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Comparison: Stream-Oriented Rendering

Most terminal UI stacks render by emitting a byte stream.

The terminal emulator interprets that stream and mutates its internal state. This works until you need correctness guarantees under mixed-width Unicode, partial redraw, or deterministic replay.

termgrid-core follows a different model: structured state transitions on an explicit grid.

Stream Model

Properties:

  • Output stream is authoritative
  • Emulator resolves layout and wrap behavior
  • State reconstruction requires replay of the stream
  • Behavior varies between emulators and browser terminals

Common failure modes:

  • Wide glyph drift
  • Wrap inconsistencies
  • Backend-specific quirks
  • Non-deterministic output under partial redraw

Grid Model

Properties:

  • Grid state is authoritative
  • Layout is resolved before emission
  • State transitions are deterministic
  • Damage is explicit

Consequences:

  • Identical input yields identical grid state
  • Backends can target terminals, xterm.js, or file formats with consistent output
  • Snapshot testing is straightforward
  • Replay is independent of emulator behavior

Architectural Maturity Signal

Stream rendering treats UI as side-effect. Grid rendering treats UI as a state machine.

That shift enables:

  • Canonical serialization
  • Portable projections
  • Bounded mutation cost
  • Explicit correctness invariants