/encounters.js

@@ -7,17 +7,46 @@ var router = express.Router();
 var db = require('../db/database');
 var { authMiddleware } = require('../middleware/auth');
 var logger = require('../utils/logger');
+var cryptoUtil = require('../utils/crypto');
 
 router.use(authMiddleware);
 
+// Normalise partial_data to a string before encrypting so JSON objects and
+// raw strings round-trip identically. Decryption returns the original string.
+function partialToString(partial_data) {
+  if (partial_data == null) return '{}';
+  if (typeof partial_data === 'object') return JSON.stringify(partial_data);
+  return partial_data;
+}
+
 // ── GET all saved encounters for current user ────────────────────────────
 router.get('/encounters/saved', async function(req, res) {
   try {
+    // transcript/generated_note are encrypted at rest, so we can't slice on
+    // the server with LEFT(..,200). Fetch full columns, decrypt in Node, then
+    // preview. With a 7-day auto-delete the row count is small; the cost is
+    // a handful of AES-GCM decrypts per list call.
     var rows = await db.all(
-      "SELECT id, label, enc_type, status, created_at, updated_at, expires_at, LEFT(transcript, 200) as transcript_preview, LEFT(generated_note, 200) as note_preview FROM saved_encounters WHERE user_id = $1 AND expires_at > NOW() ORDER BY updated_at DESC",
+      "SELECT id, label, enc_type, status, created_at, updated_at, expires_at, transcript, generated_note FROM saved_encounters WHERE user_id = $1 AND expires_at > NOW() ORDER BY updated_at DESC",
       [req.user.id]
     );
-    res.json({ success: true, encounters: rows });
+    var out = rows.map(function (r) {
+      var t = '', n = '';
+      try { t = cryptoUtil.decryptString(r.transcript) || ''; } catch (e) {}
+      try { n = cryptoUtil.decryptString(r.generated_note) || ''; } catch (e) {}
+      return {
+        id: r.id,
+        label: r.label,
+        enc_type: r.enc_type,
+        status: r.status,
+        created_at: r.created_at,
+        updated_at: r.updated_at,
+        expires_at: r.expires_at,
+        transcript_preview: t.substring(0, 200),
+        note_preview: n.substring(0, 200)
+      };
+    });
+    res.json({ success: true, encounters: out });
   } catch (e) { logger.error('GET /encounters/saved', e.message); res.status(500).json({ error: 'Request failed' }); }
 });
 
@@ -29,6 +58,9 @@ router.get('/encounters/saved/:id', async function(req, res) {
       [req.params.id, req.user.id]
     );
     if (!row) return res.status(404).json({ error: 'Encounter not found or expired' });
+    try { row.transcript      = cryptoUtil.decryptString(row.transcript); }      catch (e) {}
+    try { row.generated_note  = cryptoUtil.decryptString(row.generated_note); }  catch (e) {}
+    try { row.partial_data    = cryptoUtil.decryptString(row.partial_data); }    catch (e) {}
     logger.audit(req.user.id, 'encounter_load', 'Loaded encounter: ' + (row.label || 'unlabeled') + ' (id:' + req.params.id + ')', req, { category: 'clinical' });
     res.json({ success: true, encounter: row });
   } catch (e) { logger.error('GET /encounters/saved/:id', e.message); res.status(500).json({ error: 'Request failed' }); }
@@ -57,9 +89,9 @@ router.post('/encounters/saved', async function(req, res) {
         'UPDATE saved_encounters SET label=$1, transcript=$2, generated_note=$3, partial_data=$4, status=$5, version=$6, updated_at=NOW() WHERE id=$7 AND user_id=$8 AND (version = $9 OR $9::int IS NULL)',
         [
           label || 'Untitled',
-          transcript || '',
+          cryptoUtil.encryptString(transcript || ''),
-          generated_note || '',
+          cryptoUtil.encryptString(generated_note || ''),
-          typeof partial_data === 'object' ? JSON.stringify(partial_data) : (partial_data || '{}'),
+          cryptoUtil.encryptString(partialToString(partial_data)),
           status || 'active',
           newVersion,
           id, req.user.id,
@@ -95,9 +127,9 @@ router.post('/encounters/saved', async function(req, res) {
             'UPDATE saved_encounters SET label=$1, transcript=$2, generated_note=$3, partial_data=$4, status=$5, updated_at=NOW() WHERE id=$6 AND user_id=$7',
             [
               label || 'Untitled',
-              transcript || '',
+              cryptoUtil.encryptString(transcript || ''),
-              generated_note || '',
+              cryptoUtil.encryptString(generated_note || ''),
-              typeof partial_data === 'object' ? JSON.stringify(partial_data) : (partial_data || '{}'),
+              cryptoUtil.encryptString(partialToString(partial_data)),
               status || 'active',
               dup.id, req.user.id
             ]
@@ -113,9 +145,9 @@ router.post('/encounters/saved', async function(req, res) {
           req.user.id,
           label || 'Untitled',
           enc_type || 'encounter',
-          transcript || '',
+          cryptoUtil.encryptString(transcript || ''),
-          generated_note || '',
+          cryptoUtil.encryptString(generated_note || ''),
-          typeof partial_data === 'object' ? JSON.stringify(partial_data) : (partial_data || '{}'),
+          cryptoUtil.encryptString(partialToString(partial_data)),
           status || 'active',
           idempotency_key || null,
           autoDeleteDays

