feat: update NewConversationParams to take an optional model_provider

[bolinfest]

An AppServer client should be able to use any (model_provider, model) in the user's config. NewConversationParams already supported specifying the model, but this PR expands it to support model_provider, as well.

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• feat: introduce GetConversationSummary RPC #5803
• -> feat: update NewConversationParams to take an optional model_provider #5793

[chatgpt-codex-connector]

💡 Codex Review

codex/codex-rs/core/src/rollout/list.rs

Lines 359 to 380 in 1cfea37

	struct ProviderMatcher<'a> {
	filters: &'a [String],
	matches_openai: bool,
	}
	impl<'a> ProviderMatcher<'a> {
	fn new(filters: &'a [String]) -> Option<Self> {
	if filters.is_empty() {
	return None;
	}
	let matches_openai = filters.iter().any(|provider| provider == "openai");
	Some(Self {
	filters,
	matches_openai,
	})
	}
	fn matches(&self, session_provider: Option<&str>) -> bool {
	match session_provider {
	Some(provider) => self.filters.iter().any(|candidate| candidate == provider),
	None => self.matches_openai,

Default filter drops older non‑OpenAI sessions

The provider matcher treats a missing model_provider as matching only when the filter contains "openai". Because the app server now defaults ListConversations to filter on the current provider, any sessions recorded before this field existed (which therefore have model_provider = null) will vanish from the list whenever the configured provider is something other than OpenAI. Users who recorded Anthropic or other provider sessions before this change will have no way to discover or resume them unless they manually pass an empty filter. Consider treating None as the active provider or bypassing provider filtering when metadata is absent.

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