Refactor AI Assist to background-task + buffer architecture

The assist flow previously tied the entire LLM generation to a single
POST request with no keepalives, causing NS_ERROR_NET_PARTIAL_TRANSFER
in Firefox when Hypercorn closed the connection during gaps between
chunks. This refactor decouples generation into a background task with
a buffer and a separate SSE stream — the same pattern used by chat.

- generation_buffer.py: Widen _buffers to support string keys, add
  create/get/remove_assist_buffer() using "assist:{user_id}" keys,
  fix cleanup log format for string keys
- generation_task.py: Add run_assist_generation() — lightweight
  background task with no DB persistence or title generation
- notes.py: Replace single POST SSE route with POST /api/notes/assist
  (returns 202) + GET /api/notes/assist/stream (SSE with 15s keepalives
  and Last-Event-ID reconnection); 409 if already running
- useAssist.ts: Switch from apiStreamPost to apiPost + apiSSEStream
  two-step pattern with named event mapping and stream handle cleanup

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/composables/useAssist.ts

@@ -1,5 +1,5 @@
 import { ref, computed, watch, type Ref } from "vue";
-import { apiStreamPost } from "@/api/client";
+import { apiPost, apiSSEStream, type SSEStreamHandle } from "@/api/client";
 import { useChatStore } from "@/stores/chat";
 import {
   parseMarkdownSections,
@@ -28,6 +28,7 @@ export function useAssist(body: Ref<string>) {
 
   // Snapshot of body at the time a section/selection was chosen
   let bodySnapshot = "";
+  let streamHandle: SSEStreamHandle | null = null;
 
   const target = computed<AssistTarget | null>(() => {
     if (customSelection.value) {
@@ -79,6 +80,10 @@ export function useAssist(body: Ref<string>) {
   }
 
   function clearSelection() {
+    if (streamHandle) {
+      streamHandle.close();
+      streamHandle = null;
+    }
     selectedSection.value = null;
     customSelection.value = null;
     instruction.value = "";
@@ -97,28 +102,33 @@ export function useAssist(body: Ref<string>) {
     error.value = "";
 
     try {
-      await apiStreamPost(
-        "/api/notes/assist",
-        {
-          body: body.value,
-          target_section: target.value.text,
-          instruction: instruction.value,
-        },
-        (data) => {
-          if (data.chunk) {
-            streamingText.value += data.chunk as string;
-          }
-          if (data.done) {
-            proposedText.value = (data.full_text as string) || streamingText.value;
-            state.value = "review";
-          }
-          if (data.error) {
-            error.value = data.error as string;
-            state.value = "idle";
-          }
+      // Step 1: Launch background generation
+      await apiPost("/api/notes/assist", {
+        body: body.value,
+        target_section: target.value.text,
+        instruction: instruction.value,
+      });
+
+      // Step 2: Tail the SSE buffer
+      streamHandle = apiSSEStream("/api/notes/assist/stream", (evt) => {
+        if (evt.event === "chunk") {
+          streamingText.value += evt.data.chunk as string;
         }
-      );
-      // If stream ended without a done event, use accumulated text
+        if (evt.event === "done") {
+          proposedText.value = (evt.data.full_text as string) || streamingText.value;
+          state.value = "review";
+          streamHandle = null;
+        }
+        if (evt.event === "error") {
+          error.value = evt.data.error as string;
+          state.value = "idle";
+          streamHandle = null;
+        }
+      });
+
+      await streamHandle.done;
+
+      // Fallback: if stream ended without done/error, use accumulated text
       if (state.value === "streaming") {
         if (streamingText.value) {
           proposedText.value = streamingText.value;
@@ -126,10 +136,12 @@ export function useAssist(body: Ref<string>) {
         } else {
           state.value = "idle";
         }
+        streamHandle = null;
       }
     } catch (e) {
       error.value = e instanceof Error ? e.message : "Request failed";
       state.value = "idle";
+      streamHandle = null;
     }
   }
 

src/fabledassistant/routes/notes.py

@@ -1,4 +1,4 @@
-import json
+import asyncio
 import logging
 from datetime import date
 
