feat(sim-control): add fail-closed intent parser for frequency-driven sim setup

Roadmap item "frequency-sim-control": pilot speaks a self-service
sim setup command on frequency ("set me up for an approach from 5000
ft to EDDF 07R", "change my altitude to 8000"). Rule-based, not an
LLM call per transmission — a misparsed command changes the user's
real sim state, and it must never be confused with real ATC
phraseology routed through sttMatch.ts.

parseSimControl() gates on explicit self-service anchors first
("set me up", "put me", "change/set my <param>"); anything without
one of those anchors returns no_intent, so regular readbacks and
clearances can never be misrouted. Matched intents still refuse on
any ambiguous slot (missing unit, out-of-range, invalid runway) with
a typed reason instead of guessing.

Parameter vocabulary follows NormalizedTelemetry (altitude_ft,
ias_kts, heading_deg) since the command travels toward the bridge/sim,
not the decision engine's DecisionNodeAutoTrigger vocabulary.

Design doc covers the still-missing server→bridge write channel
(piggyback on the existing telemetry POST response) — not
implemented yet, this commit is the parser only.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

shared/utils/simControl.ts

@@ -0,0 +1,167 @@
+// Frequency-driven simulator control (roadmap key `frequency-sim-control`).
+//
+// Parses free-form SIM SETUP commands the pilot speaks on frequency ("set me
+// up for an approach from 5000 ft to EDDF 07R", "change my altitude to 8000")
+// into structured commands for the bridge. These are meta commands from the
+// user to their OWN simulator instance — deliberately a different grammar from
+// ICAO readback phraseology (which runs through sttMatch.ts) so an ordinary
+// ATC readback can never be mistaken for a sim command.
+//
+// Fail-closed by design: anything ambiguous returns { matched: false } with a
+// reason instead of a best-effort guess — a misparsed command changes the
+// user's real sim state. Parameter names follow the NormalizedTelemetry
+// convention (useRadioBackend.ts): the command travels toward the bridge/sim,
+// so it speaks the sim-side vocabulary (altitude_ft, ias_kts, heading_deg).
+
+import { denormalizeSpokenAtc, normalizeForMatch } from './sttMatch'
+
+export type SimControlCommand =
+  | { type: 'set_altitude'; altitude_ft: number }
+  | { type: 'set_heading'; heading_deg: number }
+  | { type: 'set_speed'; ias_kts: number }
+  | {
+      type: 'setup_approach'
+      /** Uppercase 4-letter ICAO ("EDDF"). Existence is the caller's check. */
+      airport_icao: string
+      /** "07R", "26L", "23" — zero-padded number 01–36 + optional L/R/C. */
+      runway: string
+      altitude_ft?: number
+      final_distance_nm?: number
+    }
+
+export type SimControlNoMatchReason =
+  | 'no_intent'
+  | 'missing_value'
+  | 'missing_unit'
+  | 'out_of_range'
+  | 'invalid_runway'
+  | 'missing_runway'
+  | 'missing_airport'
+
+export type SimControlParseResult =
+  | { matched: true; command: SimControlCommand; text: string }
+  | { matched: false; reason: SimControlNoMatchReason; text: string }
+
+/** Hard value ranges; anything outside is a refusal, never a clamp. */
+export const SIM_CONTROL_LIMITS = {
+  altitude_ft: { min: 0, max: 45000 },
+  heading_deg: { min: 1, max: 360 },
+  ias_kts: { min: 60, max: 400 },
+  final_distance_nm: { min: 1, max: 30 },
+} as const
+
+// 4-letter English words that can follow "to/at/for" in an approach phrase
+// and must never be mistaken for an ICAO code.
+const ICAO_STOPWORDS = new Set([
+  'left', 'right', 'feet', 'final', 'mile', 'nautical', 'from', 'with', 'land',
+])
+
+function noMatch(reason: SimControlNoMatchReason, text: string): SimControlParseResult {
+  return { matched: false, reason, text }
+}
+
+function inRange(value: number, limit: { min: number; max: number }): boolean {
+  return value >= limit.min && value <= limit.max
+}
+
+/** "flight level 100" / "fl100" → feet, or null when no FL phrase is present. */
+function flightLevelFeet(fragment: string): number | null {
+  const fl = fragment.match(/\b(?:flight level|fl) ?(\d{1,3})\b/)
+  return fl ? Number(fl[1]) * 100 : null
+}
+
+function parseApproach(text: string): SimControlParseResult {
+  // Runway: keyword form ("runway 26 l" → "runway 26l" after denormalize) or a
+  // bare suffixed token ("25r"). A bare number WITHOUT suffix is only accepted
+  // behind the "runway" keyword — a lone "25" in the sentence is too ambiguous.
