miniSCP/docs/gotchas.md

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.showContextMenu is a silent no-op on Linux (electrobun's own dist/api/bun/proc/linux.md says so; the app also prints "Application menus are not supported on Linux" at boot). Because the UI suppresses the webview's own right-click menu, that left EVERY panel context menu dead on Linux — no error, nothing happens. The menu is plain HTML now (ui/src/app/context-menu.ts) on every platform; don't reintroduce the native one for "nativeness" on mac/win without keeping a Linux path.

Linux

• ERR_DLOPEN_FAILED on bun run start means a missing system library, not broken app code. libNativeWrapper.so links libayatana-appindicator3.so.1 hard (for the tray), so the app cannot start at all without it — even though the tray is a minor feature. Diagnose with ldd build/dev-linux-x64/*/bin/libNativeWrapper.so | grep 'not found'; the libasar.so => not found line in that output is a red herring (it ships beside the wrapper and resolves at load). Install list per distro is in platform-notes.md.
• Benign startup noise on Linux — all non-fatal, the app runs normally: X11 Error: GLXBadWindow (code 170), Failed to create GBM buffer of size WxH: Invalid argument (compositor/GLX chatter from the GTK webview), and libayatana-appindicator is deprecated. Please use libayatana-appindicator-glib (upstream electrobun's choice, not ours).
• 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.

i18n

• Translations live in src/shared/i18n/*.ts (TS, not JSON) — deliberate: it sidesteps resolveJsonModule differences between the Angular esbuild and Bun builds and gives full typing. en.ts is the source of truth; other locales are partial and fall back to English then the raw key.
• i18n.t() is reactive because it reads the locale signal — that's what makes live language switching work with no pipe. If you cache a translated string in a plain field it WON'T update on switch; call t() in the template (or in a signal-reading getter) instead. Same for i18n.date()/size().
• Dictionary values are TS string literals: French/other apostrophes break single-quoted entries ('…c'est…'). Use double quotes for any value containing an apostrophe. Plurals are { one, other } maps (not ICU strings); zh/ja supply only other.
• Native menus can't use the Angular service — menu.ts goes through backend i18n.ts, and the app menu must be rebuilt when the locale changes (wired in index.ts settingsChanged), or it keeps the old language. The context menu no longer has this problem: it is Angular now and reads I18nService directly.
• eu/zh/ja are AI drafts pending native review (see the i18n README).
• Silent auto-refresh must snapshot sessionId+cwd and discard a mismatched result. A normal refresh() is masked by busy (input blocked), but the silent variant (poll/watch) runs while the user can navigate — without the guard, a poll that started in dir A resolves and stamps A's listing over the dir B the user just opened. It also never calls scrollCursorIntoView (scroll must stay put) and returns early if busy() or already refreshing.

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.