feat(admin): live log viewer and searcher in log files page

[Rhefew]

Live Log Viewer & Searcher in Admin Panel

Implements an in-browser live log viewer and search tool directly within the Admin Panel's Log Files page.

Key Features

1. Side-by-Side Layout: Selecting a log file resizes the file table and displays the terminal alongside it without leaving the page.
2. Live Auto-Refresh: Switchable live mode that automatically pulls incoming log entries every 2 seconds.
3. Instant Search & Filter: Filter log entries in real-time by text (case-insensitive) with matching highlight styling.
4. Log Level Color Coding:
   • Errors / Critical: Red bold text
   • Warnings: Yellow text
   • Debug: Muted italic text
   • Information: Green text
5. Auto-Scroll & Fast Read: Reads the trailing lines of the target log file and automatically scrolls down to the newest entries upon refresh.

Code Quality & Guidelines

• Uses static helper methods for string formatting and line parsing.
• Adheres to OpenMU this. qualification standards and ConfigureAwait(false) async conventions.
• Zero compiler warnings or errors.

[sven-n]

Review

Scope: single file, src/Web/AdminPanel/Pages/LogFiles.razor (+322/−37). Adds a side-by-side log terminal with live polling, text filter, level color coding, and a download action; also rewrites the file-list load into a refreshable method and fixes FormatFileSize.

Nice work overall — the FormatFileSize rewrite is a genuine bug fix (the old < 1024 << 10 switch mislabeled small files as KiB and had a dead bytes arm), and reading only the trailing 100 KB is the right instinct for a 4 MiB rolling log. The level tokens ([Error], [Warning], [Information], [Debug]) do match the Serilog outputTemplate in src/Startup/appsettings.json, so the coloring will actually fire.

Correctness / behavior

• Forced scroll breaks live reading. RefreshLogLines sets _shouldScrollToBottom = true unconditionally, and the timer calls it every 2 s. A user who scrolls up to read history gets yanked to the bottom every two seconds. Only auto-scroll when the terminal was already at (or near) the bottom, or only on initial select.
• Disposal race. Dispose() disposes the timer, but a callback already in flight can still call InvokeAsync(...) on a disposed component → ObjectDisposedException on the renderer. Add a _disposed guard (or a CancellationTokenSource) checked inside the callback, and prefer PeriodicTimer in a background loop over System.Threading.Timer.
• SetupTimer uses ??=, so toggling live update twice is safe, but the period/dueTime is never re-armed. Minor today; fragile if the interval becomes configurable.
• Blocking file I/O on the render/timer path. ReadLastLines is fully synchronous and runs from SelectFile (UI circuit) and from the timer. On a slow or remote disk this stalls the circuit. The convention elsewhere in the repo is async; use async reads and make the handlers async Task.
• ConfigureAwait(false) in a component is actually the wrong convention inside Blazor components — it drops the renderer's synchronization context. It happens to be harmless here (nothing follows the awaits), but the PR description claims it as adherence to project conventions; it isn't.
• Multi-line exceptions lose their color and their filter context. {Exception} stack traces are separate lines with no [Level] token, so they render in the default gray, and a text filter shows a matching stack frame with no header line. Consider grouping a header line with its continuation lines.
• Broad catches. ReadLastLines catches Exception and injects "Error reading log file: {ex.Message}" into the log data — better to surface that in a distinct UI error field. ScrollToBottomAsync's bare catch { } should be narrowed to JSDisconnectedException (plus TaskCanceledException) so real interop errors aren't silently swallowed.

Performance

• GetFilteredLines() is called twice per render (once for the list, once for the "Showing X of Y" counter), each allocating a new List<string>. With live mode that's two full scans plus two allocations every 2 s, plus one per keystroke in the filter box. Compute once into a field on refresh / search change.
• The timer calls StateHasChanged() unconditionally, re-diffing 300 <div>s even when the file hasn't changed. Cheap guard: skip if FileInfo.Length / LastWriteTimeUtc is unchanged.

Project conventions

• Localization regression. The page previously used Resources.FileName / LastUpdate / Size throughout; the new UI hardcodes English: "Log Files", "Actions", "Log Viewer:", "Live", "Refresh", "Close", "Filter log entries...", "No log entries found.", "No log entries match your filter.", "Showing ... lines", and every title=. These belong in Properties/Resources.resx (and the translated variants). This is probably the main blocker.
• JSRuntime.InvokeVoidAsync("eval", ...) is a smell and CSP-hostile. Define a small JS function (or use an ElementReference plus a module in a .razor.js) instead of shipping eval.
• BOM removed from line 1 (-@page → @page). Every other .razor in the repo is UTF-8-with-BOM; this makes the change show up as a whole-file rewrite in some tools. Please restore it.
• Heavy inline styles (style="color: #ff6b6b...", hardcoded hex backgrounds, !important) rather than CSS classes. Moving these to the site stylesheet keeps theming consistent and the markup readable.
• Magic numbers 102400, 300, 2000 are duplicated between code and the user-visible string "Last 300 lines loaded" — hoist them to private const.

Security

• No path traversal: the file is chosen from a server-enumerated FileInfo, never from user-supplied text. Good.
• Log content is rendered as text via @line, so Razor escapes it — no XSS from log payloads. Good.
• The page inherits the Admin Panel's existing auth, but note it now streams log contents rather than just linking files; worth confirming the panel is authenticated in the targeted deployments. Not something this PR introduces.
• The description mentions "matching highlight styling" for search hits, but the diff only implements filtering. Either implement highlighting (escaping carefully before injecting <mark>) or drop the claim.

Tests

No tests. There is no existing Blazor test project, so this matches the status quo, but FormatFileSize and ReadLastLines are static and nearly pure — extracting them into a small helper class would allow covering the boundary cases (0 bytes, exactly 1024, file shorter than 100 KB, offset landing mid-line).

Suggested must-fix before merge

1. Localize all new strings via Resources.
2. Replace the eval interop with a named JS function.
3. Guard disposal in the timer callback; stop force-scrolling on every live refresh.
4. Cache GetFilteredLines() instead of calling it twice per render.
5. Restore the UTF-8 BOM.

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