diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index 656466b16..f7d1311e2 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -90,6 +90,9 @@
 ### Fixed
 
 - Fixed `/context` counting hidden, explicit-only skills (`hide: true` / `disable-model-invocation`) in the Skills category and subtracting that inflated estimate from the first system-prompt block, which reported `System prompt: 0 tokens` and inflated Skills usage. Accounting now counts only the skills actually rendered into the system prompt — mirroring `buildSystemPrompt`'s filter, so hidden skills and all skills when the `read` tool is unavailable contribute zero ([#6498](https://github.com/can1357/oh-my-pi/issues/6498)).
+### Fixed
+
+- Fixed `pi-sprite` failing plugin validation because the legacy Pi compatibility shims omitted `createExtensionRuntime` and terminal capability/image-deletion helpers used by the extension ([#6506](https://github.com/can1357/oh-my-pi/issues/6506)).
 
 ## [17.1.1] - 2026-07-24
 
diff --git a/packages/coding-agent/src/extensibility/legacy-pi-coding-agent-shim.ts b/packages/coding-agent/src/extensibility/legacy-pi-coding-agent-shim.ts
index b2a7be365..6d2040124 100644
--- a/packages/coding-agent/src/extensibility/legacy-pi-coding-agent-shim.ts
+++ b/packages/coding-agent/src/extensibility/legacy-pi-coding-agent-shim.ts
@@ -861,6 +861,11 @@ export interface ResourceLoader {
 	readonly __ompLegacyPiLoader?: true;
 }
 
+/** Create a pre-initialization runtime for legacy extension resource loaders. */
+export function createExtensionRuntime(): ExtensionRuntime {
+	return new ExtensionRuntime();
+}
+
 /**
  * Loader-owned inputs that {@link createAgentSession} needs regardless of
  * whether the caller provided extra options. `cwd`/`agentDir` fall back to
@@ -894,7 +899,7 @@ export class DefaultResourceLoader implements ResourceLoader {
 	readonly __ompLegacyPiLoader = true as const;
 	#state: ResolvedLoaderState;
 	#options: DefaultResourceLoaderOptions;
-	#extensionsResult: LoadExtensionsResult = { extensions: [], errors: [], runtime: new ExtensionRuntime() };
+	#extensionsResult: LoadExtensionsResult = { extensions: [], errors: [], runtime: createExtensionRuntime() };
 	#skills: Skill[] = [];
 	#skillDiagnostics: ResourceDiagnostic[] = [];
 	#prompts: PromptTemplate[] = [];
@@ -1043,7 +1048,7 @@ export class DefaultResourceLoader implements ResourceLoader {
 		const { cwd, noExtensions, additionalExtensionPaths, extensionFactories, eventBus } = this.#state;
 
 		if (noExtensions && additionalExtensionPaths.length === 0 && extensionFactories.length === 0) {
-			return { extensions: [], errors: [], runtime: new ExtensionRuntime() };
+			return { extensions: [], errors: [], runtime: createExtensionRuntime() };
 		}
 
 		const paths = await discoverSessionExtensionPaths(
diff --git a/packages/coding-agent/src/extensibility/legacy-pi-tui-shim.ts b/packages/coding-agent/src/extensibility/legacy-pi-tui-shim.ts
index 4ac5f57fd..7b448933a 100644
--- a/packages/coding-agent/src/extensibility/legacy-pi-tui-shim.ts
+++ b/packages/coding-agent/src/extensibility/legacy-pi-tui-shim.ts
@@ -6,5 +6,31 @@
  * exposes the equivalent, broader `decodePrintableKey` helper. Keep the legacy
  * name available without reintroducing it into the canonical package surface.
  */
+import { ImageProtocol, isInsideTmux, TERMINAL, wrapTmuxPassthrough } from "@oh-my-pi/pi-tui";
+
 export * from "@oh-my-pi/pi-tui";
-export { decodePrintableKey as decodeKittyPrintable } from "@oh-my-pi/pi-tui";
+export {
+	decodePrintableKey as decodeKittyPrintable,
+	encodeKittyDeleteImage as deleteKittyImage,
+} from "@oh-my-pi/pi-tui";
+
+/** Report canonical terminal capabilities through the legacy Pi TUI shape. */
+export function getCapabilities(): {
+	images: "kitty" | "iterm2" | null;
+	trueColor: boolean;
+	hyperlinks: boolean;
+} {
+	const images =
+		TERMINAL.imageProtocol === ImageProtocol.Kitty
+			? "kitty"
+			: TERMINAL.imageProtocol === ImageProtocol.Iterm2
+				? "iterm2"
+				: null;
+	return { images, trueColor: TERMINAL.trueColor, hyperlinks: TERMINAL.hyperlinks };
+}
+
+/** Delete every Kitty graphics image using the legacy Pi TUI control sequence. */
+export function deleteAllKittyImages(): string {
+	const sequence = "\x1b_Ga=d,d=A,q=2\x1b\\";
+	return isInsideTmux() ? wrapTmuxPassthrough(sequence) : sequence;
+}
diff --git a/packages/coding-agent/test/extensibility/legacy-pi-ai-type-remap.test.ts b/packages/coding-agent/test/extensibility/legacy-pi-ai-type-remap.test.ts
index a26a02eb4..90ebf4d6b 100644
--- a/packages/coding-agent/test/extensibility/legacy-pi-ai-type-remap.test.ts
+++ b/packages/coding-agent/test/extensibility/legacy-pi-ai-type-remap.test.ts
@@ -265,6 +265,28 @@ describe("legacy pi package root remaps (issue #1474)", () => {
 		expect(loaded.printable).toBe("a");
 	});
 