@@ -7,7 +7,12 @@ from quart import Blueprint, Response, jsonify, request
 from fabledassistant.auth import login_required, get_current_user_id
 from fabledassistant.config import Config
 from fabledassistant.services.assist import build_assist_messages
-from fabledassistant.services.llm import stream_chat
+from fabledassistant.services.generation_buffer import (
+    GenerationState,
+    create_assist_buffer,
+    get_assist_buffer,
+)
+from fabledassistant.services.generation_task import run_assist_generation
 from fabledassistant.services.notes import (
     convert_note_to_task,
     convert_task_to_note,
@@ -191,7 +196,7 @@ async def get_backlinks_route(note_id: int):
 @notes_bp.route("/assist", methods=["POST"])
 @login_required
 async def assist_route():
-    """Stream an AI-assisted section edit via SSE."""
+    """Launch a background assist generation task."""
     uid = get_current_user_id()
     data = await request.get_json()
 
@@ -202,22 +207,50 @@ async def assist_route():
     if not target_section or not instruction:
         return jsonify({"error": "target_section and instruction are required"}), 400
 
+    # Reject if an assist generation is already running for this user
+    existing = get_assist_buffer(uid)
+    if existing and existing.state == GenerationState.RUNNING:
+        return jsonify({"error": "Assist generation already running"}), 409
+
     model = await get_setting(uid, "default_model", Config.OLLAMA_MODEL)
     messages = build_assist_messages(body, target_section, instruction)
 
-    async def generate():
-        full_text = ""
-        try:
-            async for chunk in stream_chat(messages, model):
-                full_text += chunk
-                yield f"data: {json.dumps({'chunk': chunk})}\n\n"
-            yield f"data: {json.dumps({'done': True, 'full_text': full_text})}\n\n"
-        except Exception as e:
-            logger.exception("Assist generation failed")
-            yield f"data: {json.dumps({'error': str(e)})}\n\n"
+    buf = create_assist_buffer(uid)
+    asyncio.create_task(run_assist_generation(buf, messages, model))
+
+    return jsonify({"status": "started"}), 202
+
+
+@notes_bp.route("/assist/stream", methods=["GET"])
+@login_required
+async def assist_stream_route():
+    """SSE endpoint that tails the assist generation buffer."""
+    uid = get_current_user_id()
+
+    buf = get_assist_buffer(uid)
+    if buf is None:
+        return jsonify({"error": "No active assist generation"}), 404
+
+    last_id_str = request.headers.get("Last-Event-ID") or request.args.get("last_event_id")
+    last_id = int(last_id_str) if last_id_str is not None else -1
+
+    async def stream():
+        cursor = last_id
+        while True:
+            pending = buf.events_after(cursor)
+            for event in pending:
+                yield buf.format_sse(event)
+                cursor = event.index
+
+            if buf.state != GenerationState.RUNNING:
+                break
+
+            got_new = await buf.wait_for_event(cursor, timeout=15.0)
+            if not got_new:
+                yield ": keepalive\n\n"
 
     return Response(
-        generate(),
+        stream(),
         content_type="text/event-stream",
         headers={
             "Cache-Control": "no-cache",

src/fabledassistant/services/generation_buffer.py

@@ -70,7 +70,7 @@ class GenerationBuffer:
 
 
 # Module-level singleton registry
-_buffers: dict[int, GenerationBuffer] = {}
+_buffers: dict[int | str, GenerationBuffer] = {}
 _cleanup_task: asyncio.Task | None = None
 _GRACE_PERIOD = 60.0  # seconds to keep completed buffers
 
@@ -92,20 +92,38 @@ def remove_buffer(conv_id: int) -> None:
     _buffers.pop(conv_id, None)
 
