fix: query diagnostics only for visible documents

CHANGELOG.md

@@ -5,6 +5,12 @@ Format based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ---
 
+## [Unreleased]
+
+### Fixed
+
+- Query diagnostics only for visible documents and count split editors once per document, avoiding a workspace-wide scan on every diagnostics event.
+
 ## [2.0.0] - 2026-09-25
 
 *The massive Companion Update! Bringing new pet species, a persistent sidebar view, wearables, and interactivity to CodeCritter.*

extension.js

@@ -323,14 +323,18 @@ function activate(context) {
 
   // ── Event: Diagnostics (errors/warnings) ──
   const onDiagnostics = vscode.languages.onDidChangeDiagnostics(() => {
-    // Only scan diagnostics from open editors to avoid noisy workspace-wide counts
-    const openUris = vscode.window.visibleTextEditors.map(e => e.document.uri.toString());
-    const allDiags = vscode.languages.getDiagnostics();
-    const errorCount = allDiags
-      .filter(([uri]) => openUris.includes(uri.toString()))
-      .flatMap(([, diags]) => diags)
-      .filter(d => d.severity === vscode.DiagnosticSeverity.Error)
-      .length;
+    // Query each visible document once, even when it is open in split editors.
+    const seen = new Set();
+    let errorCount = 0;
+    for (const editor of vscode.window.visibleTextEditors) {
+      const uri = editor.document.uri;
+      const key = uri.toString();
+      if (seen.has(key)) continue;
+      seen.add(key);
+      for (const diagnostic of vscode.languages.getDiagnostics(uri)) {
+        if (diagnostic.severity === vscode.DiagnosticSeverity.Error) errorCount++;
+      }
+    }
 
     // Award credit for errors fixed
     if (errorCount < prevErrorCount) {

tests/diagnostics.test.js

@@ -0,0 +1,82 @@
+'use strict';
+
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const test = require('node:test');
+const vm = require('node:vm');
+
+test('diagnostics queries only distinct visible documents and credits fixed errors', () => {
+  const disposable = { dispose() {} };
+  const calls = [];
+  let onDiagnostics;
+  let fixed = 0;
+  const uri = { toString: () => 'file:///visible.js' };
+  let diagnostics = [{ severity: 0 }, { severity: 1 }];
+  const statusBar = { show() {}, hide() {} };
+  const vscode = {
+    DiagnosticSeverity: { Error: 0 },
+    StatusBarAlignment: { Right: 1 },
+    MarkdownString: class { constructor(value) { this.value = value; } },
+    commands: { registerCommand: () => disposable },
+    workspace: {
+      getConfiguration: () => ({ get: (key, fallback) => key === 'weeklyReview' ? false : fallback }),
+      onDidSaveTextDocument: () => disposable,
+      onDidChangeTextDocument: () => disposable,
+      onDidChangeConfiguration: () => disposable
+    },
+    window: {
+      createStatusBarItem: () => statusBar,
+      registerWebviewViewProvider: () => disposable,
+      visibleTextEditors: [{ document: { uri } }, { document: { uri } }]
+    },
+    languages: {
+      onDidChangeDiagnostics: callback => { onDiagnostics = callback; return disposable; },
+      getDiagnostics: requested => {
+        assert.equal(requested, uri, 'must never scan the workspace');
+        calls.push(requested);
+        return diagnostics;
+      }
+    }
+  };
+  const dependencies = {
+    vscode,
+    './src/stats': { StatsEngine: class {
+      getLevel() { return 1; }
+      getSnapshot() { return { level: 1, saveCount: 0, linesTyped: 0, currentStreak: 0, errorsFixed: fixed }; }
+      recordErrorFixed() { fixed++; }
+    } },
+    './src/moods': {
+      getMoodDisplay: mood => ({ statusText: mood, label: mood, tip: '' }),
+      checkMilestones: () => [],
+      PET_THEMES: { default: { label: 'Default' } }
+    },
+    './src/dashboard': { updateDashboardIfOpen() {} },
+    './src/sidebar': { SidebarProvider: class { update() {} } }
+  };
+  const sandbox = {
+    module: { exports: {} },
+    require: name => { assert.ok(name in dependencies); return dependencies[name]; },
+    setInterval: () => 0,
+    setTimeout: () => 0,
+    clearInterval() {},
+    clearTimeout() {}
+  };
+  vm.runInNewContext(fs.readFileSync(path.join(__dirname, '..', 'extension.js'), 'utf8'), sandbox);
+  sandbox.module.exports.activate({ subscriptions: [] });
+
+  onDiagnostics();
+  assert.equal(calls.length, 1, 'split editors must not double-count one document');
+  assert.match(statusBar.text, /struggling/);
+
+  diagnostics = [];
+  onDiagnostics();
+  assert.equal(fixed, 1, 'warnings must not count as fixed errors');
+  assert.match(statusBar.text, /focused/);
+
+  calls.length = 0;
+  vscode.window.visibleTextEditors = [];
+  onDiagnostics();
+  assert.equal(calls.length, 0, 'no editor means no diagnostic query');
+  assert.equal(fixed, 1);
+});