04 — Navigation intents end-to-end

Type: AFK Label: ready-for-agent

What to build

The agent gains the ability to navigate the user to internal URLs without requiring approval. Per CONTEXT.md, navigation intents auto-execute (with a toast for transparency) because they touch only client-side state and require no access token.

• Add a navigate tool to Bedrock’s tool definitions with a single url parameter (string, internal-path only — no external URLs in v1).
• Chat service forwards navigate tool-use blocks as NavigationIntent { url } in the streamed response.
• System Prompt Builder gains the navigation-vs-API taxonomy guidance: when the user wants to go somewhere on the site, emit a navigate.
• Navigation Intent Handler (browser): on receipt, calls the SPA router and shows a transient “Taking you to …” toast with an undo affordance (history.back()).
• Browser Turn Orchestrator: handles navigationIntents[] alongside text.

Tests: System Prompt Builder snapshot updated; Agent Loop test for the “text + navigation intent” response shape; Browser Turn Orchestrator reducer test for the navigation event.

Acceptance criteria

• “Take me to billing” sends the user to the billing page with a toast.
• Toast offers an undo that returns the user to the previous page.
• Navigation intents are auto-executed without an approval card.
• External URLs (anything not starting with the app’s own path prefix) are rejected client-side rather than navigated to.
• When the agent emits both streamed text and a navigation intent in one turn, the text renders first and the navigation fires after the text settles.

Blocked by

• 02-bedrock-text-conversation-streaming