 
+def create_assist_buffer(user_id: int) -> GenerationBuffer:
+    key = f"assist:{user_id}"
+    existing = _buffers.get(key)
+    if existing and existing.state == GenerationState.RUNNING:
+        raise RuntimeError(f"Assist generation already running for user {user_id}")
+    buf = GenerationBuffer(conversation_id=0, assistant_message_id=0)
+    _buffers[key] = buf
+    return buf
+
+
+def get_assist_buffer(user_id: int) -> GenerationBuffer | None:
+    return _buffers.get(f"assist:{user_id}")
+
+
+def remove_assist_buffer(user_id: int) -> None:
+    _buffers.pop(f"assist:{user_id}", None)
+
+
 async def _cleanup_loop() -> None:
     """Remove completed/errored buffers after grace period."""
     while True:
         await asyncio.sleep(15)
         now = time.monotonic()
         to_remove = [
-            cid for cid, buf in _buffers.items()
+            key for key, buf in _buffers.items()
             if buf.state != GenerationState.RUNNING
             and buf.finished_at is not None
             and now - buf.finished_at > _GRACE_PERIOD
         ]
-        for cid in to_remove:
-            _buffers.pop(cid, None)
-            logger.debug("Cleaned up generation buffer for conversation %d", cid)
+        for key in to_remove:
+            _buffers.pop(key, None)
+            logger.debug("Cleaned up generation buffer for key %s", key)
 
 
 def start_cleanup_loop() -> None:

src/fabledassistant/services/generation_task.py

@@ -134,3 +134,25 @@ async def run_generation(
         buf.state = GenerationState.ERRORED
         buf.finished_at = time.monotonic()
         buf.append_event("error", {"error": str(e)})
+
+
+async def run_assist_generation(
+    buf: GenerationBuffer,
+    messages: list[dict],
+    model: str,
+) -> None:
+    """Stream LLM response for assist into buffer. No DB persistence."""
+    try:
+        async for chunk in stream_chat(messages, model, options={"num_predict": 4096}):
+            buf.content_so_far += chunk
+            buf.append_event("chunk", {"chunk": chunk})
+
+        buf.state = GenerationState.COMPLETED
+        buf.finished_at = time.monotonic()
+        buf.append_event("done", {"done": True, "full_text": buf.content_so_far})
+
+    except Exception as e:
+        logger.exception("Error in assist generation task")
+        buf.state = GenerationState.ERRORED
+        buf.finished_at = time.monotonic()
+        buf.append_event("error", {"error": str(e)})

summary.md

@@ -12,7 +12,7 @@
 >    Include file-level details in the commit body when the change is non-trivial.
 
 ## Last Updated
-2026-02-12 — Phase 5.3: Registration Control, User Management, Security Hardening
+2026-02-13 — Phase 5.6: Assist Background-Task + Buffer Architecture
 
 ## Project Overview
 Fabled Assistant is a self-hosted note-taking and task-tracking application with
@@ -66,6 +66,9 @@ for AI-assisted features.
   tail the buffer and can reconnect mid-stream without data loss. Buffer has
   `cancel_event` for user-initiated stop. Completed buffers are cleaned up after
   60s grace period. Periodic DB flushes every 5s preserve partial content.
+  Both chat and AI Assist use this architecture — assist buffers are keyed by
+  `"assist:{user_id}"` (string keys) instead of conversation ID (int keys).
+  Assist generation has no DB persistence, no title generation, no cancellation.
 - **SSE over WebSockets for LLM streaming:** SSE clients connect via
   `GET /api/chat/conversations/:id/generation/stream` with `Last-Event-ID`
   reconnection support. Frontend uses `fetch()` + `ReadableStream`. Simpler than
@@ -175,6 +178,18 @@ for AI-assisted features.
 - `to_dict()` returns: `id`, `title`, `model`, `message_count`, `created_at`, `updated_at`
 - `list_conversations()` uses a subquery for `message_count` instead of eager-loading all messages
 
