Hardening + collaboration features from full app review

Security and robustness (backend):
- Strict CSP (was null); confine read_file/launch_file/ue_log to the client root
- p4 trust without -f: surface fingerprint CHANGES instead of auto-accepting (MITM)
- stdin=null by default + non-interactive P4EDITOR so terminal commands never hang
- 64 MB read caps on read_depot/read_file/print_depot (no OOM on huge .uasset/.pak)
- Recover from mutex poisoning instead of crashing every later p4 call
- Decode p4 output as UTF-8 then cp1251 (Cyrillic paths no longer corrupt)
- p4_changes never deletes changelists that hold shelved files
- Validate changelist number in p4_undo_change

Bug fixes (frontend):
- Focus-refresh preserves the checkbox selection (never re-checks deselected files)
- Staleness guards on refresh/describe/AI-summary/user-groups (no cross-selection races)
- Real F5/Ctrl+R/G/S/B handlers; match e.code so Ctrl+backquote works on RU layout
- Confirm dialog no longer fires on a stray global Enter
- Panel/dock/history drags end on window blur (no stuck resize)
- Commit draft clears on Submit only if unchanged since committing
- Summary/IDE buttons gated to real source files (not .pak/.dll/binaries)

New features:
- Exclusive lock/unlock plus held-by/locked-by indicators (p4 opened -a)
- Shelve/unshelve/delete-shelf on pending changelists
- Resolve UI (auto-merge / accept yours / accept theirs, per file or all) + banner
- Diff a history revision against the previous one; blame/annotate view
- Depot file search (Tools -> Search depot)
- Move opened files between pending changelists
- New-submit toasts from teammates + offline banner with auto-reconnect

Also: bake OpenRouter key at build time (git-ignored), drop AI settings UI,
IDE picker (detect installed editors), AI replies in the UI language,
persistent code summaries, metadata/CSP polish.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/ai.ts

@@ -1,37 +1,33 @@
 // OpenRouter-powered commit summary + small avatar helpers.
 import { p4, OpenedFile, statusOf } from "./p4";
+import { LANG } from "./i18n";
 
-const MODEL_KEY = "exd-ai-model";
-const KEY_KEY = "exd-ai-key";
-// cheap + reliable default; change to a "…:free" model in Settings to pay nothing
+// AI replies follow the app's UI language
+const LANG_NAMES: Record<string, string> = { en: "English", ru: "Russian", de: "German", fr: "French", es: "Spanish" };
+function langName(): string { return LANG_NAMES[LANG] || "English"; }
+
+// fixed model — no user-facing AI settings
 export const DEFAULT_MODEL = "openai/gpt-4o-mini";
 
-export function getModel(): string { try { return localStorage.getItem(MODEL_KEY) || DEFAULT_MODEL; } catch { return DEFAULT_MODEL; } }
-export function setModel(m: string) { try { localStorage.setItem(MODEL_KEY, m.trim() || DEFAULT_MODEL); } catch {} }
-export function getKeyLocal(): string { try { return localStorage.getItem(KEY_KEY) || ""; } catch { return ""; } }
-export function setKeyLocal(k: string) { try { localStorage.setItem(KEY_KEY, k.trim()); } catch {} }
-
-// key resolution: localStorage first, else the app-config file (git-ignored)
+// the key is baked into the binary at build time (src-tauri/openrouter.key)
 export async function resolveKey(): Promise<string> {
-  const local = getKeyLocal();
-  if (local) return local;
   try { return (await p4.readAiKey()) || ""; } catch { return ""; }
 }
 
