feat(lsp): add directory support to lsp_diagnostics via extension param

- Add isDirectoryPath helper to lsp-client-wrapper.ts
- Create directory-diagnostics.ts with aggregateDiagnosticsForDirectory
- Update diagnostics-tool.ts with extension parameter for directory paths
- Update Atlas agent prompts to use extension param for directory diagnostics
- Add unit tests for isDirectoryPath and aggregateDiagnosticsForDirectory

Fixes #2362

src/tools/lsp/directory-diagnostics.test.ts

@@ -0,0 +1,56 @@
+import { describe, expect, it } from "bun:test"
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from "fs"
+import { join } from "path"
+import os from "os"
+
+import { isDirectoryPath } from "./lsp-client-wrapper"
+import { aggregateDiagnosticsForDirectory } from "./directory-diagnostics"
+
+describe("directory diagnostics", () => {
+  describe("isDirectoryPath", () => {
+    it("returns true for existing directory", () => {
+      const tmp = mkdtempSync(join(os.tmpdir(), "omo-isdir-"))
+      try {
+        expect(isDirectoryPath(tmp)).toBe(true)
+      } finally {
+        rmSync(tmp, { recursive: true, force: true })
+      }
+    })
+
+    it("returns false for existing file", () => {
+      const tmp = mkdtempSync(join(os.tmpdir(), "omo-isdir-file-"))
+      try {
+        const file = join(tmp, "test.txt")
+        writeFileSync(file, "content")
+        expect(isDirectoryPath(file)).toBe(false)
+      } finally {
+        rmSync(tmp, { recursive: true, force: true })
+      }
+    })
+
+    it("returns false for non-existent path", () => {
+      const nonExistent = join(os.tmpdir(), "omo-nonexistent-" + Date.now())
+      expect(isDirectoryPath(nonExistent)).toBe(false)
+    })
+  })
+
+  describe("aggregateDiagnosticsForDirectory", () => {
+    it("throws error when extension does not start with dot", async () => {
+      const tmp = mkdtempSync(join(os.tmpdir(), "omo-aggr-ext-"))
+      try {
+        await expect(aggregateDiagnosticsForDirectory(tmp, "ts")).rejects.toThrow(
+          'Extension must start with a dot (e.g., ".ts", not "ts")'
+        )
+      } finally {
+        rmSync(tmp, { recursive: true, force: true })
+      }
+    })
+
+    it("throws error when directory does not exist", async () => {
+      const nonExistent = join(os.tmpdir(), "omo-nonexistent-dir-" + Date.now())
+      await expect(aggregateDiagnosticsForDirectory(nonExistent, ".ts")).rejects.toThrow(
+        "Directory does not exist"
+      )
+    })
+  })
+})