diff --git a/decisions/PRACTICES.md b/decisions/PRACTICES.md
index e3ece71..6af5987 100644
--- a/decisions/PRACTICES.md
+++ b/decisions/PRACTICES.md
@@ -13,9 +13,9 @@ The repository has two test layers with a runner each. They cover different code
 
 ### Pi extension (bun)
 
-- Tests run with `bun test` and live beside the code they cover, as `*.test.ts` in `extensions/dld-run/`. Pi loads only `index.ts` from an extension directory, so colocated tests are never loaded as extensions.
+- Tests run with `bun test` and live beside the code they cover, as `*.test.ts` in `extensions/pi-dld-run/`. Pi loads only `index.ts` from an extension directory, so colocated tests are never loaded as extensions.
 - The extension is typechecked with `npx tsc --noEmit`, which requires `npm install` for the pi type definitions. Typecheck is part of the definition of done, not an optional extra — it is the only mechanism that catches a drift between our assumptions and the real pi API.
-- Tests exercise the extension through the fake in `extensions/dld-run/testing/fake-pi.ts`, never a live harness.
+- Tests exercise the extension through the fake in `extensions/pi-dld-run/testing/fake-pi.ts`, never a live harness.
 - The fake's surface is declared with `Pick<ExtensionAPI, ...>` and assigned without type assertions, so the compiler rejects a fake that no longer matches pi. Do not reach for `as` to silence a mismatch — it converts a compile error into a runtime `TypeError`. Where a partial object genuinely cannot be typed (a context object standing in for a large interface), confine the assertion and comment why.
 - Prefer dependency injection over module-level side effects, so failure branches are reachable from tests. A check that can only read the real filesystem can only ever be tested in the happy case.
 
diff --git a/extensions/dld-core/run-state.test.ts b/extensions/dld-core/run-state.test.ts
index c10d4ec..55b7b33 100644
--- a/extensions/dld-core/run-state.test.ts
+++ b/extensions/dld-core/run-state.test.ts
@@ -9,7 +9,7 @@ import {
 	readRunFrom,
 	type RunState,
 } from "./run-state.ts";
-import { createFakePi } from "../dld-run/testing/fake-pi.ts";
+import { createFakePi } from "../pi-dld-run/testing/fake-pi.ts";
 
 let workspace: string;
 
diff --git a/extensions/dld-run/doctor.test.ts b/extensions/pi-dld-run/doctor.test.ts
similarity index 100%
rename from extensions/dld-run/doctor.test.ts
rename to extensions/pi-dld-run/doctor.test.ts
diff --git a/extensions/dld-run/doctor.ts b/extensions/pi-dld-run/doctor.ts
similarity index 100%
rename from extensions/dld-run/doctor.ts
rename to extensions/pi-dld-run/doctor.ts
diff --git a/extensions/dld-run/index.ts b/extensions/pi-dld-run/index.ts
similarity index 100%
rename from extensions/dld-run/index.ts
rename to extensions/pi-dld-run/index.ts
diff --git a/extensions/dld-run/loop.test.ts b/extensions/pi-dld-run/loop.test.ts
similarity index 100%
rename from extensions/dld-run/loop.test.ts
rename to extensions/pi-dld-run/loop.test.ts
diff --git a/extensions/dld-run/loop.ts b/extensions/pi-dld-run/loop.ts
similarity index 100%
rename from extensions/dld-run/loop.ts
rename to extensions/pi-dld-run/loop.ts
diff --git a/extensions/dld-run/package.test.ts b/extensions/pi-dld-run/package.test.ts
similarity index 95%
rename from extensions/dld-run/package.test.ts
rename to extensions/pi-dld-run/package.test.ts
index 7c57db7..7888a1a 100644
--- a/extensions/dld-run/package.test.ts
+++ b/extensions/pi-dld-run/package.test.ts
@@ -34,7 +34,7 @@ describe("pi package manifest", () => {
 	test("the extension entry point is where pi looks for it", () => {
 		// Pi loads only index.ts from an extension subdirectory, which is what
 		// keeps colocated *.test.ts files from being loaded as extensions.
-		expect(existsSync(join(packageRoot(), "extensions", "dld-run", "index.ts"))).toBe(true);
+		expect(existsSync(join(packageRoot(), "extensions", "pi-dld-run", "index.ts"))).toBe(true);
 	});
 
 	test("pi runtime packages are optional peers, never bundled", () => {
diff --git a/extensions/dld-run/surfaces.test.ts b/extensions/pi-dld-run/surfaces.test.ts
similarity index 100%
rename from extensions/dld-run/surfaces.test.ts
rename to extensions/pi-dld-run/surfaces.test.ts
diff --git a/extensions/dld-run/testing/fake-pi.test.ts b/extensions/pi-dld-run/testing/fake-pi.test.ts
similarity index 100%
rename from extensions/dld-run/testing/fake-pi.test.ts
rename to extensions/pi-dld-run/testing/fake-pi.test.ts
diff --git a/extensions/dld-run/testing/fake-pi.ts b/extensions/pi-dld-run/testing/fake-pi.ts
similarity index 100%
rename from extensions/dld-run/testing/fake-pi.ts
rename to extensions/pi-dld-run/testing/fake-pi.ts