1 files changed, 154 insertions, 47 deletions
diff --git a/packages/lsp/src/diagnostics.test.ts b/packages/lsp/src/diagnostics.test.ts
index 9f2b6b4..70b1ffa 100644
--- a/packages/lsp/src/diagnostics.test.ts
+++ b/packages/lsp/src/diagnostics.test.ts
@@ -1,51 +1,158 @@
 import { describe, expect, it } from "vitest";
-import { DiagnosticsStore } from "./diagnostics.js";
+import { type Diagnostic, DiagnosticsStore } from "./diagnostics.js";
 
 describe("diagnostics", () => {
-	it("formats diagnostics with severity, location, and message", () => {
-		const store = new DiagnosticsStore();
-		store.setPushDiagnostics({
-			uri: "file:///test.ts",
-			diagnostics: [
-				{
-					range: { start: { line: 0, character: 5 }, end: { line: 0, character: 10 } },
-					severity: 1,
-					source: "typescript",
-					message: "Cannot find name 'hello'.",
-				},
-			],
-		});
-
-		const formatted = store.format("file:///test.ts");
-		expect(formatted).toContain("ERROR");
-		expect(formatted).toContain("L1:6");
-		expect(formatted).toContain("Cannot find name 'hello'.");
-		expect(formatted).toContain("[typescript]");
-	});
-
-	it("merges push and pull diagnostics with deduplication", () => {
-		const store = new DiagnosticsStore();
-		const diag = {
-			range: { start: { line: 0, character: 0 }, end: { line: 0, character: 5 } },
-			severity: 1,
-			message: "Error",
-		};
-
-		store.setPushDiagnostics({
-			uri: "file:///test.ts",
-			diagnostics: [diag],
-		});
-		store.setPullDiagnostics("file:///test.ts", {
-			kind: "full",
-			items: [diag],
-		});
-
-		const merged = store.getMerged("file:///test.ts");
-		expect(merged).toHaveLength(1);
-	});
-
-	it("returns empty string when no diagnostics exist", () => {
-		const store = new DiagnosticsStore();
-		expect(store.format("file:///nonexistent.ts")).toBe("");
-	});
+  it("formats diagnostics with severity, location, and message", () => {
+    const store = new DiagnosticsStore();
+    store.setPushDiagnostics({
+      uri: "file:///test.ts",
+      diagnostics: [
+        {
+          range: { start: { line: 0, character: 5 }, end: { line: 0, character: 10 } },
+          severity: 1,
+          source: "typescript",
+          message: "Cannot find name 'hello'.",
+        },
+      ],
+    });
+
+    const formatted = store.format("file:///test.ts");
+    expect(formatted).toContain("ERROR");
+    expect(formatted).toContain("L1:6");
+    expect(formatted).toContain("Cannot find name 'hello'.");
+    expect(formatted).toContain("[typescript]");
+  });
+
+  it("merges push and pull diagnostics with deduplication", () => {
+    const store = new DiagnosticsStore();
+    const diag = {
+      range: { start: { line: 0, character: 0 }, end: { line: 0, character: 5 } },
+      severity: 1,
+      message: "Error",
+    };
+
+    store.setPushDiagnostics({
+      uri: "file:///test.ts",
+      diagnostics: [diag],
+    });
+    store.setPullDiagnostics("file:///test.ts", {
+      kind: "full",
+      items: [diag],
+    });
+
+    const merged = store.getMerged("file:///test.ts");
+    expect(merged).toHaveLength(1);
+  });
+
+  it("returns empty string when no diagnostics exist", () => {
+    const store = new DiagnosticsStore();
+    expect(store.format("file:///nonexistent.ts")).toBe("");
+  });
+
+  it("purge drops push diagnostics, pull diagnostics, and the received flag (Bug 3)", () => {
+    const store = new DiagnosticsStore();
+    store.setPushDiagnostics({
+      uri: "file:///project/a.ts",
+      diagnostics: [
+        {
+          range: { start: { line: 0, character: 0 }, end: { line: 0, character: 1 } },
+          severity: 1,
+          message: "boom",
+        },
+      ],
+    });
+    store.setPullDiagnostics("file:///project/a.ts", {
+      kind: "full",
+      items: [
+        {
+          range: { start: { line: 1, character: 0 }, end: { line: 1, character: 1 } },
+          severity: 2,
+          message: "warn",
+        },
+      ],
+    });
+    expect(store.hasReceivedPush("file:///project/a.ts")).toBe(true);
+    expect(store.format("file:///project/a.ts")).toContain("boom");
+
+    store.purge("file:///project/a.ts");
+
+    // Everything for that URI is gone — the store no longer retains it.