+### App Logs
+- `id` (int PK), `category` (text NOT NULL — `audit`/`usage`/`error`),
+  `user_id` (int FK users ON DELETE SET NULL), `username` (text — denormalized),
+  `action` (text), `endpoint` (text), `method` (text), `status_code` (int),
+  `duration_ms` (real), `ip_address` (text), `details` (text — JSON-serialized),
+  `created_at` (timestamptz DEFAULT now())
+- Single table with `category` field for all log types
+- Denormalized `username` preserves attribution after user deletion
+- `details` stores flexible JSON data (error tracebacks, audit metadata, etc.)
+- Indexes: `category`, `user_id`, `created_at`, composite `(category, created_at DESC)`
+- Automatic retention cleanup via hourly asyncio task (configurable `LOG_RETENTION_DAYS`, default 90)
+
 ### Messages
 - `id` (int PK), `conversation_id` (FK to conversations, CASCADE), `role` (str: system/user/assistant),
   `content` (str), `status` (str, default `'complete'` — `complete`/`generating`/`error`),
@@ -203,7 +218,8 @@ fabledassistant/
 │       ├── 0006_add_settings_table.py # Settings key-value table
 │       ├── 0007_add_title_and_updated_at_indexes.py # B-tree indexes on notes.title and conversations.updated_at
 │       ├── 0008_add_users_and_user_id.py # Users table, user_id FKs on notes/conversations/settings, composite PK for settings
-│       └── 0009_add_message_status.py   # Add status column to messages table (default 'complete')
+│       ├── 0009_add_message_status.py   # Add status column to messages table (default 'complete')
+│       └── 0010_add_app_logs_table.py  # App logs table for audit, usage, and error logging
 ├── src/
 │   └── fabledassistant/
 │       ├── __init__.py
@@ -215,7 +231,8 @@ fabledassistant/
 │       │   ├── user.py          # User model (id, username, email, password_hash, role, created_at)
 │       │   ├── note.py          # Note model (unified: id, title, body, tags[], parent_id, user_id, status, priority, due_date, timestamps)
 │       │   ├── conversation.py  # Conversation + Message models with user_id
-│       │   └── setting.py       # Setting model (composite PK: user_id + key, value TEXT)
+│       │   ├── setting.py       # Setting model (composite PK: user_id + key, value TEXT)
+│       │   └── app_log.py      # AppLog model (id, category, user_id, username, action, endpoint, method, status_code, duration_ms, ip_address, details, created_at)
 │       ├── routes/
 │       │   ├── __init__.py
 │       │   ├── api.py           # /api blueprint with /health endpoint (public)
@@ -231,9 +248,12 @@ fabledassistant/
 │       │   ├── notes.py         # CRUD with user_id isolation, is_task filter, convert, backlinks, search_notes_for_context
 │       │   ├── llm.py           # Ollama interaction: build_context with user_id, streaming, URL fetching
 │       │   ├── chat.py          # Conversation CRUD with user_id isolation, add_message, save/summarize as note (LLM-titled, chat-tagged)
-│       │   ├── generation_buffer.py # In-memory SSE event buffer with cancel_event, reconnect support, auto-cleanup
-│       │   ├── generation_task.py   # Background asyncio task: streams LLM into buffer, periodic DB flush, LLM title generation
-│       │   └── settings.py      # Settings CRUD with user_id isolation: get_setting, set_setting, set_settings_batch, get_all_settings
+│       │   ├── generation_buffer.py # In-memory SSE event buffer with cancel_event, reconnect support, auto-cleanup; supports chat (int keys) and assist (string keys)
+│       │   ├── generation_task.py   # Background asyncio tasks: run_generation (chat, DB flush, titles) + run_assist_generation (lightweight, no DB)
+│       │   ├── settings.py      # Settings CRUD with user_id isolation: get_setting, set_setting, set_settings_batch, get_all_settings
+│       │   ├── logging.py      # App logging: log_audit, log_usage, log_error, get_logs, get_log_stats, delete_old_logs, start_log_retention_loop
+│       │   ├── email.py        # SMTP email service: get_smtp_config, is_smtp_configured, send_email, send_test_email
+│       │   └── notifications.py # Notification service: notify_security_event, check_due_tasks, start_notification_loop
 │       ├── utils/
 │       │   ├── __init__.py
