LlamaCasty/MyMistakes.md

MyMistakes.md

Two jobs, distinguished by heading:

1. Per-task failure log — updated before every commit touching that task: current iteration + why the last one failed. On task complete, committed AND pushed → truncate to this stub. A new task does NOT seed this file until its first failure.
2. Recipes registry (DERIVED-SOLUTION RULE, see AGENTS.md 🔬) — the durable home for one-off derived solutions, recipes, and how-tos. The moment you work out a reusable solution, write it here in the same session. GREP THIS FILE FIRST when you hit a "I've done this before but have to figure it out again" wall. Recipe entries stay permanently (they are NOT truncated on task completion) — only the failure log truncates.

🔬 Recipes registry

Shrink / re-encode an image for the README (screenshots → small hero image)

Worked out 2026-08-29 (the recipe was NEVER recorded the first time it was done, so it had to be re-derived from scratch — that's the incident this entry exists to end).

Approach: a throwaway Windows-dotnet console app uses WPF's imaging stack (System.Windows.Media.Imaging) — same framework the app runs on, zero NuGet packages, high-quality downscale via TransformedBitmap. Screenshots compress far smaller as JPEG than PNG (PNG 1400px = ~1.2MB; JPEG q82 1400px = ~188KB).

Recipe (run via the Windows dotnet host from WSL):

1. Create imgresize.csproj targeting net8.0-windows with <UseWPF>true</UseWPF> (SDK controller). Put it in a Windows-visible temp path, e.g. C:\Users\gramp\AppData\Local\Temp\imgresize — NOT /tmp (Windows dotnet can't reach a Linux-only path reliably).
2. Program.cs: load BitmapImage (CacheOption=OnLoad → Freeze()), downscale with TransformedBitmap(src, new ScaleTransform(scale, scale)) to max width (1400 for the README hero), encode with JpegBitmapEncoder { QualityLevel = 82 }, save.
3. Run:

"/mnt/c/Program Files/dotnet/dotnet.exe" run -c Release --project .
   -- "C:\Users\gramp\Downloads\Screenshot 2026-08-29 075626.png"
      "C:\Users\gramp\Documents\Code\projects\ytLive\docs\ytLlive-preview.jpg" 1400

4. Point README.md at the .jpg (not .png).

Result: 3.2MB screenshot → 1400×794 → 188KB ytLlive-preview.jpg in docs/.

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Splitting a large file into partials — NEVER awk … > SRC while awking SRC

(2026-08-31, Commit D) Tried to split SocialsDialogViewModel.cs in one line: { awk '…' SRC; echo ""; awk '…2…' SRC; } > SRC. The first write truncated SRC to 1 line, so the second awk read the already-truncated file → the whole source was lost (1 line left). Recovered with git checkout -- SRC, then redid it, but the same bug could have meant making it up from scratch.

Rule: when a cut needs N blocks from one source into N files, never write a block back onto the source that the awks still read. Instead:

1. Read the source once at the start into temp files (mktemp -d, one file per block), with a $D variable you carry forward.
2. Verify block sizes (wc -l) and brace balance (python3 -c counting {/}) before touching any real file.
3. Then assemble each new file from cat D/block … — never truncating the source until every read is done.

git status can't save you here if you don't notice until the file is gone — git checkout -- <path> from the last commit is the recovery. Cheap insurance: restore-then-retry, do it atomically from temp files the first time.