Seed type-only Logger surface for HostContract dependency

src/observability/logger/types.ts

@@ -0,0 +1,27 @@
+// Ownership: src/observability/logger/ is owned by Phase 1 sub-plan 1G-logger.
+// This type-only seed exists because Phase 1A-1's HostContract depends on Logger.
+// Sub-plan 1G-logger extends this file with runtime transports.
+
+export type LogLevel = "debug" | "info" | "warn" | "error";
+
+export type LogFields = Record<string, string | number | boolean | null | undefined>;
+
+export interface Logger {
+  debug(msg: string, fields?: LogFields): void;
+  info(msg: string, fields?: LogFields): void;
+  warn(msg: string, fields?: LogFields): void;
+  error(msg: string, fields?: LogFields & { err?: Error }): void;
+  child(context: LogFields): Logger;
+}
+
+export interface LogRecord {
+  ts: string;
+  level: LogLevel;
+  msg: string;
+  fields: LogFields;
+}
+
+export interface LogTransport {
+  write(record: LogRecord): void;
+  flush(): Promise<void>;
+}