feat: Phase 3 model toggle — cycle chat-role slot models in UI

Replaces the role-cycle toggle with a slot model toggle in the Context &
Memory panel. The active model label is shown on the button; clicking cycles
through Primary → Backup 1 → Backup 2 slots configured for the Chat role.

- app.js: remove activeRole()/availableRoles role-cycling; add
  activeChatModel()/chatModels slot cycling; update send/orchestrate
  payloads to send slot + chat_role:"chat"; fix updateSendBtnTitle and
  startRunTimer to use activeChatModel()
- chat.py: add slot field to ChatRequest; pass slot= to complete();
  resolve backend_label from slot config; add _chat_slot_models() helper;
  include chat_models in GET /backend response
- HELP.md: update Model toggle description, tool count (62/16),
  Backends section, API chat payload example

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

cortex/static/HELP.md

@@ -6,7 +6,7 @@
      and are appended automatically by help.html when present.
 -->
 
-*Last updated: 2026-05-09*
+*Last updated: 2026-05-12*
 
 ---
 
@@ -43,7 +43,7 @@ The **Context & Memory** panel (sliders icon with tier number) contains all conf
 | **Context Tier** | T1 – T4 context depth |
 | **Memory Layers** | Toggle Long / Mid / Short memory on/off |
 | **Distill Memory** | Manually trigger Short / Mid / Long / All distillation |
-| **Role** | Active LLM role — click to cycle through configured role assignments |
+| **Model** | Active chat model — click to cycle through your configured slot models (Primary → Backup 1 → …) |
 | **Display** | **Aa** cycles font size · **☾** toggles theme · **S/M/L** cycles input area height · **⌃↵** toggles send shortcut |
 
 All settings persist in `localStorage` across page refreshes.
@@ -82,12 +82,14 @@ Orchestrated sessions persist to history exactly like regular chat.
 
 ### Available Tools
 
-50 tools across 12 categories. Each tool schema is sent to the model on every orchestrated call — fewer active tools means fewer tokens per call.
+62 tools across 16 categories. Each tool schema is sent to the model on every orchestrated call — fewer active tools means fewer tokens per call.
 
 | Category | Tools |
 |---|---|
 | **Web** | `web_search`, `http_fetch`, `web_read`, `http_post` |
-| **Files** | `file_read`, `file_list`, `file_write`, `session_read`, `session_search` |
+| **Project Files** | `project_file_read`, `project_file_list`, `file_stat`, `file_grep`, `file_diff`, `file_syntax_check` |
+| **Files** (admin) | `file_read`, `file_list`, `file_write`, `session_read`, `session_search` |
+| **Git** | `git_status`, `git_log`, `git_diff` |
 | **Shell** | `shell_exec`, `claude_allow_dir` |
 | **System** | `cortex_restart`, `cortex_logs`, `cortex_status`, `cortex_update` |
 | **Tasks** | `task_list`, `task_create`, `task_update`, `task_complete` |
@@ -96,10 +98,12 @@ Orchestrated sessions persist to history exactly like regular chat.
 | **Scratchpad** | `scratch_read`, `scratch_write`, `scratch_append`, `scratch_clear` |
 | **Notifications** | `web_push`, `email_send`, `nc_talk_send`, `nc_talk_history` |
 | **Aether Journals** | `ae_journal_list/search`, `ae_journal_entries_list`, `ae_journal_entry_read/create/update/disable/append/prepend` |
+| **Aether Tasks** | `ae_task_list` |
 | **Agent Notes** | `agent_notes_read`, `agent_notes_write`, `agent_notes_append`, `agent_notes_clear` |
 | **Agents** | `spawn_agent` |
+| **Home Assistant** | `ha_get_state`, `ha_get_states`, `ha_call_service` |
 
-File, Shell, System, Agents, and some Notification/Web tools are **admin-only** and not visible to regular users.
+Files, Shell, System, Agents, and some Notification/Web tools are **admin-only** and not visible to regular users.
 `http_post` requires a URL prefix allowlist in `home/{user}/http_allowlist.json`.
 `nc_talk_history` requires `nc_username` and `nc_app_password` in `channels.json` under `nextcloud`.
 
@@ -149,21 +153,14 @@ Once installed, opening Cortex from the home screen or app launcher skips the br
 
 ## Backends
 
-Three backends are available:
+The **Model** toggle in the Context & Memory panel cycles through the slot models configured for your Chat role (Primary → Backup 1 → Backup 2 → …). Click it to switch between models mid-session.
 
-| Backend | What it is |
-|---|---|
-| **Claude** | Anthropic Claude via the Claude CLI (OAuth — no API key needed) |
-| **Gemini** | Google Gemini via the Gemini CLI |
-| **Local** | Any OpenAI-compatible endpoint (Open WebUI, Ollama, OpenRouter, etc.) |
+- The button label shows the active model (e.g. "GPT-4o", "Gemini 2.5 Flash")
+- The selected slot is sent with each chat request so the correct model is used
+- If only one model is configured, the toggle does nothing
+- A system message appears in the chat when you switch models
 
-The **Role** toggle in the Context & Memory panel cycles through configured role assignments. Each role maps to a Primary / Backup 1 / Backup 2 model chain set in the Model Registry.
-
-- The active model label appears below the toggle button
-- `auto` (default) uses the model assigned to the `chat` role in your Model Registry
-- Forcing a specific backend overrides the role assignment for that session
-
-If the active backend fails, a fallback is tried automatically. A **⚡** badge appears on the response when this happens.
+If the active model fails, the next configured backup slot is tried automatically.
 
 Each response shows a **model tag** (bottom-right of message) with the model label and host, so you always know what responded.
 
@@ -447,10 +444,12 @@ Chat request body (`POST /chat`):
   "message": "string",
   "session_id": "string | null",
   "tier": 2,
-  "model": "claude | gemini | local | null",
+  "chat_role": "chat",
+  "slot": "primary | backup_1 | backup_2 | null",
   "include_long": true,
   "include_mid": true,
-  "include_short": true
+  "include_short": true,
+  "off_record": false
 }
 ```