+    expect(store.hasReceivedPush("file:///project/a.ts")).toBe(false);
+    expect(store.format("file:///project/a.ts")).toBe("");
+    expect(store.getMerged("file:///project/a.ts")).toHaveLength(0);
+
+    // Other URIs are untouched.
+    expect(store.format("file:///project/b.ts")).toBe("");
+  });
+
+  it("bounds pushDiagnostics — oldest background file is evicted past the cap (Bug 3 remainder)", () => {
+    // Language servers scan the workspace and push diagnostics for files the
+    // agent never opened. These never enter the client's openDocuments LRU,
+    // so without an independent cap the pushDiagnostics map grows forever.
+    const store = new DiagnosticsStore();
+    const CAP = 100;
+
+    const diag = (uri: string): readonly Diagnostic[] => [
+      {
+        range: { start: { line: 0, character: 0 }, end: { line: 0, character: 1 } },
+        severity: 1,
+        message: `err in ${uri}`,
+      },
+    ];
+
+    // Push `CAP` distinct background files (at the cap — none evicted yet).
+    for (let i = 0; i < CAP; i++) {
+      store.setPushDiagnostics({ uri: `file:///bg/file${i}.ts`, diagnostics: diag(`file${i}`) });
+    }
+    expect(store.hasReceivedPush("file:///bg/file0.ts")).toBe(true);
+    expect(store.format("file:///bg/file0.ts")).toContain("err in file0");
+
+    // One past the cap → the least-recently-pushed (file0) is evicted.
+    store.setPushDiagnostics({
+      uri: "file:///bg/file100.ts",
+      diagnostics: diag("file100"),
+    });
+
+    // file0 (oldest) is gone — no didClose, no retained diagnostics, no flag.
+    expect(store.hasReceivedPush("file:///bg/file0.ts")).toBe(false);
+    expect(store.format("file:///bg/file0.ts")).toBe("");
+    expect(store.getMerged("file:///bg/file0.ts")).toHaveLength(0);
+
+    // The newest (file100) and a middle entry are retained.
+    expect(store.hasReceivedPush("file:///bg/file100.ts")).toBe(true);
+    expect(store.format("file:///bg/file100.ts")).toContain("err in file100");
+    expect(store.format("file:///bg/file50.ts")).toContain("err in file50");
+  });
+
+  it("re-pushing a URI refreshes its LRU position so it is not evicted", () => {
+    const store = new DiagnosticsStore();
+    const CAP = 100;
+
+    const diag = (uri: string): readonly Diagnostic[] => [
+      {
+        range: { start: { line: 0, character: 0 }, end: { line: 0, character: 1 } },
+        severity: 1,
+        message: uri,
+      },
+    ];
+
+    for (let i = 0; i < CAP; i++) {
+      store.setPushDiagnostics({ uri: `file:///bg/file${i}.ts`, diagnostics: diag(`file${i}`) });
+    }
+
+    // Re-push file0 (an actively-edited file gets re-pushed on each change):
+    // this should move it to the tail (most-recently-used), NOT leave it at
+    // the head where it would be the first eviction candidate.
+    store.setPushDiagnostics({ uri: "file:///bg/file0.ts", diagnostics: diag("file0-updated") });
+
+    // Now push one past the cap. file1 (now the oldest untouched) should be
+    // evicted; file0 (refreshed) must survive.
+    store.setPushDiagnostics({ uri: "file:///bg/file100.ts", diagnostics: diag("file100") });
+
+    expect(store.hasReceivedPush("file:///bg/file0.ts")).toBe(true);
+    expect(store.format("file:///bg/file0.ts")).toContain("file0-updated");
+
+    expect(store.hasReceivedPush("file:///bg/file1.ts")).toBe(false);
+    expect(store.format("file:///bg/file1.ts")).toBe("");
+  });
 });