feat(hermes): Hermes-only mode — run with no Open WebUI server

[cogwheel0]

Summary

Makes Open WebUI optional so a user can install the app and use a self-hosted Hermes Agent exclusively — no OWUI server at all. The mode is derived from what's configured and is switchable anytime; first run shows a backend chooser.

Stacked on feat/hermes-agent (#521) — review that one first; this PR's diff is the Hermes-only delta.

Design — two signals

• preferredBackendProvider (lib/core/providers/backend_mode_providers.dart) — a synchronous, persisted Notifier<PreferredBackend> (unset | owui | hermes). Read by the router only, for boot determinism — mirrors reviewerModeProvider's synchronous role. On cold boot the router runs redirect() while activeServerProvider is still loading and Hermes secrets are still loading, so a purely-derived gate would bounce a Hermes-only user to server-connection. The flag avoids that; real gating stays derived.
• hermesOnlyModeProvider (derived, in hermes_providers.dart) — !reviewerMode && hermesConfig.isUsable && activeServer == null. Drives UI gating; widgets rebuild as it settles.

What's included

• Onboarding: new BackendChooserPage (Connect to Open WebUI / Use a Hermes Agent) + Routes.backendChooser. Reuses HermesSettingsPage(isOnboarding: true) with a "Finish setup" button that validates isUsable, sets preferredBackend = hermes, and enters the app.
• Router: Hermes-only short-circuits straight to chat before any OWUI server/auth branch; holds splash (not server-connection) while Hermes secrets load; first run → chooser. Disabled-Hermes safety net avoids a stuck splash.
• Models: Models.build / defaultModelProvider surface + auto-select the synthetic Hermes model when there's no OWUI API. Send guard relaxed (extracted to a pure isSendBlocked() helper) to allow api == null for Hermes models.
• UI gating: hide chats/notes/terminal/channels across the 3 synchronized tab sites — Hermes becomes the home tab. preferredBackend = owui is set on successful OWUI connect.
• Composer gating: when a Hermes model is active, hide the OWUI affordances — the "+" overflow button, quick pills, and the iOS keyboard-accessory actions (Hermes has no OWUI tools/web-search/image-gen/attachments and uses its own / skills).
• iOS native settings sheet (100% data-driven from Dart, no Swift changes): gate the OWUI account sections (profile, AI memory, data connection, password + profile detail sheets, sign-out) on Hermes-only; render a Hermes-branded profile header (name "Hermes Agent", agent host, hermes_agent.png avatar); the About detail skips the server lookup so it no longer errors with no server.
• Bidirectional switching: a "Connect to Open WebUI" entry in both the native sheet (routed via a control event in main.dart) and the Flutter profile page; the router reaches the OWUI connect/auth routes for a Hermes-only user; preferredBackend resets to unset when a Hermes-only backend is disabled.

Verification

• flutter analyze clean; flutter test (2218) passing — incl. unit tests for preferredBackend parse/persistence, hermesOnlyMode derivation (usable/no-server, server-present, disabled, incomplete, reviewer precedence), isSendBlocked (the send-guard relaxation), and modelsProvider/defaultModelProvider Hermes surfacing + auto-select when api == null.
• On-device E2E (erased iOS simulator, fresh install, live Hermes server): backend chooser → "Use a Hermes Agent" → enter URL/key (capabilities + toolsets load) → Finish → lands in Hermes-only chat (header "Hermes Agent", no model dropdown) → sidebar shows only the Hermes tab → kill/relaunch boots straight into Hermes chat (boot determinism) → send created a new server-side session with no OWUI backend.

