Add runtime aliases and validate --runtime flag

Consolidate duplicate RUNTIME_CONFIGS entries (debugpy, lldb-dap) into
an alias map so canonical runtime names stay unique. Unknown --runtime
values now fail fast with a list of available runtimes instead of
silently spawning a broken DAP session.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: waltoss

src/dap/runtimes/index.ts

@@ -7,13 +7,32 @@ export type { DapAttachArgs, DapLaunchArgs, DapRuntimeConfig, UserLaunchInput }
 
 const RUNTIME_CONFIGS: Record<string, DapRuntimeConfig> = {
 	lldb: lldbConfig,
-	"lldb-dap": lldbConfig,
 	codelldb: codelldbConfig,
 	python: debugpyConfig,
-	debugpy: debugpyConfig,
 	java: javaConfig,
 };
 
+/** Maps alias names to their canonical runtime name. */
+const RUNTIME_ALIASES: Record<string, keyof typeof RUNTIME_CONFIGS> = {
+	jdwp: "java",
+	debugpy: "python",
+	"lldb-dap": "lldb"
+};
+
+/**
+ * Resolves a runtime alias to its canonical name.
+ * Returns the input unchanged if it is not an alias.
+ */
+export function resolveRuntime(runtime: string): string {
+	return RUNTIME_ALIASES[runtime] ?? runtime;
+}
+
+/** Set of all known DAP runtime names (canonical + aliases). */
+export const KNOWN_DAP_RUNTIMES = new Set([
+	...Object.keys(RUNTIME_CONFIGS),
+	...Object.keys(RUNTIME_ALIASES),
+]);
+
 const DEFAULT_CONFIG: DapRuntimeConfig = {
 	getAdapterCommand: () => {
 		throw new Error("Unknown runtime");

src/session/factory.ts

@@ -1,27 +1,39 @@
 import { CdpSession } from "../cdp/session.ts";
+import { KNOWN_DAP_RUNTIMES, resolveRuntime } from "../dap/runtimes/index.ts";
 import { DapSession } from "../dap/session.ts";
 import type { Logger } from "../logger/index.ts";
 import type { Session } from "./session.ts";
 
-const DAP_RUNTIMES = new Set(["lldb", "lldb-dap", "codelldb", "python", "debugpy", "java"]);
+const CDP_RUNTIMES = new Set(["node", "bun"]);
 
 /**
  * Returns true if the given runtime string should use a DAP session
  * (as opposed to the default CDP session for Node.js/Bun).
  */
 export function isDapRuntime(runtime: string | undefined): runtime is string {
-	if (runtime === undefined || runtime === "node" || runtime === "bun") return false;
-	return DAP_RUNTIMES.has(runtime) || !["node", "bun"].includes(runtime);
+	if (runtime === undefined || CDP_RUNTIMES.has(runtime)) return false;
+	return KNOWN_DAP_RUNTIMES.has(runtime);
 }
 
+/** All runtime names accepted by --runtime (CDP + DAP + aliases). */
+const ALL_RUNTIMES = new Set([...CDP_RUNTIMES, ...KNOWN_DAP_RUNTIMES]);
+
 /**
  * Create the appropriate Session implementation for the given runtime.
+ * Resolves aliases (e.g. "jdwp" → "java") and rejects unknown runtimes.
  */
 export function createSession(
 	sessionName: string,
 	runtime: string | undefined,
 	options?: { logger?: Logger<"daemon"> },
 ): Session {
+	if (runtime !== undefined) {
+		if (!ALL_RUNTIMES.has(runtime)) {
+			const available = [...ALL_RUNTIMES].sort().join(", ");
+			throw new Error(`Unknown runtime "${runtime}". Available: ${available}`);
+		}
+		runtime = resolveRuntime(runtime);
+	}
 	if (isDapRuntime(runtime)) {
 		return new DapSession(sessionName, runtime, options);
 	}