fix(providers): complete OAuth model discovery

docs/configuration.md

@@ -729,6 +729,11 @@ Then run:
 nanobot agent -m "Hello!"
 ```
 
+The WebUI model selector loads the models available to the signed-in account
+from Codex's online catalog. Context-window and reasoning-effort metadata come
+from that response; if discovery is unavailable, nanobot keeps a small built-in
+fallback instead of emptying the selector.
+
 Codex Fast mode can be enabled from the WebUI provider settings, or with:
 
 ```json
@@ -808,6 +813,10 @@ a nanobot update.
 
 GitHub Copilot uses OAuth instead of API keys. Requires a [GitHub account with a plan](https://github.com/features/copilot/plans) configured. No `providers.github_copilot` block is needed in `config.json`; `nanobot provider login` stores the OAuth session outside config.
 
+After login, the WebUI loads the account-specific Copilot model catalog online.
+Only models compatible with nanobot's current Copilot chat-completions transport
+are shown; Responses-only entries are intentionally omitted.
+
 For GitHub Enterprise / Copilot for Business, set the endpoint overrides you need before login:
 ```bash
 export NANOBOT_GITHUB_COPILOT_CLIENT_ID="your-enterprise-client-id"

docs/providers.md

@@ -572,6 +572,10 @@ For OpenAI Codex:
 nanobot provider login openai-codex --set-main
 ```
 
+The WebUI reads the account's Codex model catalog online, including current
+context-window and reasoning-effort metadata. A small compatible catalog remains
+available when the service cannot be reached.
+
 For an eligible X Premium / Grok subscription:
 
 ```bash
@@ -603,6 +607,11 @@ For GitHub Copilot:
 nanobot provider login github-copilot --set-main
 ```
 
+The WebUI reads the models enabled for the signed-in Copilot account. nanobot
+currently lists only entries that support Copilot's chat-completions endpoint;
+models exposed solely through the Responses endpoint stay hidden until that
+wire protocol is supported by the Copilot provider.
+
 Each command authenticates the selected provider and makes its current default model active. OpenAI Codex and eligible GitHub Copilot models participate in [Responses state retention](./configuration.md#responses-state-and-compaction), while native compaction remains provider-capability-specific. OAuth providers are not valid automatic fallbacks. See [`troubleshooting.md`](./troubleshooting.md#provider-and-model-problems) for proxy, headless-login, model-name, and config-key errors.
 
 ## Provider Resolution