 // generate a commit summary + description from the changed files
 export async function aiSummary(files: OpenedFile[]): Promise<{ summary: string; description: string }> {
   const key = await resolveKey();
-  if (!key) throw new Error("No OpenRouter API key — set it in Settings");
+  if (!key) throw new Error("No OpenRouter API key baked into this build");
   const list = files.slice(0, 200).map((f) => `${statusOf(f.action).ch} ${f.depotFile || ""}`).join("\n");
   const res = await fetch("https://openrouter.ai/api/v1/chat/completions", {
     method: "POST",
     headers: { Authorization: `Bearer ${key}`, "Content-Type": "application/json", "X-Title": "Exbyte Depot" },
     body: JSON.stringify({
-      model: getModel(),
+      model: DEFAULT_MODEL,
       max_tokens: 300,
       temperature: 0.3,
       messages: [
-        { role: "system", content: "You write concise commit messages for a Perforce/Unreal project. Given a list of changed files (+ added, ± edited, − deleted), reply with ONE short imperative summary line (under 72 chars, no trailing period), then a blank line, then an optional 1-3 line description. Plain text only — no markdown, no code fences, no quotes." },
+        { role: "system", content: `You write concise commit messages for a Perforce/Unreal project. Given a list of changed files (+ added, ± edited, − deleted), reply with ONE short imperative summary line (under 72 chars, no trailing period), then a blank line, then an optional 1-3 line description. Plain text only — no markdown, no code fences, no quotes. Write the entire reply in ${langName()}.` },
         { role: "user", content: `Changed files:\n${list}` },
       ],
     }),
@@ -49,6 +45,53 @@ export async function aiSummary(files: OpenedFile[]): Promise<{ summary: string;
   return { summary, description };
 }
 
+// briefly explain what a source file does (2–4 sentences, plain text)
+export async function aiExplainCode(name: string, code: string): Promise<string> {
+  const key = await resolveKey();
+  if (!key) throw new Error("No OpenRouter API key baked into this build");
+  const snippet = code.slice(0, 14000); // cap the payload
+  const res = await fetch("https://openrouter.ai/api/v1/chat/completions", {
+    method: "POST",
+    headers: { Authorization: `Bearer ${key}`, "Content-Type": "application/json", "X-Title": "Exbyte Depot" },
+    body: JSON.stringify({
+      model: DEFAULT_MODEL,
+      max_tokens: 260,
+      temperature: 0.2,
+      messages: [
+        { role: "system", content: `You explain source files for a Perforce/Unreal C++ (and general game) project. Given one file, reply with a SHORT plain-text summary (2–4 sentences) of what it does and its role in the project. No markdown, no code fences, no headings, no bullet points — a single tight paragraph. Write the entire reply in ${langName()}.` },
+        { role: "user", content: `File: ${name}\n\n${snippet}` },
+      ],
+    }),
+  });
+  if (!res.ok) {
+    const txt = await res.text().catch(() => "");
+    throw new Error(`OpenRouter ${res.status}: ${txt.slice(0, 180)}`);
+  }
+  const data = await res.json();
+  const content: string = (data?.choices?.[0]?.message?.content || "").trim();
+  if (!content) throw new Error("Empty AI response");
+  return content;
+}
+
+// --- persistent cache of AI code summaries (removed only via the × button) ---
+const EXPL_KEY = "exd-explain";
+type ExplEntry = { k: string; v: string };
+function loadExpl(): ExplEntry[] {
+  try { const r = localStorage.getItem(EXPL_KEY); const l = r ? JSON.parse(r) : []; return Array.isArray(l) ? l : []; } catch { return []; }
+}
+function storeExpl(list: ExplEntry[]) { try { localStorage.setItem(EXPL_KEY, JSON.stringify(list)); } catch {} }
+export function getExplain(key: string): string | null {
+  return loadExpl().find((e) => e.k === key)?.v ?? null;
+}
+export function saveExplain(key: string, text: string) {
+  const list = loadExpl().filter((e) => e.k !== key);
+  list.push({ k: key, v: text });
+  storeExpl(list.slice(-80)); // keep the 80 most recent
+}
+export function dropExplain(key: string) {
+  storeExpl(loadExpl().filter((e) => e.k !== key));
+}
+
 // --- avatar helpers ---
 export function initials(name: string, user: string): string {
   const n = (name || "").trim();