diff --git a/scripts/tui-host.no-jest.ts b/scripts/tui-host.no-jest.ts
index 24e80bc5..907d90c3 100644
--- a/scripts/tui-host.no-jest.ts
+++ b/scripts/tui-host.no-jest.ts
@@ -54,7 +54,8 @@ async function main() {
   const projectId = process.env.PROJECT_ID!;
 
   // Which program to drive — PROGRAM env from the workbench e2e runner;
-  // defaults to the integration flow. getProgramConfig throws on unknown ids.
+  // defaults to the integration flow. getProgramConfig throws and names the id
+  // when PROGRAM holds a typo.
   const programId = (process.env.PROGRAM ||
     Program.PostHogIntegration) as ProgramId;
   const programConfig = getProgramConfig(programId);
diff --git a/src/lib/programs/__tests__/program-registry.test.ts b/src/lib/programs/__tests__/program-registry.test.ts
index 4a1baa37..2b1f8804 100644
--- a/src/lib/programs/__tests__/program-registry.test.ts
+++ b/src/lib/programs/__tests__/program-registry.test.ts
@@ -4,6 +4,7 @@ import {
   getProgramConfig,
   getSubcommandPrograms,
 } from '@lib/programs/program-registry';
+import type { ProgramId } from '@lib/programs/program-registry';
 import type { WizardSession } from '@lib/wizard-session';
 
 describe('PROGRAM_REGISTRY', () => {
@@ -27,6 +28,15 @@ describe('getProgramConfig', () => {
       'revenue-analytics',
     );
   });
+
+  it('throws a named error for an unknown id', () => {
+    // A string-sourced id (e.g. a mistyped PROGRAM env var) reaches this
+    // function via a cast. It must name the bad id here, not crash opaquely
+    // deeper in the pipeline.
+    expect(() => getProgramConfig('does-not-exist' as ProgramId)).toThrow(
+      /does-not-exist/,
+    );
+  });
 });
 
 describe('getSubcommandPrograms', () => {
diff --git a/src/lib/programs/program-registry.ts b/src/lib/programs/program-registry.ts
index 2633c295..eb969c76 100644
--- a/src/lib/programs/program-registry.ts
+++ b/src/lib/programs/program-registry.ts
@@ -118,12 +118,24 @@ export const Program = {
 export type ProgramId = (typeof PROGRAM_REGISTRY)[number]['id'];
 
 /**
- * Look up a program config by its id. `ProgramId` is a union of every
- * registered id, so the lookup is statically guaranteed to find a match
- * — the `!` is a load-bearing assertion of that invariant, not a hope.
+ * Look up a program config by its id, throwing when the id is unknown.
+ *
+ * `ProgramId` is meant to be the union of every registered id, but because
+ * `ProgramConfig.id` is typed `string` the union collapses to `string` — so
+ * the parameter type does not statically reject an unknown id. The runtime
+ * check below is the real guard: it names the bad id when a caller passes an
+ * untyped string (e.g. a mistyped env var), so a typo fails loudly here
+ * instead of surfacing as an opaque crash deeper in the pipeline.
  */
 export function getProgramConfig(id: ProgramId): ProgramConfig {
-  return PROGRAM_REGISTRY.find((c) => c.id === id)!;
+  const config = PROGRAM_REGISTRY.find((c) => c.id === id);
+  if (!config) {
+    const known = PROGRAM_REGISTRY.map((c) => c.id).join(', ');
+    throw new Error(
+      `Unknown program id "${id}". Registered program ids: ${known}.`,
+    );
+  }
+  return config;
 }
 
 /** A program config that is exposed as a CLI subcommand. */
diff --git a/src/lib/runners/run-wizard.ts b/src/lib/runners/run-wizard.ts
index 262c5f56..4a374018 100644
--- a/src/lib/runners/run-wizard.ts
+++ b/src/lib/runners/run-wizard.ts
@@ -101,8 +101,7 @@ export function runWizard(
         return;
       }
 
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      tui = startTUI(WIZARD_VERSION, config.id as any);
+      tui = startTUI(WIZARD_VERSION, config.id);
       const activeTui = tui;
 
       const session = buildSession({