 │       │   └── tags.py          # extract_tags() — regex #tag extraction, skips code fences
@@ -248,11 +268,11 @@ fabledassistant/
     │   ├── assets/
     │   │   └── theme.css        # CSS custom properties: light/dark themes, body reset, design tokens, responsive breakpoints (480/768/1024), utility classes (.hide-mobile/.hide-desktop), mobile touch targets
     │   ├── api/
-    │   │   └── client.ts        # ApiError class, apiGet/apiPost/apiPut/apiPatch/apiDelete + apiSSEStream (EventSource-based), auto 401→login redirect
+    │   │   └── client.ts        # ApiError class, apiGet/apiPost/apiPut/apiPatch/apiDelete + apiSSEStream (fetch+ReadableStream), apiStreamPost (legacy), auto 401→login redirect
     │   ├── composables/
     │   │   ├── useTheme.ts      # Theme toggle, localStorage, prefers-color-scheme
     │   │   ├── useAutocomplete.ts # Legacy textarea autocomplete (replaced by Tiptap suggestion extensions)
-    │   │   └── useAssist.ts     # AI Assist composable: section parsing, target selection, LLM streaming, accept/reject; watches body ref for auto-sync
+    │   │   └── useAssist.ts     # AI Assist composable: section parsing, target selection, two-step POST+SSE streaming (apiPost → apiSSEStream), accept/reject; watches body ref for auto-sync
     │   ├── stores/
     │   │   ├── auth.ts          # Auth state: user, isAuthenticated, isAdmin, login/register/logout/checkAuth
     │   │   ├── notes.ts         # CRUD + tag filter, resolveTitle, convertToTask, convertToNote, fetchBacklinks, fetchAllTags (with toast errors)
@@ -290,7 +310,8 @@ fabledassistant/
     │   │   ├── TaskEditorView.vue # Create/edit task: Tiptap editor, sticky toolbar, AI Assist panel, Ctrl+S, dirty guard
     │   │   └── TaskViewerView.vue # Task detail: rendered markdown, badges, convert-to-note, backlinks
     │   ├── components/
-    │   │   ├── AppHeader.vue    # Nav bar: brand, nav links, status indicator, theme toggle, user info + logout, hamburger menu (mobile)
+    │   │   ├── LogsView.vue     # Admin log viewer: stats summary, category/search/date filters, paginated table with expandable detail rows
+    │   │   ├── AppHeader.vue    # Nav bar: brand, nav links (incl. admin Logs), status indicator, theme toggle, user info + logout, hamburger menu (mobile)
     │   │   ├── ChatPanel.vue    # Slide-out chat panel (right side overlay, receives contextNoteId prop), bubble-style messages, floating dark input, note picker, context pills with promote/exclude
     │   │   ├── ChatMessage.vue  # Message bubble: markdown rendering, configurable assistant name label, "Save as Note" action on assistant messages
     │   │   ├── NoteCard.vue     # Card with rendered markdown preview (v-html), TagPill, tag-click emit
@@ -305,7 +326,7 @@ fabledassistant/
     │   │   ├── PaginationBar.vue # Prev/next + page numbers
     │   │   └── ToastNotification.vue # Fixed-position toast container with close button, warning support
     │   └── router/
-    │       └── index.ts         # Routes: /, /login, /register, /notes/*, /tasks/*, /chat, /chat/:id, /settings, /admin/users; beforeEach auth guard
+    │       └── index.ts         # Routes: /, /login, /register, /notes/*, /tasks/*, /chat, /chat/:id, /settings, /admin/users, /admin/logs; beforeEach auth guard
     └── public/
 ```
 
@@ -326,6 +347,8 @@ fabledassistant/
 | DELETE | `/api/admin/users/:id` | Delete a user (admin only, cannot delete self) |
 | GET | `/api/admin/registration` | Get registration open/closed status (admin only) |
 | PUT | `/api/admin/registration` | Toggle registration open/closed (admin only, body: `{open: bool}`) |
+| GET | `/api/admin/logs` | List log entries (admin only, params: `category`, `user_id`, `search`, `date_from`, `date_to`, `limit`, `offset`) |
+| GET | `/api/admin/logs/stats` | Get log category counts (admin only) |
 | GET | `/api/notes` | List notes (params: `q`, `tag`, `sort`, `order`, `limit`, `offset`; defaults to `is_task=false` — plain notes only; `?is_task=true` for tasks, `?all=true` for everything) |
 | POST | `/api/notes` | Create note (body: `{title, body, status?, priority?, due_date?}` — tags auto-extracted) |
 | GET | `/api/notes/tags` | List all tags from notes table (param: `q` for filter) |
