fix(plugin): safe recording start — no mid-game config rewrite, scoped log clear

plugins/decky-vault/main.py

@@ -367,20 +367,56 @@ exec mangohud "$@"
             return {"error": f"Failed to read log: {str(e)}"}
 
     async def clear_mangohud_log(self) -> dict:
-        """RPC: Delete all MangoHud log files in /tmp/ so the next recording starts fresh."""
+        """RPC: Delete stale MangoHud log files in /tmp/ so the next recording
+        starts fresh. Only touches files whose name contains 'MangoHud'; never
+        bare /tmp/*.log or /tmp/*.csv. Skips files modified in the last 3s
+        (an active session may still have them open)."""
         import glob
+        import time
+        RECENT_WINDOW_S = 3
+        now = time.time()
+        deleted, skipped = [], []
         try:
-            for pattern in ["/tmp/*MangoHud*", "/tmp/*.csv", "/tmp/*.log"]:
+            for pattern in ["/tmp/*MangoHud*"]:
                 for f in glob.glob(pattern):
-                    if os.path.isfile(f):
-                        try:
-                            os.remove(f)
-                        except (IOError, PermissionError):
-                            pass
-            return {"success": True}
+                    if not os.path.isfile(f):
+                        continue
+                    try:
+                        if now - os.path.getmtime(f) < RECENT_WINDOW_S:
+                            skipped.append({"name": os.path.basename(f), "reason": "active"})
+                            continue
+                        os.remove(f)
+                        deleted.append({"name": os.path.basename(f)})
+                    except (IOError, PermissionError):
+                        skipped.append({"name": os.path.basename(f), "reason": "perm"})
+            return {"success": True, "deleted": deleted, "skipped": skipped}
+        except Exception as e:
+            return {"success": False, "error": str(e), "deleted": deleted, "skipped": skipped}
+
+    async def delete_log_file(self, path: str) -> dict:
+        """RPC: Delete a single, specific MangoHud log file. The path must be
+        under /tmp and its basename must contain 'MangoHud'. Defence in depth
+        so a bad/stale path can never delete unrelated files."""
+        try:
+            if not path:
+                return {"success": False, "error": "No path provided"}
+            abs_path = os.path.abspath(path)
+            if not abs_path.startswith("/tmp/"):
+                return {"success": False, "error": "Refusing to delete file outside /tmp"}
+            if "MangoHud" not in os.path.basename(abs_path):
+                return {"success": False, "error": "Refusing to delete non-MangoHud file"}
+            if not os.path.exists(abs_path):
+                return {"success": True, "deleted": False, "note": "already gone"}
+            os.remove(abs_path)
+            return {"success": True, "deleted": True, "path": abs_path}
         except Exception as e:
             return {"success": False, "error": str(e)}
 
+    async def find_mangohud_log(self) -> dict:
+        """RPC: Return the path of the most recent MangoHud log in /tmp/, or null."""
+        path = await self._find_mangohud_log()
+        return {"path": path}
+
     async def get_hardware_info(self) -> dict:
         """RPC: Detect hardware model from DMI. Returns {slug, name, raw}."""
         # Steam Deck models: Jupiter = LCD, Galileo = OLED

plugins/decky-vault/src/index.tsx

@@ -12,7 +12,8 @@ import { useSettings, useSession, useGameDetection } from "./lib/store"
 import {
   readAndParseMangohudLog,
   clearMangohudLog,
-  writeMangohudConfig,
+  deleteLogFile,
+  findMangohudLog,
   startMangohudLogging,
   stopMangohudLogging,
   getHardwareInfo,
@@ -37,6 +38,7 @@ function Content() {
     onGameStart,
     onGameStop,
     setGameName,
+    setLastLogPath,
   } = useSession()
 
   // ── Game detection via polling ────────────────────────────────
@@ -44,10 +46,13 @@ function Content() {
 
   // ── Handle start recording ────────────────────────────────────
   async function handleStart() {
-    // Write MangoHud config with logging settings
-    await writeMangohudConfig()
-    // Clear any previous log file
-    await clearMangohudLog()
+    // Clear the previous session's specific log if we know it; else safe-clear.
+    const prev = session.lastLogPath
+    if (prev) {
+      await deleteLogFile(prev)
+    } else {
+      await clearMangohudLog()
+    }
     // Fire-and-forget: try to start MangoHud logging (retries until game launches)
     startMangohudLogging()
     startRecording()
@@ -60,12 +65,14 @@ function Content() {
       await stopMangohudLogging()
       stopRecording()
 
-      // Parse the MangoHud log
-      const logResult = await readAndParseMangohudLog()
+      // Find the most recent MangoHud log, parse it, remember its path
+      const logPath = await findMangohudLog()
+      const logResult = await readAndParseMangohudLog(logPath.path ?? undefined)
       if (logResult.error) {
         setError(logResult.error)
         return
       }
+      setLastLogPath(logPath.path ?? null)
 
       // Read system info in parallel
       const [hwInfo, osVersion] = await Promise.all([

plugins/decky-vault/src/lib/api.ts

@@ -36,9 +36,21 @@ export const readAndParseMangohudLog = callable<[logPath?: string], {
 
 export const clearMangohudLog = callable<[], {
   success: boolean
+  deleted?: Array<{ name: string }>
+  skipped?: Array<{ name: string; reason: string }>
   error?: string
 }>("clear_mangohud_log")
 
