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miniSCP/docs/gotchas.md
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JokinandClaude Fable 5 ef34104cf0 Fix white/inverted flash when windows open
Three layers: windows are created hidden and revealed on the webview's
first dom-ready (800ms fallback); the bun preload bakes the persisted
theme data-attributes so the first paint is already themed; and
index.html carries an inline background style covering the
pre-stylesheet paint (values mirrored from styles.css tokens).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-14 09:17:31 +02:00

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# Gotchas — landmines this codebase has already stepped on
Every one of these caused a real bug or debugging spiral. Read before
touching the adjacent code.
## Angular (v22, zoneless, signals, OnPush)
- **Never consume push streams through signal+effect.** An effect that reads
a signal and (directly or transitively) writes signals re-triggers itself —
this froze the entire app on the first transfer. Push messages
(transferUpdate etc.) go through plain callback registries in RpcService.
Signal coalescing would also silently drop intermediate progress snapshots.
- **No signal writes during template render** (NG0600). Anything that loads
panels from code paths reachable during render defers with
`queueMicrotask` (see `PanelsService.newWorkspace`).
- **`[value]` on `<select>` is applied before `@for` options render** and
silently selects nothing. Use per-option `[selected]` bindings (connection
manager stack picker).
- Template bindings with special characters: `[class.bg-primary/15]` works;
`[class.shadow-[...]]` (brackets) does NOT parse — use `[style.box-shadow]`.
Static class attributes may use arbitrary values freely.
- Functions called from templates ARE reactive: signals read inside them
register on the view's consumer (call-stack-based tracking). That's why
`iconClass(entry)` reacting to `settings.iconColors()` works.
- Dedicated tools > shell: IDE diagnostics between paired template/class
edits are often stale mid-sequence — trust `bun run build:ui` (full AOT
type-check), not the first red squiggle.
- Tailwind v4 canonical class names: `wrap-break-word` not `break-words`,
`accent-primary` not `accent-[var(--primary)]`, `z-60` not `z-[60]`.
Every color used in a template must resolve through `@theme inline`.
## Electrobun
- **Window `close` is not cancellable** (response type `{}`; only the
app-level `before-quit` supports `event.response = {allow:false}`). All
unsaved-state guards must either intercept app-controlled close paths
(⌘W, buttons) or survive the close (editor draft mirroring).
- **One rpc instance per window** — BrowserView binding steals the rpc's
transport; a shared instance silently sends to the wrong webview.
- **RPC before socket open is silently lost.** Everything gates on the
socket-open promise (RpcService `ready`).
- The emitter has no `off()`. Window event closures must not capture records
you want garbage collected.
- `electrobun build` defaults to the **dev** channel; release builds need
`--env=stable`. The stable app name differs from the dev one
(`miniSCP` vs `miniSCP-dev`), including the app-data dir implications when
testing.
- Tray: never call `setImage` after construction on macOS — the template
treatment is lost and the icon renders black on dark menu bars.
- `ApplicationMenu` is macOS-only in our usage; accelerators on Windows are
single-character only. ContextMenu exists on macOS+Windows, not Linux.
- **Window-open flash prevention is three-layer** — remove any one and the
white/inverted blink returns: (1) windows are created `hidden: true` and
revealed by `showWhenReady` on the webview's first `dom-ready` (800 ms
fallback), (2) the bun preload bakes the persisted `data-theme`/tone/accent
attributes before first paint (`buildPreload`), (3) `ui/src/index.html`
carries an inline `<style>` with the html background per theme — its oklch
values MUST stay in sync with the `--background` tokens in styles.css.
- Dev vs prod URL: `getMainViewUrl()` resolves the ng-serve dev server only
when `DEV_SERVER_URL` is set AND the updater channel is `dev` AND the
server answers a HEAD request; secondary windows must reuse the resolved
URL, never hardcode `views://`.
- Upstream Bun panic (`FFI_Callback_threadsafe_call` → `web_worker.spin`):
rare segfault under long sessions; upstream electrobun×Bun issue, restart
recovers, nothing app-side to fix.
## Domain logic
- **sessionId ≠ filesystem identity.** Two panels on the same server are two
SSH sessions. Every same-file/nested-path guard compares `fsKey`
(`resolvedIP:port` / `"local"`); comparing sessionId caused a
truncate-to-zero data-loss bug. When fsKeys differ but paths collide, the
probe-file check unmasks aliased hosts. Never "simplify" this back.
- `createWriteStream` truncates BEFORE the source is read — that's why
self-copy is destructive, and why guards must run before any stream opens.
- The synthetic `'..'` row: type `'dir'`, must be excluded from selection,
targets(), filtering match-count, kind/rights/owner display, and drag
sources. Any new row-level feature must decide what `'..'` does.
- `Semaphore.wake()` must reserve slots synchronously; waking waiters that
increment asynchronously loses budget under concurrent release.
- Settings: the backend spread-merges (`{...DEFAULT_SETTINGS, ...data}`) so
new keys auto-default, but the UI SettingsService reads field-by-field —
a new setting silently stays at default until wired in all five spots.
- The editor draft mirror sends full content per tick (2 MB cap upstream);
don't shrink the 400 ms debounce.
- `panel.touched` gates localDir auto-navigation; `connectToken` guards
against a slow connect resolving into a panel the user already reused.
## Build / tooling
- Angular CLI rejects Bun's Node-compat version — `scripts/node-version-shim.ts`
is preloaded via `bunfig.toml` at the root AND in `ui/`. Removing either
breaks `ng`.
- ssh2's optional native deps must stay `external: ["cpu-features", "*.node"]`
in `electrobun.config.ts` — bundling them breaks the build; ssh2 falls back
to pure JS at runtime.
- `bun run --cwd ui build` (flag order matters; `bun --cwd ui run build` does
not do what you want).
- `version.gen.ts` is gitignored and regenerated by postinstall + every build
script; a fresh checkout fails `tsc` until `bun install` (or any script)
has run once. Never commit it — it would bump the commit count it records.
- Icon pipeline is `scripts/gen-icons.ts` (resvg) — regenerate after touching
`assets/logo.svg` or `assets/tray/tray-glyph.svg`; the .ico and tray PNGs
are build inputs, not build outputs.