fix(kimi-cli): isolate context by running CLI in /tmp to prevent session resume

backend/internal/service/kimi_cli_gateway.go

@@ -77,7 +77,11 @@ func (g *KimiCLIGateway) ForwardChatCompletions(
 	}
 
 	// 4. Run CLI (CLI manages its own OAuth auth via `kimi login`)
+	// Use a temp working directory to prevent kimi-cli from auto-resuming
+	// the last session associated with the backend's working directory.
+	// This ensures each request is stateless and context-isolated.
 	cmd := exec.CommandContext(ctx, g.cliPath, args...)
+	cmd.Dir = "/tmp"
 	cmd.Stdin = strings.NewReader(ndjsonInput)
 
 	stdout, err := cmd.StdoutPipe()