diff --git a/packages/coding-agent/src/changes.md b/packages/coding-agent/src/changes.md
index 0658282025..199f57a218 100644
--- a/packages/coding-agent/src/changes.md
+++ b/packages/coding-agent/src/changes.md
@@ -1,5 +1,23 @@
 # changes
 
+## Anchor compiled-binary detection to exact virtual-filesystem url shapes (2026-08-30)
+
+### What changed
+
+- `packages/coding-agent/src/config.ts`: `isBunBinary` now derives from `isCompiledBunBinaryUrl()`, which matches only the exact embedded-module url shapes (`file:///$bunfs/...`, `file:///<drive>:/~BUN/...` raw or percent-encoded) instead of unrestricted substring checks.
+
+### Why
+
+- A stock `bun run` from a disk path containing a marker segment (e.g. `/tmp/$bunfs/...`) previously classified as a compiled binary, misrouting theme/package-dir resolution and, via the new compiled-host signal, mislabeling the eval js runtime badge as `native`.
+
+### Why an extension could not handle it
+
+- `isBunBinary` is core bootstrap classification consumed by config path resolution and the bundled-extension loader.
+
+### Expected merge conflict zones
+
+- LOW: `isBunBinary` definition in `packages/coding-agent/src/config.ts`.
+
 ## Measure Cursor tool-result history at the wire representation (2026-08-29)
 
 ### What changed
diff --git a/packages/coding-agent/src/config.ts b/packages/coding-agent/src/config.ts
index 9a05aca318..1d8160de0b 100644
--- a/packages/coding-agent/src/config.ts
+++ b/packages/coding-agent/src/config.ts
@@ -17,11 +17,18 @@ const __filename = fileURLToPath(import.meta.url);
 const __dirname = dirname(__filename);
 
 /**
- * Detect if we're running as a Bun compiled binary.
- * Bun binaries have import.meta.url containing "$bunfs", "~BUN", or "%7EBUN" (Bun's virtual filesystem path)
+ * Exact module-url shape of a module embedded in a Bun compiled binary:
+ * posix `file:///$bunfs/...` or the windows virtual drive
+ * `file:///<drive>:/~BUN/...` (raw or percent-encoded). Marker-named disk
+ * paths (e.g. `file:///tmp/$bunfs/...`) never match. Shapes are mirrored by
+ * senpi-codemode's runtime-info.ts.
  */
-export const isBunBinary =
-	import.meta.url.includes("$bunfs") || import.meta.url.includes("~BUN") || import.meta.url.includes("%7EBUN");
+export function isCompiledBunBinaryUrl(moduleUrl: string): boolean {
+	return moduleUrl.startsWith("file:///$bunfs/") || /^file:\/\/\/[A-Za-z]:\/(?:~BUN|%7EBUN)\//.test(moduleUrl);
+}
+
+/** Detect if we're running as a Bun compiled binary. */
+export const isBunBinary = isCompiledBunBinaryUrl(import.meta.url);
 
 /** Detect if Bun is the runtime (compiled binary or bun run) */
 export const isBunRuntime = !!process.versions.bun;
diff --git a/packages/coding-agent/src/core/changes.md b/packages/coding-agent/src/core/changes.md
index 34dde19825..65b597f671 100644
--- a/packages/coding-agent/src/core/changes.md
+++ b/packages/coding-agent/src/core/changes.md
@@ -1,5 +1,6 @@
 # changes
 
+<<<<<<< HEAD
 ## 2026-08-30 - Experimental workflow eval-only policy
 
 ### What changed
@@ -18,6 +19,25 @@
 ### Expected merge conflict zones
 
 - `agent-session.ts`: active-tool selection, tool registry refresh, reload, and system-prompt assembly.
+
+## 2026-08-30 - Publish compiled-binary host signal for sidecar extensions
+
+### What changed
+
+- `packages/coding-agent/src/core/resource-loader.ts`: before loading a bundled extension through `resolveBinaryFactory` in a compiled binary, the loader publishes `Symbol.for("@earendil-works/pi-coding-agent:compiled-binary-host")` on `globalThis`.
+
+### Why
+
+- Compiled binaries load bundled extensions (codemode) from the physical sidecar, whose module urls carry no bunfs marker; codemode's eval runtime badge reads this host classification to label the self-hosted runtime `native`.
+
+### Why an extension could not handle it
+
+- Only the binary loader knows it is executing the compiled-host loading path; extension code loaded from the sidecar cannot observe `isBunBinary` itself.
+
+### Expected merge conflict zones
+
+- `packages/coding-agent/src/core/resource-loader.ts` (bundled builtin extension loading)
+
 ## 2026-08-29 - Bound Cursor serialized tool-result admissions
 
