fix(tui): complete slash commands after leading whitespace (#10218)

packages/tui/src/autocomplete.ts

@@ -335,11 +335,12 @@ export class CombinedAutocompleteProvider implements AutocompleteProvider {
 			};
 		}
 
-		if (!options.force && textBeforeCursor.startsWith("/")) {
-			const spaceIndex = textBeforeCursor.indexOf(" ");
+		const commandText = textBeforeCursor.trimStart();
+		if (!options.force && commandText.startsWith("/")) {
+			const spaceIndex = commandText.indexOf(" ");
 
 			if (spaceIndex === -1) {
-				const prefix = textBeforeCursor.slice(1);
+				const prefix = commandText.slice(1);
 				const commandItems = this.commands.map((cmd) => {
 					const name = "name" in cmd ? cmd.name : cmd.value;
 					const hint = "argumentHint" in cmd && cmd.argumentHint ? cmd.argumentHint : undefined;
@@ -371,12 +372,12 @@ export class CombinedAutocompleteProvider implements AutocompleteProvider {
 
 				return {
 					items: filtered,
-					prefix: textBeforeCursor,
+					prefix: commandText,
 				};
 			}
 
-			const commandName = textBeforeCursor.slice(1, spaceIndex);
-			const argumentText = textBeforeCursor.slice(spaceIndex + 1);
+			const commandName = commandText.slice(1, spaceIndex);
+			const argumentText = commandText.slice(spaceIndex + 1);
 
 			const command = this.commands.find((cmd) => {
 				const name = "name" in cmd ? cmd.name : cmd.value;

packages/tui/test/autocomplete-skill-slash.test.ts

@@ -32,6 +32,51 @@ describe("CombinedAutocompleteProvider slash-command filter", () => {
 		assert.ok(items.includes("model"));
 	});
 
+	it("completes commands after leading whitespace and preserves it", async () => {
+		const provider = new CombinedAutocompleteProvider([{ name: "model" }], process.cwd());
+		for (const [line, expected] of [
+			[" /", " /model "],
+			["  /mod", "  /model "],
+			["\t/mod", "\t/model "],
+		] as const) {
+			const result = await provider.getSuggestions([line], 0, line.length, {
+				signal: new AbortController().signal,
+			});
+			assert.ok(result);
+			assert.equal(result.prefix, line.trimStart());
+			assert.deepStrictEqual(
+				result.items.map((item) => item.value),
+				["model"],
+			);
+			const applied = provider.applyCompletion([line], 0, line.length, result.items[0]!, result.prefix);
+			assert.equal(applied.lines[0], expected);
+			assert.equal(applied.cursorCol, expected.length);
+		}
+	});
+
+	it("completes command arguments after leading whitespace", async () => {
+		const provider = new CombinedAutocompleteProvider(
+			[
+				{
+					name: "model",
+					getArgumentCompletions: (prefix: string) => {
+						assert.equal(prefix, "son");
+						return [{ value: "sonnet", label: "sonnet" }];
+					},
+				},
+			],
+			process.cwd(),
+		);
+		const line = "  /model son";
+		const result = await provider.getSuggestions([line], 0, line.length, {
+			signal: new AbortController().signal,
+		});
+		assert.ok(result);
+		assert.equal(result.prefix, "son");
+		const applied = provider.applyCompletion([line], 0, line.length, result.items[0]!, result.prefix);
+		assert.equal(applied.lines[0], "  /model sonnet");
+	});
+
 	it("keeps explicit skill: queries working", async () => {
 		const items = await suggestionsFor("skill:side");
 		assert.ok(items.includes("skill:to-sidecar"));