src/routes/memories.js

@@ -7,9 +7,19 @@ var router = express.Router();
 var db = require('../db/database');
 var { authMiddleware } = require('../middleware/auth');
 var logger = require('../utils/logger');
+var cryptoUtil = require('../utils/crypto');
 
 router.use(authMiddleware);
 
+// Decrypt a row's user-facing fields. Safe against legacy plaintext rows —
+// cryptoUtil.decryptString passes through values without the "enc1:" prefix.
+function decryptMemory(row) {
+  if (!row) return row;
+  try { row.name    = cryptoUtil.decryptString(row.name); }    catch (e) {}
+  try { row.content = cryptoUtil.decryptString(row.content); } catch (e) {}
+  return row;
+}
+
 var VALID_CATEGORIES = [
   'physical_exam', 'ros', 'encounter_format', 'family_history', 'assessment_plan', 'custom',
   'template_soap', 'template_hpi', 'template_wellvisit', 'template_sickvisit',
@@ -19,10 +29,13 @@ var VALID_CATEGORIES = [
 // ── GET all memories for current user ───────────────────────────────────
 router.get('/memories', async function(req, res) {
   try {
+    // Cannot ORDER BY encrypted `name`; order by id as a stable proxy after
+    // per-category sort. Frontend can re-sort alphabetically client-side.
     var rows = await db.all(
-      'SELECT id, category, name, content, created_at, updated_at FROM user_memories WHERE user_id = $1 ORDER BY category, name',
+      'SELECT id, category, name, content, created_at, updated_at FROM user_memories WHERE user_id = $1 ORDER BY category, id',
       [req.user.id]
     );
+    rows.forEach(decryptMemory);
     res.json({ success: true, memories: rows });
   } catch (e) { logger.error('GET /memories', e.message); res.status(500).json({ error: 'Request failed' }); }
 });
@@ -41,7 +54,12 @@ router.post('/memories', async function(req, res) {
 
     var result = await db.run(
       'INSERT INTO user_memories (user_id, category, name, content) VALUES ($1,$2,$3,$4)',
-      [req.user.id, cat, name.trim().substring(0, 100), content.trim().substring(0, 5000)]
+      [
+        req.user.id,
+        cat,
+        cryptoUtil.encryptString(name.trim().substring(0, 100)),
+        cryptoUtil.encryptString(content.trim().substring(0, 5000))
+      ]
     );
     res.json({ success: true, id: result.lastInsertRowid });
   } catch (e) { logger.error('POST /memories', e.message); res.status(500).json({ error: 'Request failed' }); }
@@ -55,9 +73,9 @@ router.put('/memories/:id', async function(req, res) {
     await db.run(
       'UPDATE user_memories SET name=$1, category=$2, content=$3, updated_at=NOW() WHERE id=$4 AND user_id=$5',
       [
-        (name || '').trim().substring(0, 100),
+        cryptoUtil.encryptString((name || '').trim().substring(0, 100)),
         cat,
-        (content || '').trim().substring(0, 5000),
+        cryptoUtil.encryptString((content || '').trim().substring(0, 5000)),
         req.params.id,
         req.user.id
       ]
@@ -82,6 +100,7 @@ router.get('/memories/context', async function(req, res) {
       [req.user.id]
     );
     if (rows.length === 0) return res.json({ success: true, context: '' });
+    rows.forEach(decryptMemory);
 
     var templates = [];
     var corrections = [];
@@ -153,7 +172,7 @@ router.post('/memories/correction', async function(req, res) {
 
     await db.run(
       'INSERT INTO user_memories (user_id, category, name, content) VALUES ($1,$2,$3,$4)',
-      [req.user.id, cat, name, content]
+      [req.user.id, cat, cryptoUtil.encryptString(name), cryptoUtil.encryptString(content)]
     );
     res.json({ success: true });
   } catch (e) { logger.error('POST /memories/correction', e.message); res.status(500).json({ error: 'Request failed' }); }