 ### What changed
diff --git a/packages/coding-agent/src/core/resource-loader.ts b/packages/coding-agent/src/core/resource-loader.ts
index 558960c3e0..494d927f7f 100644
--- a/packages/coding-agent/src/core/resource-loader.ts
+++ b/packages/coding-agent/src/core/resource-loader.ts
@@ -113,6 +113,14 @@ const VENDORED_BUILTIN_EXTENSION_PACKAGES: ReadonlyArray<{ builtinId: string; pa
 ];
 const moduleRequire = createRequire(import.meta.url);
 
+/**
+ * Published before loading bundled extensions from the physical sidecar of a
+ * compiled binary: sidecar module urls carry no bunfs marker, so extensions
+ * (codemode's eval runtime badge) read this host classification instead.
+ * Key convention matches the interactive theme registry.
+ */
+const COMPILED_BINARY_HOST_KEY = Symbol.for("@earendil-works/pi-coding-agent:compiled-binary-host");
+
 const bundledBuiltinExtensions: ReadonlyArray<{
 	id: string;
 	resolvePackage: () => string;
@@ -1389,6 +1397,7 @@ export class DefaultResourceLoader implements ResourceLoader {
 			}
 			try {
 				if (isBunBinary && bundledExtension.resolveBinaryFactory) {
+					Reflect.set(globalThis, COMPILED_BINARY_HOST_KEY, true);
 					const factory = await bundledExtension.resolveBinaryFactory();
 					const extensionPath = `<builtin:${bundledExtension.id}>`;
 					const extension = await loadExtensionFromFactory(
diff --git a/packages/coding-agent/test/config-compiled-binary-url.test.ts b/packages/coding-agent/test/config-compiled-binary-url.test.ts
new file mode 100644
index 0000000000..7c538ae8bf
--- /dev/null
+++ b/packages/coding-agent/test/config-compiled-binary-url.test.ts
@@ -0,0 +1,24 @@
+import { describe, expect, it } from "vitest";
+import { isCompiledBunBinaryUrl } from "../src/config.ts";
+
+describe("isCompiledBunBinaryUrl", () => {
+	it("matches the posix virtual filesystem root of a compiled binary", () => {
+		expect(isCompiledBunBinaryUrl("file:///$bunfs/root/pi")).toBe(true);
+	});
+
+	it("matches the windows virtual drive, raw and percent-encoded, any drive letter", () => {
+		expect(isCompiledBunBinaryUrl("file:///B:/~BUN/root/pi")).toBe(true);
+		expect(isCompiledBunBinaryUrl("file:///b:/%7EBUN/root/pi")).toBe(true);
+	});
+
+	it("never matches stock bun disk paths that merely contain a marker segment", () => {
+		expect(isCompiledBunBinaryUrl("file:///private/tmp/$bunfs-stock-integration/probe.ts")).toBe(false);
+		expect(isCompiledBunBinaryUrl("file:///tmp/$bunfs/project/config.ts")).toBe(false);
+		expect(isCompiledBunBinaryUrl("file:///Users/dev/~BUN/root/config.ts")).toBe(false);
+		expect(isCompiledBunBinaryUrl("file:///Users/dev/%7EBUN/root/config.ts")).toBe(false);
+	});
+
+	it("never matches ordinary disk urls", () => {
+		expect(isCompiledBunBinaryUrl("file:///Users/dev/senpi/src/config.ts")).toBe(false);
+	});
+});
diff --git a/packages/senpi-codemode/CHANGELOG.md b/packages/senpi-codemode/CHANGELOG.md
index bc3376fdb5..4578c790c2 100644
--- a/packages/senpi-codemode/CHANGELOG.md
+++ b/packages/senpi-codemode/CHANGELOG.md
@@ -8,6 +8,10 @@
 
 ### Changed
 
+- Eval header runtime badges for the js kernel now read `native` when a compiled
+  standalone binary hosts the kernel itself (an omo/pi native build), e.g.
+  `eval js (native 1.4.0, ~/.omo/…/omo)`; stock bun and node badges and the eval
+  prompt host line are unchanged.
 - The eval prompt's dependency-graph section is now `<workflow>` and states its contract directly:
   define the workflow spec in code, one node per logically distinct step, rather than hand-authoring
   the graph as a single opaque call.
diff --git a/packages/senpi-codemode/README.md b/packages/senpi-codemode/README.md
index 1c51395308..28cd51c98b 100644
--- a/packages/senpi-codemode/README.md
+++ b/packages/senpi-codemode/README.md
@@ -34,7 +34,10 @@ task-tool names are known.
   `eval js (node 26.7.0, /opt/…/bin/node)` — with the same `runtime` info on
   `EvalToolDetails` and its `cells` for RPC consumers; interpreter detection
   resolves absolute executable paths, and the eval prompt host line names the
-  JS runtime (`node`/`bun`).
+  JS runtime (`node`/`bun`). When a compiled standalone binary hosts the JS
+  kernel itself (an omo/pi native build), the badge reads `native` instead of
+  `bun` — `eval js (native 1.4.0, ~/.omo/…/omo)` — while the prompt host line
+  stays `bun` for engine capability.
 - JavaScript import rewriting for supported local modules and package imports
   in the persistent Node.js worker.
 - GPT models receive a terse `eval` prompt dialect that prioritizes composing
diff --git a/packages/senpi-codemode/src/extension/runtime-info.ts b/packages/senpi-codemode/src/extension/runtime-info.ts
index 2dd1c91985..b0001dabfa 100644
--- a/packages/senpi-codemode/src/extension/runtime-info.ts
+++ b/packages/senpi-codemode/src/extension/runtime-info.ts
@@ -6,19 +6,74 @@ export interface JsRuntimeVersions {
 	readonly bun?: string | undefined;
 }
 
-/** Identity of the in-process JS kernel host: bun when its marker exists, node otherwise. */
+/**
+ * Global-registry key the coding-agent binary loader publishes before loading
+ * this package from the physical sidecar of a compiled binary. Compiled hosts
+ * load codemode from disk, so this module's own url carries no bunfs marker;
+ * the host's classification is the authoritative signal. Follows the
+ * Symbol.for registry convention of the interactive theme.
+ */
+const COMPILED_HOST_KEY = Symbol.for("@earendil-works/pi-coding-agent:compiled-binary-host");
+
+/**
+ * Exact module-url shapes of Bun's virtual filesystem in compiled binaries:
+ * posix `file:///$bunfs/...` and the windows virtual drive
+ * `file:///<drive>:/~BUN/...` (raw or percent-encoded). Anchored so stock bun
+ * runs from disk paths that merely contain a marker segment never match.
+ */
+const POSIX_VIRTUAL_URL_PREFIX = "file:///$bunfs/";
+const WINDOWS_VIRTUAL_URL_PATTERN = /^file:\/\/\/[A-Za-z]:\/(?:~BUN|%7EBUN)\//;
+
+export interface NativeRuntimeSignals {
+	readonly bunVersion?: string | undefined;
+	readonly moduleUrl?: string | undefined;
+	readonly hostCompiledBinary?: boolean | undefined;
+}
+
+/**
+ * True when the bun runtime hosting this code is a compiled standalone binary
+ * (an omo/pi native build): the in-process JS kernel then runs inside the
+ * application binary itself rather than a stock bun install.
+ */
+export function isNativeSelfRuntime(signals: NativeRuntimeSignals = processNativeSignals()): boolean {
+	const bun = signals.bunVersion;
+	if (bun === undefined || bun.length === 0) return false;
+	if (signals.hostCompiledBinary === true) return true;
+	const moduleUrl = signals.moduleUrl ?? "";
+	return moduleUrl.startsWith(POSIX_VIRTUAL_URL_PREFIX) || WINDOWS_VIRTUAL_URL_PATTERN.test(moduleUrl);
+}
+
+function processNativeSignals(): NativeRuntimeSignals {
+	return {
+		bunVersion: process.versions.bun,
+		moduleUrl: import.meta.url,
+		hostCompiledBinary: Reflect.get(globalThis, COMPILED_HOST_KEY) === true,
+	};
+}
+
+/**
+ * Identity of the in-process JS kernel host: native when a compiled binary
+ * hosts the kernel itself, bun when its marker exists, node otherwise.
+ */
 export function jsRuntimeInfo(
 	versions: JsRuntimeVersions = process.versions,
 	execPath: string = process.execPath,
+	nativeSelf: boolean = isNativeSelfRuntime(),
 ): EvalRuntimeInfo {
 	const bun = versions.bun;
-	if (bun !== undefined && bun.length > 0) return { name: "bun", version: bun, path: execPath };
+	if (bun !== undefined && bun.length > 0) {
+		return { name: nativeSelf ? "native" : "bun", version: bun, path: execPath };
+	}
 	return { name: "node", version: versions.node, path: execPath };
 }
 
-/** Short host-line segment, e.g. "node 26.7.0" or "bun 1.4.0". */
+/**
+ * Short host-line segment, e.g. "node 26.7.0" or "bun 1.4.0". Stays
+ * runtime-truthful for the eval prompt, so a native binary still reads "bun":
+ * the model needs the engine capability surface, not the install identity.
+ */
 export function jsRuntimeLabel(versions: JsRuntimeVersions = process.versions): string {
-	const info = jsRuntimeInfo(versions, "");
+	const info = jsRuntimeInfo(versions, "", false);
 	return `${info.name} ${info.version}`;
 }
 
diff --git a/packages/senpi-codemode/test/eval-render-runtime.test.ts b/packages/senpi-codemode/test/eval-render-runtime.test.ts
index bf68f91796..8c64fe153e 100644
--- a/packages/senpi-codemode/test/eval-render-runtime.test.ts
+++ b/packages/senpi-codemode/test/eval-render-runtime.test.ts
@@ -58,6 +58,27 @@ describe("eval renderer runtime badge", () => {
 		expect(rendered[0]).toBe("eval js (node 26.7.0) done");
 	});
 
+	it("labels the js runtime as native when the kernel runs inside the compiled binary", () => {
+		const details: EvalToolDetails = {
+			language: "js",
+			durationMs: 0,
+			toolCalls: [],
+			truncated: false,
+			runtime: { name: "native", version: "1.4.0" },
+		};
+
+		const rendered = renderLines(
+			renderEvalResult(
+				evalResult(details, "complete"),
+				{ expanded: false, isPartial: false },
+				undefined,
+				resultContext(undefined, false),
+			),
+		);
+
+		expect(rendered[0]).toBe("eval js (native 1.4.0) done");
+	});
+
 	it("renders headers without any badge when runtime is unknown", () => {
 		const rendered = renderLines(
 			renderEvalResult(
diff --git a/packages/senpi-codemode/test/runtime-info.test.ts b/packages/senpi-codemode/test/runtime-info.test.ts
index 5fe074ffd8..92a86f891c 100644
--- a/packages/senpi-codemode/test/runtime-info.test.ts
+++ b/packages/senpi-codemode/test/runtime-info.test.ts
@@ -1,5 +1,10 @@
 import { describe, expect, it } from "vitest";
-import { jsRuntimeInfo, jsRuntimeLabel, runtimesFromAvailability } from "../src/extension/runtime-info.ts";
+import {
+	isNativeSelfRuntime,
+	jsRuntimeInfo,
+	jsRuntimeLabel,
+	runtimesFromAvailability,
+} from "../src/extension/runtime-info.ts";
 import type { InterpreterAvailability, LanguageAvailability } from "../src/interpreters/detect.ts";
 
 const unavailable: LanguageAvailability = { enabled: false, detected: { ok: false } };
@@ -30,6 +35,85 @@ describe("jsRuntimeInfo", () => {
 			path: "/usr/local/bin/node",
 		});
 	});
+
+	it("reports native when the bun runtime is the compiled binary itself", () => {
+		expect(jsRuntimeInfo({ node: "26.7.0", bun: "1.4.0" }, "/Users/dev/.omo/binary-runtime/omo", true)).toEqual({
+			name: "native",
+			version: "1.4.0",
+			path: "/Users/dev/.omo/binary-runtime/omo",
+		});
+	});
+
+	it("keeps the bun name when the runtime is a stock bun install", () => {
+		expect(jsRuntimeInfo({ node: "26.7.0", bun: "1.4.0" }, "/opt/bun/bin/bun", false)).toEqual({
+			name: "bun",
+			version: "1.4.0",
+			path: "/opt/bun/bin/bun",
+		});
+	});
+
+	it("never reports native without the bun marker", () => {
+		expect(jsRuntimeInfo({ node: "26.7.0" }, "/usr/local/bin/node", true)).toEqual({
+			name: "node",
+			version: "26.7.0",
+			path: "/usr/local/bin/node",
+		});
+	});
+});
+
+describe("isNativeSelfRuntime", () => {
+	it("trusts the compiled-host signal even when the module loads from a disk sidecar", () => {
+		expect(
+			isNativeSelfRuntime({
+				bunVersion: "1.4.0",
+				hostCompiledBinary: true,
+				moduleUrl: "file:///Users/dev/node_modules/@code-yeongyu/senpi-codemode/src/extension/runtime-info.ts",
+			}),
+		).toBe(true);
+	});
+
+	it("ignores the compiled-host signal without the bun marker", () => {
+		expect(
+			isNativeSelfRuntime({ bunVersion: undefined, hostCompiledBinary: true, moduleUrl: "file:///x/y.ts" }),
+		).toBe(false);
+	});
+
+	it("detects the bun virtual filesystem in the module url of a compiled binary", () => {
+		expect(isNativeSelfRuntime({ bunVersion: "1.4.0", moduleUrl: "file:///$bunfs/root/runtime-info.ts" })).toBe(true);
+	});
+
+	it("detects windows virtual filesystem markers, raw and url-encoded", () => {
+		expect(isNativeSelfRuntime({ bunVersion: "1.4.0", moduleUrl: "file:///B:/~BUN/root/runtime-info.ts" })).toBe(
+			true,
+		);
+		expect(isNativeSelfRuntime({ bunVersion: "1.4.0", moduleUrl: "file:///B:/%7EBUN/root/runtime-info.ts" })).toBe(
+			true,
+		);
+	});
+
+	it("stays false for stock bun runs loading modules from disk", () => {
+		expect(isNativeSelfRuntime({ bunVersion: "1.4.0", moduleUrl: "file:///Users/dev/src/runtime-info.ts" })).toBe(
+			false,
+		);
+	});
+
+	it("stays false when a stock bun disk path merely contains a marker segment", () => {
+		expect(
+			isNativeSelfRuntime({ bunVersion: "1.4.0", moduleUrl: "file:///tmp/$bunfs/project/runtime-info.ts" }),
+		).toBe(false);
+		expect(
+			isNativeSelfRuntime({ bunVersion: "1.4.0", moduleUrl: "file:///Users/dev/~BUN/root/runtime-info.ts" }),
+		).toBe(false);
+		expect(
+			isNativeSelfRuntime({ bunVersion: "1.4.0", moduleUrl: "file:///Users/dev/%7EBUN/root/runtime-info.ts" }),
+		).toBe(false);
+	});
+
+	it("stays false under node even when the module url carries a marker", () => {
+		expect(isNativeSelfRuntime({ bunVersion: undefined, moduleUrl: "file:///$bunfs/root/runtime-info.ts" })).toBe(
+			false,
+		);
+	});
 });
 
 describe("jsRuntimeLabel", () => {
diff --git a/packages/senpi-codemode/test/runtime-label.test.ts b/packages/senpi-codemode/test/runtime-label.test.ts
index abfe5719fc..17769f1504 100644
--- a/packages/senpi-codemode/test/runtime-label.test.ts
+++ b/packages/senpi-codemode/test/runtime-label.test.ts
@@ -18,6 +18,12 @@ describe("formatRuntimeBadge", () => {
 		).toBe("bun 1.4.0, /usr/local/bin/bun");
 	});
 
+	it("labels the native self-hosted runtime like any js runtime", () => {
+		expect(
+			formatRuntimeBadge("js", { name: "native", version: "1.4.0", path: "/Users/dev/.omo/bin/omo" }, "/Users/dev"),
+		).toBe("native 1.4.0, ~/.omo/bin/omo");
+	});
+
 	it("falls back to a version-only badge when no path is known", () => {
 		expect(formatRuntimeBadge("py", { name: "python", version: "3.12.4" }, "/Users/dev")).toBe("3.12.4");
 	});