Note

Add Hermes-only mode to run without an Open WebUI server

• Introduces a preferredBackendProvider that persists whether the user has chosen Open WebUI or a Hermes Agent as their backend, read synchronously at boot.
• Adds a /backend-chooser onboarding screen that lets first-time users pick between the two backends, replacing the previous direct redirect to /server-connection.
• When Hermes is the preferred backend and no Open WebUI server is configured, the router sends users directly to /chat; the sidebar hides Chats, Notes, Terminal, and Channels tabs; and the profile sheet replaces account options with a 'Connect to Open WebUI' entry.
• modelsProvider and defaultModelProvider now surface and auto-select a synthetic Hermes model when no OpenWebUI API is available, and message send/regenerate are unblocked for Hermes models without an API.
• The Hermes settings page gains an onboarding mode (triggered via GoRouter state.extra) that auto-enables Hermes, hides the toggle, and routes to chat on completion.
• Behavioral Change: users with no configured server are now redirected to /backend-chooser instead of /server-connection.

📊 Macroscope summarized 821a735. 17 files reviewed, 0 issues evaluated, 0 issues filtered, 0 comments posted

🗂️ Filtered Issues

No issues evaluated.

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[macroscopeapp]

🟠 High

conduit/lib/features/chat/providers/chat_providers.dart

Line 4215 in 821a735

final session = await api!.sendMessageSession(

regenerateMessage passes the isSendBlocked guard for Hermes models with api == null, but then unconditionally calls api!.sendMessageSession(...) at line 4215. This throws a null assertion error in Hermes-only mode because the function lacks the Hermes dispatch path that _sendMessageInternal uses. Consider adding Hermes transport routing before the OpenWebUI API call.

🚀 Reply "fix it for me" or copy this AI Prompt for your agent:

In file @lib/features/chat/providers/chat_providers.dart around line 4215:

`regenerateMessage` passes the `isSendBlocked` guard for Hermes models with `api == null`, but then unconditionally calls `api!.sendMessageSession(...)` at line 4215. This throws a null assertion error in Hermes-only mode because the function lacks the Hermes dispatch path that `_sendMessageInternal` uses. Consider adding Hermes transport routing before the OpenWebUI API call.

[macroscopeapp]

🟢 Low widgets/sidebar_user_pill.dart:37

The data.buffer.asUint8List() call ignores the ByteData offset and length, so if the underlying buffer is larger than the asset, the returned Uint8List includes extra trailing bytes that corrupt the cached avatar image. Consider passing data.offsetInBytes and data.lengthInBytes to asUint8List to return only the exact asset bytes.

Suggested change

	return _hermesAvatarBytesCache = data.buffer.asUint8List();
	return _hermesAvatarBytesCache = data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes);

🚀 Reply "fix it for me" or copy this AI Prompt for your agent:

In file @lib/features/navigation/widgets/sidebar_user_pill.dart around line 37:

The `data.buffer.asUint8List()` call ignores the `ByteData` offset and length, so if the underlying buffer is larger than the asset, the returned `Uint8List` includes extra trailing bytes that corrupt the cached avatar image. Consider passing `data.offsetInBytes` and `data.lengthInBytes` to `asUint8List` to return only the exact asset bytes.

[macroscopeapp]

🟢 Low views/hermes_settings_page.dart:48

After the two await calls (setEnabled and ensureSessionKey), ref.read(preferredBackendProvider.notifier) on line 49 accesses ref on a potentially disposed ConsumerState, which throws. The if (!mounted) return check on line 52 only guards context.go but comes after the unsafe ref.read. Add a mounted check before line 49 to guard that access as well.

 await notifier.ensureSessionKey();
+    if (!mounted) return;
     await ref

🚀 Reply "fix it for me" or copy this AI Prompt for your agent:

In file @lib/features/hermes/views/hermes_settings_page.dart around lines 48-49:

After the two `await` calls (`setEnabled` and `ensureSessionKey`), `ref.read(preferredBackendProvider.notifier)` on line 49 accesses `ref` on a potentially disposed `ConsumerState`, which throws. The `if (!mounted) return` check on line 52 only guards `context.go` but comes after the unsafe `ref.read`. Add a `mounted` check before line 49 to guard that access as well.