Read skills from the global and workspace .agents/skills directories

- Discover skill directories under ~/.agents/skills and each
  workspace''s .agents/skills; a directory qualifies with a full
  skill.manifest.json or just a SKILL.md, whose manifest is derived
  (frontmatter name or the directory name). Paths resolve per platform
  on Windows, macOS, and Linux.
- Sync at startup for every organization and again when the Skills
  page opens; skills the org already carries are skipped, and one
  broken directory cannot block the rest.
- AGENTCOMPANY_NEW_SKILLS_ROOT points tests at a temporary library
  (overriding USERPROFILE crashes Electron on Windows).

tests/unit/skill-discovery.test.ts

@@ -0,0 +1,108 @@
+import { randomUUID } from "node:crypto";
+import { mkdirSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { describe, expect, test } from "vitest";
+import { DatabaseConnection } from "../../src/main/database/connection";
+import { OrganizationService } from "../../src/main/services/organization-service";
+import { SkillService } from "../../src/main/services/skill-service";
+import { syncSkillsFromDisk } from "../../src/main/services/skill-discovery";
+
+interface Harness {
+  connection: DatabaseConnection;
+  skills: SkillService;
+  orgId: string;
+  globalRoot: string;
+  workspaceRoot: string;
+}
+
+function harness(): Harness {
+  const connection = new DatabaseConnection(join(tmpdir(), `ac-skdisc-${randomUUID()}.db`));
+  const organization = new OrganizationService(connection.db);
+  const workspaceRoot = join(tmpdir(), `ac-skdisc-ws-${randomUUID()}`);
+  mkdirSync(workspaceRoot, { recursive: true });
+  let orgId = "";
+  connection.transaction(() => {
+    orgId = organization.createOrganization({ organizationName: "OrbitOps", employeeName: "Yang", mission: "m", goal: "g" });
+    organization.createWorkspace({ orgId, name: "HQ", localPath: workspaceRoot, projectId: null });
+  });
+  const globalRoot = join(tmpdir(), `ac-skdisc-global-${randomUUID()}`);
+  mkdirSync(globalRoot, { recursive: true });
+  const artifactRoot = join(tmpdir(), `ac-skdisc-art-${randomUUID()}`);
+  return { connection, skills: new SkillService(connection.db, artifactRoot), orgId, globalRoot, workspaceRoot };
+}
+
+function writeManifestSkill(root: string, dirName: string, name: string): void {
+  const dir = join(root, dirName);
+  mkdirSync(join(dir, "checks"), { recursive: true });
+  writeFileSync(join(dir, "SKILL.md"), `Guide for ${name}.\n`, "utf8");
+  writeFileSync(join(dir, "checks", "acceptance.txt"), "accepted\n", "utf8");
+  writeFileSync(join(dir, "skill.manifest.json"), JSON.stringify({
+    name,
+    version: "1.0.0",
+    entrypoint: "SKILL.md",
+    capabilities: ["review"],
+    required_tools: ["git"],
+    compatible_models: ["gpt-5.4"],
+    risk_level: "low",
+    tests: ["checks/acceptance.txt"],
+    inputs: {},
+    outputs: {},
+  }, null, 2), "utf8");
+}
+
+function writeMarkdownOnlySkill(root: string, dirName: string, frontmatterName: string | null): void {
+  const dir = join(root, dirName);
+  mkdirSync(dir, { recursive: true });
+  const frontmatter = frontmatterName ? `---\nname: ${frontmatterName}\ndescription: does things\n---\n\n` : "";
+  writeFileSync(join(dir, "SKILL.md"), `${frontmatter}# Steps\nDo the thing.\n`, "utf8");
+}
+
+function skillNames(h: Harness): string[] {
+  return (h.connection.db.prepare("select name from skill_definitions where org_id = ? order by name asc").all(h.orgId) as Array<{ name: string }>)
+    .map((row) => row.name);
+}
+
+describe("skill discovery", () => {
+  test("imports skills from the global directory and every workspace", () => {
+    const h = harness();
+    writeManifestSkill(h.globalRoot, "release-gate", "Release Gate");
+    writeMarkdownOnlySkill(join(h.workspaceRoot, ".agents", "skills"), "code-style", "Code Style");
+
+    const report = syncSkillsFromDisk(h.connection.db, h.skills, h.orgId, h.globalRoot);
+    expect(report.imported).toBe(2);
+    expect(report.failures).toEqual([]);
+    expect(skillNames(h)).toEqual(["Code Style", "Release Gate"]);
+  });
+
+  test("a SKILL.md without frontmatter falls back to the directory name", () => {
+    const h = harness();
+    writeMarkdownOnlySkill(h.globalRoot, "incident-runbook", null);
+    syncSkillsFromDisk(h.connection.db, h.skills, h.orgId, h.globalRoot);
+    expect(skillNames(h)).toEqual(["incident-runbook"]);
+  });
+
+  test("re-syncing skips what the org already carries", () => {
+    const h = harness();
+    writeManifestSkill(h.globalRoot, "release-gate", "Release Gate");
+    syncSkillsFromDisk(h.connection.db, h.skills, h.orgId, h.globalRoot);
+    const second = syncSkillsFromDisk(h.connection.db, h.skills, h.orgId, h.globalRoot);
+    expect(second.imported).toBe(0);
+    expect(second.skipped).toBe(1);
+    expect(skillNames(h)).toEqual(["Release Gate"]);
+  });
+
+  test("one broken directory cannot block the rest", () => {
+    const h = harness();
+    writeManifestSkill(h.globalRoot, "good", "Good Skill");
+    const broken = join(h.globalRoot, "broken");
+    mkdirSync(broken, { recursive: true });
+    writeFileSync(join(broken, "skill.manifest.json"), "{ not json", "utf8");
+    writeFileSync(join(broken, "SKILL.md"), "x", "utf8");
+
+    const report = syncSkillsFromDisk(h.connection.db, h.skills, h.orgId, h.globalRoot);
+    expect(report.imported).toBe(1);
+    expect(report.failures).toHaveLength(1);
+    expect(skillNames(h)).toEqual(["Good Skill"]);
+  });
+});