+	it("loads pi-sprite's legacy terminal helpers", async () => {
+		const entry = await writeFixtureExtension(
+			[
+				'import { deleteAllKittyImages, deleteKittyImage, getCapabilities } from "@earendil-works/pi-tui";',
+				"export const deleteOne = deleteKittyImage(42);",
+				"export const deleteAll = deleteAllKittyImages();",
+				"export const capabilities = getCapabilities();",
+			].join("\n"),
+		);
+
+		const loaded = (await loadLegacyPiModule(entry)) as {
+			deleteOne: string;
+			deleteAll: string;
+			capabilities: { images: "kitty" | "iterm2" | null; trueColor: boolean; hyperlinks: boolean };
+		};
+		expect(loaded.deleteOne).toContain("a=d,d=I,i=42,q=2");
+		expect(loaded.deleteAll).toContain("a=d,d=A,q=2");
+		expect(["kitty", "iterm2", null]).toContain(loaded.capabilities.images);
+		expect(typeof loaded.capabilities.trueColor).toBe("boolean");
+		expect(typeof loaded.capabilities.hyperlinks).toBe("boolean");
+	});
+
 	it("preserves legacy defineTool root imports and usable coding tools", async () => {
 		const dir = await fs.mkdtemp(path.join(os.tmpdir(), "omp-legacy-coding-tools-"));
 		tempRoots.push(dir);
diff --git a/packages/coding-agent/test/extensibility/legacy-pi-inplace-load.test.ts b/packages/coding-agent/test/extensibility/legacy-pi-inplace-load.test.ts
index d84c2dc3f..0fb021b89 100644
--- a/packages/coding-agent/test/extensibility/legacy-pi-inplace-load.test.ts
+++ b/packages/coding-agent/test/extensibility/legacy-pi-inplace-load.test.ts
@@ -850,6 +850,45 @@ describe("legacy-pi in-place module loading (issue #1674)", () => {
 		});
 	});
 
+	it("exposes a fresh legacy extension runtime through the package root", async () => {
+		const dir = await writePackage({
+			"package.json": JSON.stringify({ name: "legacy-extension-runtime-ext", version: "1.0.0" }),
+			"index.ts": [
+				'import { createExtensionRuntime } from "@earendil-works/pi-coding-agent";',
+				"const first = createExtensionRuntime();",
+				"const second = createExtensionRuntime();",
+				"first.flagValues.set('sprite', true);",
+				"let initializationError;",
+				"try {",
+				"  first.getActiveTools();",
+				"} catch (error) {",
+				"  initializationError = error instanceof Error ? error.message : String(error);",
+				"}",
+				"export const runtimeContract = {",
+				"  firstFlag: first.flagValues.get('sprite'),",
+				"  secondHasFlag: second.flagValues.has('sprite'),",
+				"  initializationError,",
+				"};",
+				"export default function (pi) { void pi; }",
+			].join("\n"),
+		});
+
+		const mod = (await loadLegacyPiModule(path.join(dir, "index.ts"))) as {
+			runtimeContract: {
+				firstFlag: boolean;
+				secondHasFlag: boolean;
+				initializationError: string;
+			};
+		};
+
+		expect(mod.runtimeContract).toEqual({
+			firstFlag: true,
+			secondHasFlag: false,
+			initializationError:
+				"Extension runtime not initialized. Action methods cannot be called during extension loading.",
+		});
+	});
+
 	it("honors legacy bash operations overrides", async () => {
 		const dir = await writePackage({
 			"package.json": JSON.stringify({ name: "legacy-bash-ops-ext", version: "1.0.0" }),