/**
 * Capability constants — PROTOCOL §7 / §9.1 (saga vr7kgx.6).
 *
 * A small L1 surface for the secret-free feature strings a server advertises. Servers
 * emit these in `hello.capabilities` (transport-scoped) and, for an attached runtime, in
 * the daemon-authored `sync.capabilities` (projected from the child runtime's own hello).
 * Clients must NOT infer support from the protocol version or probe unsupported commands
 * (§7) — they gate controls on the presence of these strings.
 *
 * Kept as plain `const` strings (not a closed enum) so extension/transport capabilities can
 * be advertised additively without touching this module; the typed constants here are the
 * ones the reference servers + browser controls agree on.
 */

/** Live `message_delta` streaming is available (T1–T3). */
export const CAP_STREAMING_DELTAS = 'streaming-deltas';

/** `list_models` returns a secret-free model catalog + active selection. */
export const CAP_MODEL_CATALOG = 'model-catalog';

/** `set_model` queues a catalog selection for the next provider call. */
export const CAP_MODEL_SWITCH = 'model-switch';

/** `list_reasoning_levels` returns the active model's reasoning effort catalog (saga p7m8jp.3). */
export const CAP_REASONING_CATALOG = 'reasoning-catalog';

/** `set_reasoning_level` changes the active model's reasoning effort (saga p7m8jp.3). */
export const CAP_REASONING_SWITCH = 'reasoning-switch';

/** `list_modes` returns a secret-free mode catalog + active mode. */
export const CAP_MODE_CATALOG = 'mode-catalog';

/** `set_mode` switches the active mode. */
export const CAP_MODE_SWITCH = 'mode-switch';

/**
 * The canonical v0.1 capability strings the reference runtime advertises. Transports
 * project a subset: the daemon's top-level `hello` is transport-scoped
 * (`streaming-deltas`/`websocket`), while an attached runtime's `sync.capabilities` is the
 * child runtime's exact set (mode controls are mandatory; model controls are conditional on
 * a `ModelController`).
 */
export const KNOWN_CAPABILITIES = [
  CAP_STREAMING_DELTAS,
  CAP_MODEL_CATALOG,
  CAP_MODEL_SWITCH,
  CAP_REASONING_CATALOG,
  CAP_REASONING_SWITCH,
  CAP_MODE_CATALOG,
  CAP_MODE_SWITCH,
] as const;

/** Whether a capability string is one of the known v0.1 features. Unknown strings are
 *  retained for diagnostics but grant no behavior (§7 — clients must not infer). */
export function isKnownCapability(cap: string): boolean {
  return (KNOWN_CAPABILITIES as readonly string[]).includes(cap);
}