@@ -337,6 +360,8 @@ fabledassistant/
 | POST | `/api/notes/:id/convert-to-task` | Set `status='todo'`, `priority='none'` on note (returns 200) |
 | POST | `/api/notes/:id/convert-to-note` | Clear `status`, `priority`, `due_date` from note (returns 200) |
 | GET | `/api/notes/:id/backlinks` | List notes/tasks that reference this note via wikilinks |
+| POST | `/api/notes/assist` | Launch background assist generation, return 202 (body: `{body, target_section, instruction}`; 409 if already running) |
+| GET | `/api/notes/assist/stream` | SSE endpoint tailing assist generation buffer; supports `Last-Event-ID` reconnection; emits `chunk`, `done`, `error` events with 15s keepalives |
 | GET | `/api/tasks` | List tasks (params: `q`, `tag`, `status`, `priority`, `sort`, `order`, `limit`, `offset`) — queries notes where `status IS NOT NULL` |
 | POST | `/api/tasks` | Create task (body: `{title, body, status?, priority?, due_date?}` — accepts `description` as fallback for `body`) |
 | GET | `/api/tasks/:id` | Get single task |
@@ -357,6 +382,9 @@ fabledassistant/
 | GET | `/api/chat/models` | List available Ollama models |
 | POST | `/api/chat/models/pull` | Pull/download a model from Ollama via SSE streaming progress (body: `{model}`, response: SSE with `{status, completed, total}` events) |
 | POST | `/api/chat/models/delete` | Delete a model from Ollama (body: `{model}`) |
+| GET | `/api/admin/smtp` | Get SMTP config (password masked) (admin only) |
+| PUT | `/api/admin/smtp` | Save SMTP config to admin settings (admin only, body: `{smtp_host, smtp_port, ...}`) |
+| POST | `/api/admin/smtp/test` | Send test email (admin only, body: `{recipient}`) |
 | GET | `/api/settings` | Get all app settings as `{key: value}` dict |
 | PUT | `/api/settings` | Update settings (body: `{key: value, ...}`) |
 
@@ -369,7 +397,7 @@ container startup.
 
 ### Migration Chain
 ```
-0001_create_notes_table.py  →  0002_create_tasks_table.py  →  0003_task_note_companion.py  →  0004_merge_tasks_into_notes.py  →  0005_add_chat_tables.py  →  0006_add_settings_table.py  →  0007_add_title_and_updated_at_indexes.py  →  0008_add_users_and_user_id.py  →  0009_add_message_status.py
+0001_create_notes_table.py  →  0002_create_tasks_table.py  →  0003_task_note_companion.py  →  0004_merge_tasks_into_notes.py  →  0005_add_chat_tables.py  →  0006_add_settings_table.py  →  0007_add_title_and_updated_at_indexes.py  →  0008_add_users_and_user_id.py  →  0009_add_message_status.py  →  0010_add_app_logs_table.py
 ```
 
 ### How Migrations Run
@@ -609,6 +637,34 @@ When adding a new migration, follow these conventions:
 - [x] **Password change:** `PUT /api/auth/password` endpoint + Settings UI section
 - [x] **Production deployment docs:** README documents reverse proxy, rate limiting, CSP headers, SECRET_KEY, registration behavior
 
+### Phase 5.4 — Application Logging System ✓
+- [x] **Single `app_logs` table:** Unified audit/usage/error logging with `category` field
+- [x] **Usage logging middleware:** `after_request` logs all `/api/*` requests with user, endpoint, method, status, duration (skips `/api/admin/logs` to avoid recursion)
+- [x] **Error logging:** `handle_500` captures error type, message, and traceback
+- [x] **Audit logging:** Security events logged in auth routes (register, login, login_failed, logout, password_change) and admin routes (backup, restore, user_delete, registration_toggle)
+- [x] **Denormalized username:** Preserves attribution after user deletion (`user_id` FK uses `ON DELETE SET NULL`)
+- [x] **Admin log viewer:** `/admin/logs` with stats summary, category/search/date filters, paginated table with expandable JSON detail rows
+- [x] **Log stats endpoint:** `GET /api/admin/logs/stats` returns category counts
+- [x] **Configurable retention:** `LOG_RETENTION_DAYS` env var (default 90), hourly asyncio cleanup task
+- [x] **Config:** `LOG_RETENTION_DAYS` added to `Config` class
+
+### Phase 5.5 — SMTP Email Notifications ✓
+- [x] **SMTP email service:** `aiosmtplib` for async email sending, supports STARTTLS (587) and implicit TLS (465)
+- [x] **SMTP config in DB:** Admin configures SMTP via Settings UI, stored in `settings` table; env var fallbacks for Docker Swarm bootstrap
