Send context signals in routing predict request

[aashna]

Add RoutingContextSignals interface with optional fields (has_image, chat_location, turn_number, session_id, previous_model, reference_count, prompt_char_count) and spread them into the router request body.

AutomodeService populates signals from the ChatRequest context before each routing call.

[Copilot]

Pull request overview

This PR extends the auto-mode model routing request payload with additional context signals derived from the current ChatRequest, enabling the router service to make more informed decisions.

Changes:

• Added a RoutingContextSignals interface and included its fields in the router prediction request body.
• Populated routing context signals in AutomodeService (location, session id, references, prompt length, previous model, turn number).
• Added a helper to serialize ChatLocation to a string value for routing.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

File	Description
src/platform/endpoint/node/routerDecisionFetcher.ts	Adds RoutingContextSignals and spreads them into the router request body; extends getRouterDecision signature.
src/platform/endpoint/node/automodeService.ts	Builds and passes RoutingContextSignals from ChatRequest data; adds chatRequestLocationToString helper.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (1)

src/platform/endpoint/node/automodeService.ts:300

• The cache’s turnCount is incremented unconditionally on every call, even when routing is skipped due to unchanged prompt or router-disabled cases. If turnCount is meant to represent user turns for routing signals, it should be updated only when advancing to a new turn; otherwise it will drift over time (and affect future turn_number values).

		this._autoModelCache.set(conversationId, { endpoint: autoEndpoint, tokenBank, lastSessionToken: token.session_token, lastRoutedPrompt, turnCount: (entry?.turnCount ?? 0) + 1 });
		return autoEndpoint;