Why

/status was showing the configured ModelProviderInfo.base_url for Amazon Bedrock, which can be stale or misleading because the actual Bedrock Mantle endpoint is derived at runtime from the resolved AWS region. This made sessions report the wrong provider endpoint even though requests used the correct runtime URL.

What changed

• Added ModelProvider::runtime_base_url() so provider implementations can expose the request-time base URL through the shared runtime provider abstraction.
• Moved Bedrock region-to-Mantle URL resolution into amazon_bedrock::mantle::runtime_base_url(), keeping region resolution private to the Mantle module.
• Overrode runtime_base_url() for Amazon Bedrock so it returns the resolved Mantle endpoint instead of the configured default.
• Resolved and cached the runtime provider base URL during TUI startup, then used that cached value when rendering /status.
• Added status coverage that verifies Bedrock displays the runtime URL and ignores the configured Bedrock base_url when they differ.

Verification

model provider is resolved correctly in local build: