diff --git a/packages/pi-coding-agent/src/modes/interactive/controllers/input-controller.test.ts b/packages/pi-coding-agent/src/modes/interactive/controllers/input-controller.test.ts
index 33f67c42a..6f5d22da5 100644
--- a/packages/pi-coding-agent/src/modes/interactive/controllers/input-controller.test.ts
+++ b/packages/pi-coding-agent/src/modes/interactive/controllers/input-controller.test.ts
@@ -154,3 +154,30 @@ test("input-controller: truly unknown slash commands stop before session.prompt"
 	);
 	assert.equal(getEditorText(), "", "unknown slash commands should clear the editor after showing the error");
 });
+
+test("input-controller: absolute file paths are not treated as slash commands (#3478)", async () => {
+	const { host, prompted, errors } = createHost();
+
+	await host.defaultEditor.onSubmit("/Users/name/Desktop/screenshot.png");
+
+	assert.deepEqual(errors, [], "file paths should not trigger unknown command error");
+	assert.deepEqual(prompted, ["/Users/name/Desktop/screenshot.png"], "file paths should be sent as plain input");
+});
+
+test("input-controller: Linux absolute paths are not treated as slash commands (#3478)", async () => {
+	const { host, prompted, errors } = createHost();
+
+	await host.defaultEditor.onSubmit("/home/user/documents/file.txt");
+
+	assert.deepEqual(errors, [], "Linux paths should not trigger unknown command error");
+	assert.deepEqual(prompted, ["/home/user/documents/file.txt"], "Linux paths should be sent as plain input");
+});
+
+test("input-controller: /tmp paths are not treated as slash commands (#3478)", async () => {
+	const { host, prompted, errors } = createHost();
+
+	await host.defaultEditor.onSubmit("/tmp/some-file.log");
+
+	assert.deepEqual(errors, []);
+	assert.deepEqual(prompted, ["/tmp/some-file.log"]);
+});
diff --git a/packages/pi-coding-agent/src/modes/interactive/controllers/input-controller.ts b/packages/pi-coding-agent/src/modes/interactive/controllers/input-controller.ts
index 3c7c1537d..a1fefba87 100644
--- a/packages/pi-coding-agent/src/modes/interactive/controllers/input-controller.ts
+++ b/packages/pi-coding-agent/src/modes/interactive/controllers/input-controller.ts
@@ -18,7 +18,7 @@ export function setupEditorSubmitHandler(host: InteractiveModeStateHost & {
 		text = text.trim();
 		if (!text) return;
 
-		if (text.startsWith("/")) {
+		if (text.startsWith("/") && !looksLikeFilePath(text)) {
 			const handled = await dispatchSlashCommand(text, host.getSlashCommandContext());
 			if (handled) {
 				host.editor.setText("");
@@ -104,3 +104,18 @@ export function setupEditorSubmitHandler(host: InteractiveModeStateHost & {
 		}
 	};
 }
+
+/**
+ * Distinguish absolute file paths from slash commands (#3478).
+ * Drag-and-drop inserts paths like "/Users/name/Desktop/file.png" which
+ * should be treated as plain text input, not a /Users command.
+ *
+ * Heuristic: a slash command is a single token like "/help" or "/gsd auto".
+ * File paths have a second "/" within the first token (e.g., "/Users/...").
+ */
+function looksLikeFilePath(text: string): boolean {
+	const firstToken = text.split(/\s/)[0];
+	// Slash commands: /help, /gsd, /commit — single "/" at start only.
+	// File paths: /Users/name/file, /home/user/file, /tmp/x — contain "/" after position 0.
+	return firstToken.indexOf("/", 1) !== -1;
+}