+- [x] **Admin SMTP endpoints:** `GET/PUT /api/admin/smtp` for config management, `POST /api/admin/smtp/test` for sending test emails
+- [x] **Security alert notifications:** Fire-and-forget `asyncio.create_task()` on login, failed login, logout, password change
+- [x] **Task due date reminders:** Hourly background loop checks for due/overdue tasks, sends grouped email per user; dedup via `app_logs` check
+- [x] **Per-user notification preferences:** `notify_task_reminders` and `notify_security_alerts` settings (default enabled)
+- [x] **Settings UI:** Notifications section for all users (checkbox toggles), SMTP section for admin (2-column grid + test email)
+
+### Phase 5.6 — Assist Background-Task + Buffer Architecture ✓
+- [x] **Assist buffer helpers:** `create_assist_buffer()`, `get_assist_buffer()`, `remove_assist_buffer()` using `"assist:{user_id}"` string keys in shared `_buffers` registry
+- [x] **`run_assist_generation()`:** Lightweight background task — streams from Ollama into buffer, no DB persistence, no title generation, no cancellation
+- [x] **Two-step assist API:** `POST /api/notes/assist` returns 202 + launches background task; `GET /api/notes/assist/stream` SSE endpoint tails buffer with 15s keepalives and `Last-Event-ID` reconnection
+- [x] **409 conflict guard:** Rejects concurrent assist requests per user
+- [x] **Frontend two-step pattern:** `useAssist.ts` calls `apiPost()` then `apiSSEStream()` with named event mapping (`chunk`/`done`/`error`); tracks stream handle for cleanup
+- [x] **Fixes `NS_ERROR_NET_PARTIAL_TRANSFER`:** Keepalive pings prevent browser/Hypercorn from closing connection during gaps between LLM chunks
+
 ### Future / Stretch
 - Tagging/labeling system with LLM-suggested tags
 - Calendar/timeline view for tasks
@@ -624,7 +680,7 @@ When adding a new migration, follow these conventions:
 - To reset database: `docker compose down -v && docker compose up --build`
 
 ## Current Status
-**Phase:** Phase 5.3 complete. Registration Control, User Management, Security Hardening.
+**Phase:** Phase 5.6 complete. Assist Background-Task + Buffer Architecture.
 - Full note-taking and task-tracking CRUD with markdown, wikilinks, backlinks, tags
 - **Tiptap WYSIWYG editor** with inline formatting preview, markdown round-trip, paste handling
 - **Tag/wikilink autocomplete** via `@tiptap/suggestion` with heading disambiguation
@@ -632,7 +688,7 @@ When adding a new migration, follow these conventions:
 - **Multi-user authentication** with session cookies, bcrypt passwords, admin role
 - **Per-user data isolation** across notes, conversations, and settings
 - LLM chat via Ollama with background generation task + SSE streaming
-- **AI Assist panel** pinned to bottom 1/3 of editor viewport with auto-syncing sections
+- **AI Assist panel** pinned to bottom 1/3 of editor viewport with auto-syncing sections; uses background-task + buffer architecture with keepalive SSE (same pattern as chat)
 - Note-aware context: auto-includes current note + searches related notes by keyword
 - Context pills with promote/exclude controls; note picker in chat input
 - Save assistant messages as notes (LLM-titled, chat-tagged); summarize conversations as notes
@@ -644,4 +700,10 @@ When adding a new migration, follow these conventions:
 - **App-wide layout fix**: navbar always visible, all views fit within viewport
 - **Responsive design**: hamburger menu, mobile touch targets, responsive breakpoints
 - **Docker Swarm production stack** with secrets, network isolation, health checks, resource limits
+- **Application logging**: audit (security events), usage (API requests), error (unhandled exceptions)
+- **Admin log viewer**: `/admin/logs` with stats, filters, pagination, expandable detail rows
+- **Automatic log retention**: configurable via `LOG_RETENTION_DAYS` (default 90 days)
+- **SMTP email notifications**: security alerts (login/logout/failed login/password change), task due date reminders
+- **Admin SMTP configuration**: Settings UI with test email, DB-stored config with env var fallbacks
+- **Per-user notification preferences**: toggle task reminders and security alerts independently
 - Dark/light theme with CSS custom properties and design tokens