+export const deleteLogFile = callable<[path: string], {
+  success: boolean
+  deleted?: boolean
+  error?: string
+}>("delete_log_file")
+
+export const findMangohudLog = callable<[], {
+  path: string | null
+}>("find_mangohud_log")
+
 export const startMangohudLogging = callable<[], {
   success: boolean
   error?: string

plugins/decky-vault/src/lib/store.ts

@@ -36,6 +36,8 @@ export interface SessionData {
   protonVersion: string
   versionString: string
   buildId: string
+  // Path of the MangoHud log captured for this session (for targeted cleanup on restart)
+  lastLogPath: string | null
   // Manual inputs (filled by user in the form)
   upscalerType: string
   upscalerVersion: string
@@ -70,6 +72,7 @@ function createEmptySession(): SessionData {
     protonVersion: "",
     versionString: "",
     buildId: "",
+    lastLogPath: null,
     upscalerType: "none",
     upscalerVersion: "",
     frameGenMethod: "none",
@@ -182,6 +185,10 @@ export function useSession() {
     setSession((prev) => ({ ...prev, gameName: name, appId: appId ?? prev.appId }))
   }, [])
 
+  const setLastLogPath = useCallback((p: string | null) => {
+    setSession((prev) => ({ ...prev, lastLogPath: p }))
+  }, [])
+
   return {
     recordingState,
     session,
@@ -196,6 +203,7 @@ export function useSession() {
     onGameStart,
     onGameStop,
     setGameName,
+    setLastLogPath,
   }
 }
 

plugins/decky-vault/tests/test_clear_log.py

@@ -0,0 +1,87 @@
+"""Tests for safe MangoHud log clearing (Bug 1 fix)."""
+import os
+import tempfile
+import time
+import pytest
+
+
+def _touch(path, mtime_age=10):
+    """Create a file at path, optionally backdated mtime by mtime_age seconds."""
+    os.makedirs(os.path.dirname(path), exist_ok=True)
+    with open(path, "w") as f:
+        f.write("data")
+    if mtime_age > 0:
+        t = time.time() - mtime_age
+        os.utime(path, (t, t))
+
+
+def _safe_clear_mangohud_logs(tmpdir, now=None, recent_window_s=3):
+    """Mirror of Plugin.clear_mangohud_log safe logic, operating on tmpdir."""
+    import glob
+    if now is None:
+        now = time.time()
+    deleted, skipped = [], []
+    patterns = [
+        os.path.join(tmpdir, "*MangoHud*"),
+    ]
+    for pat in patterns:
+        for f in glob.glob(pat):
+            if not os.path.isfile(f):
+                continue
+            try:
+                if now - os.path.getmtime(f) < recent_window_s:
+                    skipped.append({"name": os.path.basename(f), "reason": "active"})
+                    continue
+                os.remove(f)
+                deleted.append({"name": os.path.basename(f)})
+            except (IOError, PermissionError):
+                skipped.append({"name": os.path.basename(f), "reason": "perm"})
+    return {"success": True, "deleted": deleted, "skipped": skipped}
+
+
+def test_only_mangohud_files_removed():
+    with tempfile.TemporaryDirectory() as tmp:
+        _touch(os.path.join(tmp, "MangoHud-1.csv"), mtime_age=10)
+        _touch(os.path.join(tmp, "system.log"), mtime_age=10)       # MUST be untouched
+        _touch(os.path.join(tmp, "other.csv"), mtime_age=10)        # MUST be untouched
+        res = _safe_clear_mangohud_logs(tmp)
+        assert res["success"] is True
+        names = [d["name"] for d in res["deleted"]]
+        assert "MangoHud-1.csv" in names
+        assert "system.log" not in names and "other.csv" not in names
+        assert os.path.exists(os.path.join(tmp, "system.log"))
+        assert os.path.exists(os.path.join(tmp, "other.csv"))
+
+
+def test_active_recent_file_skipped():
+    with tempfile.TemporaryDirectory() as tmp:
+        _touch(os.path.join(tmp, "MangoHud-active.csv"), mtime_age=0)
+        res = _safe_clear_mangohud_logs(tmp)
+        assert res["deleted"] == []
+        assert any(s["name"] == "MangoHud-active.csv" for s in res["skipped"])
+        assert os.path.exists(os.path.join(tmp, "MangoHud-active.csv"))
+
+
+def _validate_log_path(path, tmpdir):
+    """Mirror of Plugin.delete_log_file path validation."""
+    if not path:
+        return False
+    abs_path = os.path.abspath(path)
+    if not abs_path.startswith(os.path.abspath(tmpdir) + os.sep):
+        return False
+    base = os.path.basename(abs_path)
+    if "MangoHud" not in base:
+        return False
+    return True
+
+
+def test_delete_log_file_rejects_outside_tmp():
+    with tempfile.TemporaryDirectory() as tmp:
+        assert _validate_log_path("/etc/passwd", tmp) is False
+        assert _validate_log_path(os.path.expanduser("~/x.log"), tmp) is False
+
+
+def test_delete_log_file_rejects_non_mangohud():
+    with tempfile.TemporaryDirectory() as tmp:
+        assert _validate_log_path(os.path.join(tmp, "system.log"), tmp) is False
+        assert _validate_log_path(os.path.join(tmp, "MangoHud-1.csv"), tmp) is True