fix(electrobun): address all 20 Codex review findings

CRITICAL:
- PTY leak: Terminal.svelte now calls pty.close on destroy, not just unsubscribe
- Agent session cleanup: clearSession() removes done/error sessions, backend
  deletes after 60s grace period

HIGH:
- Clone branch passthrough: user's branch name flows through callback
- Circular imports: extracted rpc.ts singleton, broke main.ts ↔ App.svelte cycle
- Settings wired to runtime: Terminal reads cursor/scrollback from settings
- Security disclaimer: added "prototype — not system keyring" notice
- ThemeEditor: fixed basePalette → initialPalette reference

MEDIUM:
- Clone race: UUID suffix instead of count-based index
- Silent failures: structured error returns from PTY handlers
- WebKitGTK mount: only current + previous group mounted
- Debug listeners: gated behind DEBUG, cleanup on destroy
- NDJSON residual buffer parsed on process exit
- Codex adapter: deduplicated tool_call/tool_result
- extraEnv: rejects CLAUDE*/CODEX*/OLLAMA* keys
- settings-db: runMigrations() with version tracking
- active_group: persisted via settings.set

LOW:
- Removed dead demo code, unused variables
- color-mix() fallbacks added

ui-electrobun/src/bun/sidecar-manager.ts

@@ -41,11 +41,25 @@ interface ActiveSession {
   onStatus: StatusCallback[];
 }
 
-// ── Environment stripping ────────────────────────────────────────────────────
+// ── Environment stripping (Fix #14) ──────────────────────────────────────────
 
 const STRIP_PREFIXES = ["CLAUDE", "CODEX", "OLLAMA", "ANTHROPIC_"];
 const WHITELIST_PREFIXES = ["CLAUDE_CODE_EXPERIMENTAL_"];
 
+function validateExtraEnv(extraEnv: Record<string, string> | undefined): Record<string, string> | undefined {
+  if (!extraEnv) return undefined;
+  const clean: Record<string, string> = {};
+  for (const [key, value] of Object.entries(extraEnv)) {
+    const blocked = STRIP_PREFIXES.some((p) => key.startsWith(p));
+    if (blocked) {
+      console.warn(`[sidecar] Rejected extraEnv key "${key}" — provider-prefixed keys not allowed`);
+      continue;
+    }
+    clean[key] = value;
+  }
+  return Object.keys(clean).length > 0 ? clean : undefined;
+}
+
 function buildCleanEnv(extraEnv?: Record<string, string>, claudeConfigDir?: string): Record<string, string> {
   const clean: Record<string, string> = {};
 
@@ -61,8 +75,10 @@ function buildCleanEnv(extraEnv?: Record<string, string>, claudeConfigDir?: stri
   if (claudeConfigDir) {
     clean["CLAUDE_CONFIG_DIR"] = claudeConfigDir;
   }
-  if (extraEnv) {
-    Object.assign(clean, extraEnv);
+  // Apply validated extraEnv
+  const validated = validateExtraEnv(extraEnv);
+  if (validated) {
+    Object.assign(clean, validated);
   }
 
   return clean;
@@ -93,13 +109,11 @@ function findClaudeCli(): string | undefined {
 // ── Runner resolution ────────────────────────────────────────────────────────
 
 function resolveRunnerPath(provider: ProviderId): string {
-  // Sidecar runners live in the repo's sidecar/dist/ directory
   const repoRoot = join(import.meta.dir, "..", "..", "..");
   return join(repoRoot, "sidecar", "dist", `${provider}-runner.mjs`);
 }
 
 function findNodeRuntime(): string {
-  // Prefer Deno, fallback to Node.js (matching Tauri sidecar behavior)
   try {
     const result = Bun.spawnSync(["which", "deno"]);
     const path = new TextDecoder().decode(result.stdout).trim();
@@ -115,10 +129,15 @@ function findNodeRuntime(): string {
   return "node"; // last resort
 }
 
+// ── Cleanup grace period ─────────────────────────────────────────────────────
+
+const CLEANUP_GRACE_MS = 60_000; // 60s after done/error before removing session
+
 // ── SidecarManager ───────────────────────────────────────────────────────────
 
 export class SidecarManager {
   private sessions = new Map<string, ActiveSession>();
+  private cleanupTimers = new Map<string, ReturnType<typeof setTimeout>>();
   private claudePath: string | undefined;
   private nodeRuntime: string;
 
@@ -197,6 +216,8 @@ export class SidecarManager {
       if (s) {
         s.state.status = exitCode === 0 ? "done" : "error";
         this.emitStatus(sessionId, s.state.status, exitCode !== 0 ? `Exit code: ${exitCode}` : undefined);
+        // Schedule cleanup (Fix #2)
+        this.scheduleCleanup(sessionId);
       }
     });
 
@@ -211,7 +232,7 @@ export class SidecarManager {
       maxTurns: options.maxTurns,
       permissionMode: options.permissionMode ?? "bypassPermissions",
       claudeConfigDir: options.claudeConfigDir,
-      extraEnv: options.extraEnv,
+      extraEnv: validateExtraEnv(options.extraEnv),
     };
 
     this.writeToProcess(sessionId, queryMsg);
@@ -236,7 +257,7 @@ export class SidecarManager {
         s.controller.abort();
         s.state.status = "done";
         this.emitStatus(sessionId, "done");
-        this.sessions.delete(sessionId);
+        this.scheduleCleanup(sessionId);
       }
     }, 3000);
 
@@ -290,6 +311,30 @@ export class SidecarManager {
       }
       this.sessions.delete(sessionId);
     }
+    // Cancel any cleanup timer
+    const timer = this.cleanupTimers.get(sessionId);
+    if (timer) {
+      clearTimeout(timer);
+      this.cleanupTimers.delete(sessionId);
+    }
+  }
+
+  // ── Cleanup scheduling (Fix #2) ─────────────────────────────────────────
+
+  private scheduleCleanup(sessionId: string): void {
+    // Cancel any existing timer
+    const existing = this.cleanupTimers.get(sessionId);
+    if (existing) clearTimeout(existing);
+
+    const timer = setTimeout(() => {
+      this.cleanupTimers.delete(sessionId);
+      const session = this.sessions.get(sessionId);
+      if (session && (session.state.status === "done" || session.state.status === "error")) {
+        this.sessions.delete(sessionId);
+      }
+    }, CLEANUP_GRACE_MS);
+
+    this.cleanupTimers.set(sessionId, timer);
   }
 
   // ── Internal ───────────────────────────────────────────────────────────────
@@ -324,6 +369,12 @@ export class SidecarManager {
           this.handleNdjsonLine(sessionId, session, line);
         }
       }
+
+      // Fix #12: Parse any residual data left in the buffer after stream ends
+      const residual = buffer.trim();
+      if (residual) {
+        this.handleNdjsonLine(sessionId, session, residual);
+      }
     } catch (err) {
       // Stream closed — expected on process exit
       if (!session.controller.signal.aborted) {
@@ -339,7 +390,6 @@ export class SidecarManager {
     try {
       for await (const chunk of reader) {
         const text = decoder.decode(chunk, { stream: true });
-        // Log sidecar stderr as debug output
         for (const line of text.split("\n")) {
           if (line.trim()) {
             console.log(`[sidecar:${sessionId}] ${line.trim()}`);