fix(discovery): load Claude plugin skill paths that point at a SKILL.md directory

Claude plugin manifests may declare a `skills` path that resolves directly to a
directory whose `SKILL.md` IS the skill (e.g. `"skills": ["./"]` or a
subdirectory containing only `SKILL.md`). `scanSkillsFromDir` only scanned
`<dir>/<name>/SKILL.md` children, so the single-skill directory layout — the
common shape the Claude plugins reference documents for plugins shipping one
skill — silently dropped every array-form manifest entry that pointed at it.

Add an opt-in `includeSelf` flag to `ScanSkillsFromDirOptions`: when set,
`<dir>/SKILL.md` (if present) is loaded as a skill in addition to the existing
child scan. The Claude plugin skills loader opts in; every other provider
(agents, builtin, claude.ts, codex, github, omp-plugins, opencode) keeps the
strict child-scan semantic they rely on. Frontmatter `name` still wins over
the directory basename fallback.

Regression test: `skills: ["./single"]` where `./single/SKILL.md` is the only
skill file loads the skill under its frontmatter name.

packages/coding-agent/src/discovery/claude-plugins.ts

@@ -169,6 +169,7 @@ async function loadSkills(ctx: LoadContext): Promise<LoadResult<Skill>> {
 						dir,
 						providerId: PROVIDER_ID,
 						level: root.scope,
+						includeSelf: true,
 					}),
 				),
 			);

packages/coding-agent/src/discovery/helpers.ts

@@ -312,6 +312,15 @@ export interface ScanSkillsFromDirOptions {
 	providerId: string;
 	level: "user" | "project";
 	requireDescription?: boolean;
+	/**
+	 * When true, treat a `SKILL.md` sitting directly under `dir` as a single skill in addition to
+	 * scanning `<dir>/<name>/SKILL.md` children. Matches the Claude plugin manifest convention
+	 * that lets a skill path point at a directory containing `SKILL.md` directly (e.g.
+	 * `"skills": ["./"]`), where the frontmatter `name` determines the invocation name and the
+	 * directory basename is the fallback. Default `false` preserves the strict child-scan
+	 * semantic every non-Claude provider relies on.
+	 */
+	includeSelf?: boolean;
 }
 
 // Stable ordering used for skill lists in prompts: name (case-insensitive), then name, then path.
@@ -368,7 +377,13 @@ export async function scanSkillsFromDir(
 		}
 	};
 
-	const work = [];
+	const work: Promise<void>[] = [];
+	if (options.includeSelf) {
+		const selfSkillPath = path.join(dir, "SKILL.md");
+		if (fs.existsSync(selfSkillPath)) {
+			work.push(loadSkill(selfSkillPath));
+		}
+	}
 	for (const entry of entries) {
 		if (entry.name.startsWith(".")) continue;
 		if (!entry.isDirectory() && !entry.isSymbolicLink()) continue;

packages/coding-agent/test/discovery/claude-plugins.test.ts

@@ -859,6 +859,45 @@ describe("listClaudePluginRoots", () => {
 		expect(result.all.find(s => s.name === "extra-skill")).toBeDefined();
 	});
 
+	test("array-form skills entry pointing at a directory containing SKILL.md loads the single skill", async () => {
+		// Per Claude plugins reference: a skills path may point directly at a directory whose
+		// SKILL.md is the skill (frontmatter name → invocation, directory basename → fallback).
+		// Real plugins use `"skills": ["./"]` — that entry must not silently drop the skill.
+		const pluginsDir = path.join(tempDir, ".claude", "plugins");
+		const pluginPath = path.join(tempDir, "plugins", "manifest-skills-self");
+		await fs.mkdir(pluginsDir, { recursive: true });
+		await fs.mkdir(path.join(pluginPath, ".claude-plugin"), { recursive: true });
+		await fs.mkdir(path.join(pluginPath, "single"), { recursive: true });
+
+		const registry = {
+			version: 2,
+			plugins: {
+				"manifest-skills-self@market": [
+					{
+						scope: "user",
+						installPath: pluginPath,
+						version: "1.0.0",
+						installedAt: "2025-01-01T00:00:00Z",
+						lastUpdated: "2025-01-01T00:00:00Z",
+					},
+				],
+			},
+		};
+		await fs.writeFile(path.join(pluginsDir, "installed_plugins.json"), JSON.stringify(registry));
+		await fs.writeFile(
+			path.join(pluginPath, ".claude-plugin", "plugin.json"),
+			JSON.stringify({ skills: ["./single"] }),
+		);
+		await fs.writeFile(
+			path.join(pluginPath, "single", "SKILL.md"),
+			"---\nname: solo-skill\ndescription: Solo skill\n---\nBody\n",
+		);
+
+		const result = await loadCapability<Skill>("skills", { cwd: tempDir });
+		expect(result.warnings).toEqual([]);
+		expect(result.all.find(s => s.name === "solo-skill")).toBeDefined();
+	});
+
 	test("manifest commands field replaces default commands/ directory (Claude replace semantics)", async () => {
 		// Per Claude plugins reference "Path behavior rules":
 		// `commands` REPLACES the default `commands/` scan when the manifest key is set.