fix(adapter): handle Anthropic-compat gateways without /v1/ in base URL

src/adapter/adapters/anthropic/adapter_impl.rs

@@ -193,7 +193,29 @@ impl Adapter for AnthropicAdapter {
 	fn get_service_url(_model: &ModelIden, service_type: ServiceType, endpoint: Endpoint) -> Result<String> {
 		let base_url = endpoint.base_url();
 		let url = match service_type {
-			ServiceType::Chat | ServiceType::ChatStream => format!("{base_url}messages"),
+			ServiceType::Chat | ServiceType::ChatStream => {
+				// Normalize the base URL to always have `/v1/messages` regardless
+				// of whether the caller passed `https://api.anthropic.com/v1/`
+				// (with trailing slash), `https://api.anthropic.com/v1`
+				// (no slash), or a custom gateway like
+				// `https://api.minimax.io/anthropic/v1` where the `/v1` is the
+				// version segment and `messages` should be appended with a
+				// slash separator. Previously this used
+				// `format!("{base_url}messages")` which produced malformed URLs
+				// like `https://api.minimax.io/anthropic/v1messages` (404).
+				if base_url.ends_with("messages") {
+					base_url.to_string()
+				} else if base_url.ends_with("/v1/") {
+					// Legacy Anthropic shape: trailing slash already present, just append messages.
+					format!("{base_url}messages")
+				} else if base_url.ends_with("/v1") {
+					// Version segment without trailing slash — need a slash separator.
+					format!("{base_url}/messages")
+				} else {
+					// No version segment; append the canonical /v1/messages.
+					format!("{}/v1/messages", base_url.trim_end_matches('/'))
+				}
+			}
 			ServiceType::Embed => format!("{base_url}embeddings"), // Anthropic doesn't support embeddings yet
 		};
 
@@ -943,6 +965,77 @@ mod tests {
 		let result = parse_cache_creation_details(&cache_creation);
 		assert!(result.is_none());
 	}
+
+	// region:    --- Endpoint URL normalization tests
+	//
+	// Regression tests for the bug where `format!("{base_url}messages")` produced
+	// malformed URLs (e.g. `https://api.minimax.io/anthropicmessages`) for
+	// Anthropic-compat gateways whose base URL didn't end in `/v1/`. The fix
+	// added a three-way shape detection in `get_service_url`.
+
+	const TEST_BASE_URL: &str = "https://api.anthropic.com/v1/";
+
+	fn make_url(base_url: &str, service_type: ServiceType) -> String {
+		let endpoint = Endpoint::from_owned(base_url.to_string());
+		AnthropicAdapter::get_service_url(
+			&ModelIden::new(AdapterKind::Anthropic, "claude-3-5-haiku-latest".to_string()),
+			service_type,
+			endpoint,
+		)
+		.unwrap()
+	}
+
+	#[test]
+	fn anthropic_default_base_url_produces_canonical_v1_messages() {
+		// The default Anthropic base URL ends with `/v1/` (trailing slash).
+		// Verify the canonical output is `…/v1/messages`.
+		let url = make_url(TEST_BASE_URL, ServiceType::Chat);
+		assert_eq!(url, "https://api.anthropic.com/v1/messages");
+	}
+
+	#[test]
+	fn anthropic_base_url_with_v1_no_trailing_slash_works() {
+		// Some gateways (e.g. terraphim-llm-proxy's MiniMax provider after
+		// the 2026-08-11 config fix) pass `…/v1` without a trailing slash.
+		// We must insert a `/` separator so the path is `/v1/messages` rather
+		// than `/v1messages` (which 404s).
+		let url = make_url("https://api.minimax.io/anthropic/v1", ServiceType::Chat);
+		assert_eq!(url, "https://api.minimax.io/anthropic/v1/messages");
+	}
+
+	#[test]
+	fn anthropic_base_url_without_version_segment_gets_v1_messages_suffix() {
+		// A bare host (no `/v1/`, no `/v1`) should get `/v1/messages` appended
+		// with a proper `/` separator. This was the broken case that produced
+		// `https://api.minimax.io/anthropicmessages` before this fix.
+		let url = make_url("https://api.minimax.io/anthropic", ServiceType::Chat);
+		assert_eq!(url, "https://api.minimax.io/anthropic/v1/messages");
+	}
+
+	#[test]
+	fn anthropic_base_url_with_trailing_slash_without_version_gets_v1_messages() {
+		// A bare host with a trailing slash should also work — `/v1/messages`
+		// appended after stripping the trailing `/`.
+		let url = make_url("https://api.minimax.io/", ServiceType::Chat);
+		assert_eq!(url, "https://api.minimax.io/v1/messages");
+	}
+
+	#[test]
+	fn anthropic_base_url_already_ending_in_messages_passes_through() {
+		// Defensive: if a caller already passed a fully-formed URL ending in
+		// `messages`, return it unchanged.
+		let url = make_url("https://api.minimax.io/anthropic/v1/messages", ServiceType::Chat);
+		assert_eq!(url, "https://api.minimax.io/anthropic/v1/messages");
+	}
+
+	#[test]
+	fn anthropic_streaming_path_uses_same_url_construction_as_chat() {
+		// Streaming should use identical URL logic as Chat.
+		let url = make_url("https://api.minimax.io/anthropic", ServiceType::ChatStream);
+		assert_eq!(url, "https://api.minimax.io/anthropic/v1/messages");
+	}
+
+	// endregion: --- Endpoint URL normalization tests
 }
 
 // endregion: --- Tests

src/webc/web_stream.rs

@@ -255,17 +255,13 @@ fn new_with_pretty_json_array(
 						last_idx = idx + 1;
 					}
 				}
-				'[' => {
-					if depth == 0 {
-						messages.push("[".to_string());
-						last_idx = idx + 1;
-					}
+				'[' if depth == 0 => {
+					messages.push("[".to_string());
+					last_idx = idx + 1;
 				}
-				']' => {
-					if depth == 0 {
-						messages.push("]".to_string());
-						last_idx = idx + 1;
-					}
+				']' if depth == 0 => {
+					messages.push("]".to_string());
+					last_idx = idx + 1;
 				}
 				_ => {
 					// Ignore other characters outside of objects (whitespace, commas)