+  const keyword = text.match(/\brunway (\d{1,2}) ?([lrc])?\b/)
+  const bareToken = text.match(/(?:^|\s)(\d{2})([lrc])(?:\s|$)/)
+  const rwNumRaw = keyword?.[1] ?? bareToken?.[1]
+  const rwSuffix = (keyword ? keyword[2] : bareToken?.[2]) ?? ''
+  if (!rwNumRaw) return noMatch('missing_runway', text)
+  const rwNum = Number(rwNumRaw)
+  if (rwNum < 1 || rwNum > 36) return noMatch('invalid_runway', text)
+  const runway = `${rwNumRaw.padStart(2, '0')}${rwSuffix.toUpperCase()}`
+
+  const airport = text.match(/\b(?:to|at|for|into) ([a-z]{4})\b/)
+  if (!airport || ICAO_STOPWORDS.has(airport[1]!)) return noMatch('missing_airport', text)
+  const airport_icao = airport[1]!.toUpperCase()
+
+  // Altitude is optional, but WHEN a "from <number>" is present it must carry
+  // an explicit unit (feet/ft) or be a flight level — a bare "from 5000" is
+  // ambiguous and refused rather than guessed.
+  let altitude_ft: number | undefined
+  const fromFl = text.match(/\bfrom (?:flight level|fl) ?(\d{1,3})\b/)
+  const fromFt = text.match(/\bfrom (\d{3,5}) ?(?:feet|ft)\b/)
+  if (fromFl) altitude_ft = Number(fromFl[1]) * 100
+  else if (fromFt) altitude_ft = Number(fromFt[1])
+  else if (/\bfrom \d/.test(text)) return noMatch('missing_unit', text)
+  if (altitude_ft !== undefined && !inRange(altitude_ft, SIM_CONTROL_LIMITS.altitude_ft)) {
+    return noMatch('out_of_range', text)
+  }
+
+  let final_distance_nm: number | undefined
+  const dist = text.match(/\b(\d{1,2}) ?(?:miles?|nm|nautical miles?) final\b/)
+  if (dist) {
+    final_distance_nm = Number(dist[1])
+    if (!inRange(final_distance_nm, SIM_CONTROL_LIMITS.final_distance_nm)) {
+      return noMatch('out_of_range', text)
+    }
+  }
+
+  const command: SimControlCommand = { type: 'setup_approach', airport_icao, runway }
+  if (altitude_ft !== undefined) command.altitude_ft = altitude_ft
+  if (final_distance_nm !== undefined) command.final_distance_nm = final_distance_nm
+  return { matched: true, command, text }
+}
+
+function parseParameter(
+  parameter: 'altitude' | 'heading' | 'speed',
+  rest: string,
+  text: string,
+): SimControlParseResult {
+  if (parameter === 'altitude') {
+    // "altitude" names the unit context, so a bare number is unambiguous here
+    // (this is the literal roadmap wording "change my altitude to 8000").
+    const fl = flightLevelFeet(rest)
+    const num = fl ?? Number(rest.match(/\b(\d{1,6})\b/)?.[1] ?? NaN)
+    if (!Number.isFinite(num)) return noMatch('missing_value', text)
+    if (!inRange(num, SIM_CONTROL_LIMITS.altitude_ft)) return noMatch('out_of_range', text)
+    return { matched: true, command: { type: 'set_altitude', altitude_ft: num }, text }
+  }
+  if (parameter === 'heading') {
+    const num = Number(rest.match(/\b(\d{1,3})\b/)?.[1] ?? NaN)
+    if (!Number.isFinite(num)) return noMatch('missing_value', text)
+    if (!inRange(num, SIM_CONTROL_LIMITS.heading_deg)) return noMatch('out_of_range', text)
+    return { matched: true, command: { type: 'set_heading', heading_deg: num }, text }
+  }
+  const num = Number(rest.match(/\b(\d{2,3})\b/)?.[1] ?? NaN)
+  if (!Number.isFinite(num)) return noMatch('missing_value', text)
+  if (!inRange(num, SIM_CONTROL_LIMITS.ias_kts)) return noMatch('out_of_range', text)
+  return { matched: true, command: { type: 'set_speed', ias_kts: num }, text }
+}
+
+/**
+ * Parse a transmission into a sim-control command, or refuse.
+ *
+ * The intent gate is intentionally narrow: only explicit self-service anchors
+ * ("set me up …", "put me …", "reposition …" for approaches; "change/set my
+ * <parameter> …" for single values) enter parsing at all. Regular phraseology
+ * ("descend to 5000 feet", "request descent …", "cleared to land …") carries
+ * none of these anchors and always returns `no_intent` — that property is the
+ * safety contract of this module and is covered by tests.
+ */
+export function parseSimControl(input: string): SimControlParseResult {
+  const text = normalizeForMatch(denormalizeSpokenAtc(input))
+  if (!text) return noMatch('no_intent', text)
+
+  const wantsApproach = /\b(?:set me up|put me|reposition(?: me)?)\b.*\b(?:approach|final)\b/.test(text)
+  if (wantsApproach) return parseApproach(text)
+
+  const parameter = text.match(/\b(?:change|set) my (altitude|heading|speed)\b(.*)$/)
+  if (parameter) {
+    return parseParameter(parameter[1] as 'altitude' | 'heading' | 'speed', parameter[2] ?? '', text)
+  }
+
+  return noMatch('no_intent', text)
+}