Command Adapter Coordinate Mapping & Buffer Swaps

HostCommandAdapter maps semantic parser calls to public core methods. The parser normalizes wire parameters; core resolves geometry, origin mode, clipping, and state transitions. The adapter does not parse escape sequences or implement grid physics.

1. Coordinate Normalization

There is no single conversion for every command:

For example, CSI 2;5 H arrives as (row = 1, col = 4) and is passed directly to core. CSI 2;5 r arrives as (top = 1, bottom = 4) and becomes the core margin call (top = 2, bottom = 5). Core applies origin-mode semantics and validates or clamps geometry according to each operation's contract.

See the parser TerminalCommandSink and core contract for parameter-level rules.

2. Screen Buffer Toggling Modes

The adapter delegates screen transitions to core. See the screen-mode table for modes 47, 1047, 1048, and 1049.

Logical column mode (?3) is separate from physical window manipulation. The adapter calls resizeForColumnMode before executeDeccolm, then columnModeChanged after it succeeds. A direct embedder must synchronize its transport in the first hook; a failure must occur before destructive core changes. The second hook can schedule a host window adjustment. Neither hook should wait for UI work or reenter mutation.

3. Soft and Hard Resets

Soft Reset (DECSTR / CSI ! p)

softReset delegates to core and clears the active hyperlink metadata. Visible content, history, dimensions, and active-screen selection remain intact. Retained hyperlink registry entries still resolve. Core owns the detailed mode, pen, margin, wrap, and saved-cursor reset rules.

Hard Reset (RIS / ESC c)

resetTerminal delegates to core, clears active hyperlink metadata and both registry indexes, and emits hyperlinksCleared if the registry was nonempty. It also emits paletteChanged if core's effective palette changed. Numeric hyperlink IDs are never recycled.

RIS returns to primary and clears its content/history. Retained alternate cells can remain reachable through mode 47; their old hyperlink IDs are unresolved. Do not treat hard reset as a new adapter identity lifetime. See the registry lifetime contract and core reset contract.

Response and host-action boundaries

Core-generated replies are queued in its response channel, then drained by session or a direct embedder. HostEventSink carries metadata and action requests rather than writing transport bytes or performing platform work.

terminalResponsePolicy gates status, device, mode, keyboard, window, rectangular-checksum, DECRQSS, and XTGETTCAP replies, including supported failure replies and subscribed color-scheme/resize reports. Adapter construction and policy replacement publish the automatic-report permission to core without changing subscriptions or emitting callbacks. OSC color writes, queries, and resets and color-stack push/pop are independently gated by palettePolicy. Denied stack operations neither save nor consume an entry. OSC 21 additionally requires terminal-response permission for all replies, including unknown-key replies; its permitted mutations still apply when replies are denied. OSC 52 reads require a valid selector, clipboard-read permission, and terminal response permission; a valid denied read can still be admitted for an empty failure reply when response permission allows it. Response denial suppresses that path too.

Host theme changes use setThemePalette and can enqueue subscribed color-scheme reports even when the light/dark preference stays the same. Application OSC color changes and resets only publish effective paletteChanged metadata; they do not trigger color-scheme reports. A direct embedder must drain theme-change reports just as it drains parser-generated replies. See the protocol contract.

Permissions do not enlarge protocol allowlists. Unsupported selectors retain their protocol-defined failure or silence behavior. Detailed support status belongs in the feature map and gap map.