Matrix digital rain · kimi-k3

Let me build the Matrix rain in a single index.html, then test with browser tool.

Canvas is black on the initial frame — the screenshot was taken at frame 1, before any ticks (drops start above screen). Need to wait / sample motion frames. Use motion action to capture several frames.

The animation is running: multiple columns, bright leading glyphs (whitish), fading trails, varying speeds. Some glyphs show as boxes — likely katakana glyphs not available in local monospace font (tofu). Some columns show repeated glyphs because trail chars cached... Actually the repeated pattern "ホホホ" suggests trail glyph cache works but the chars array is short. Actually the cache: `if (d.chars.length === 0 || d.chars.length < d.trail + 1) d.chars.push(randomGlyph());` — this pushes only ONE glyph per tick, and d.trail can be 21. But the trail drawn uses chars[t % chars.length], so early on the pattern repeats. Over many ticks it fills. But also mutation only 15% chance. The long columns with same repeated glyph (e.g., "ホホホホ") come from short cache repeating. Better to fill the cache fully on first use. Let me fix: fill chars array to trail+1 immediately.

Also tofu boxes — some glyphs like ╌ or ¦ may not render; the GLYPHS string includes "¦｜╌" which may be missing in local font. Also the katakana render fine mostly. Boxes appear in a few columns — could be digits fine... Boxes appear frequently in some columns, suggesting specific chars (like ╌ U+254C) render as tofu. Remove the unusual symbols, keep katakana + digits + common ASCII.

Fix both issues.

Oops, my first edit included a bogus key "newText_placeholder" — actually I passed both newText and newText_placeholder? No, I passed newText twice? Let me check: the edit object had "oldText", "newText" set to the shorter string, and an extra key "newText_placeholder" with empty string. Extra keys may be ignored, but let me verify the file is correct.

Edits applied correctly. Now reload and test Pause/Resume and Restart.

Still some tofu boxes appear in certain columns (e.g., column with ☐ repeated). The remaining glyphs are katakana + digits + "Z:.=+*<>". Hmm, boxes like "ロ" could actually be ロ (katakana ro) which looks like a box! Indeed ロ looks like a hollow square — that's a legit glyph, not tofu. Yes, "ロ" is katakana "ro". So it's fine.

Trails still look repetitive (e.g., long runs of same glyph) — that's because cache persists and mutation is only 15%. It looks OK aesthetically — classic matrix effects often mutate glyphs. Actually the repetition comes from... wait, the trail glyph for position t uses chars[t % chars.length], and chars has trail+1 entries, so each row has its own glyph. But looking at screenshots, columns show long runs of the same glyph (e.g., "ハハハハ"). Hmm. That's because the drop moves down by speed rows per tick, and the head at row headRow shows chars[0] every tick — so the same glyph is drawn at successive rows as it moves down. As the fade doesn't fully erase, the previously drawn head glyph stays bright for a few frames... Actually the head draws chars[0] at new row each tick, so consecutive rows get the same bright glyph, producing runs of identical glyphs. To fix, rotate chars so head glyph changes: shift a new glyph onto chars each tick (unshift) and pop. But then trail glyphs shift with it — that's actually correct: chars[1] is the glyph one row behind head. If we unshift a new head glyph each tick, the old head becomes trail[1], matching motion when speed ≈ 1 row/tick. With fractional speed < 1, head may stay on same row for multiple ticks — fine.

But wait, speed varies 0.35–1.4 rows/tick, so row advance isn't exactly 1. Simpler approach: each tick, if floor(d.y) changed since last tick, unshift new glyphs per row advanced. That gives each row a distinct glyph. Let's implement: track lastRow; when head advances by k rows, unshift k new random glyphs and trim to trail+1. Also occasional mutation of trail glyphs for shimmer.

Let me update the code.

Much better — distinct glyphs per row, bright white leading glyphs with glow, fading green trails, varied column lengths/speeds. Now test Pause: click Pause, take two screenshots at different times, verify image frozen; then Resume; then Restart to verify canvas cleared.

Pause clicked — button now says "Resume". Verify image stays frozen by taking two screenshots with delay between them.

All 4 frames identical — pause freezes the image. Now resume and check motion continues.

Resume works — animation continues (note: first resume frame looked like the layout restarted to fresh state... Actually the first frame after resume shows a fresh-looking rain, but that's because during the pause the screenshot/motion capture may have reloaded? No — the resume click frame matched the paused frame exactly, and the motion after shows it moving. Good.)

Now test Restart: click Restart, screenshot should show black canvas (cleared trails), then rain rebuilds.

Restart cleared the canvas fully to black (old trails gone). Now confirm rain rebuilds after restart.

Restart verified: canvas cleared to black, rain rebuilt with fresh columns. All requirements verified except resize — I could test resize but the browser tool viewport is fixed at 1200×800; the scroll/drag tools can't resize the window. The resize handler rebuilds layout with devicePixelRatio and repaints black, which is sound code. I'll note it as unverified.

Done. Final file is in place. Report.