diff --git a/packages/hal/src/dispensers/error-codes.ts b/packages/hal/src/dispensers/error-codes.ts
new file mode 100644
index 0000000..8da360f
--- /dev/null
+++ b/packages/hal/src/dispensers/error-codes.ts
@@ -0,0 +1,60 @@
+/**
+ * Dispense error taxonomy shared by every dispenser driver (ADR-005 §7).
+ *
+ * Three fields travel with a failed dispense, mirroring the shape
+ * lamassu-server kept on cash_out_txs — `error` (human), `error_code`
+ * (the error's NAME), plus the boolean the caller computes on value:
+ *
+ *   errorCode   the family, e.g. 'F56DispenseError' — stable, machine-readable
+ *   rawCode     the driver-native code, e.g. '78 42' — for the decode table
+ *   errorClass  how the caller should route it (below)
+ *   human       what an operator will find when they open the machine
+ *
+ * errorClass decides what the state machine does next:
+ *
+ *   terminal     the transport path is compromised (jam, motor, diverter,
+ *                sensor, comm timeout). Retrying from another bay would jam
+ *                too, and re-initialising does not move a stuck note. The
+ *                machine latches cash-out off until an operator clears it.
+ *   recoverable  this bay or this note (pick failure, length/thickness
+ *                reject, bill-end). The customer-facing fault screen still
+ *                shows — they have paid — but the machine stays in service.
+ *   inventory    nothing was asked of the hardware: the request could not be
+ *                met from the bays. Not a fault; routes to the out-of-cash
+ *                screen, and nothing was charged beyond what was dispensed.
+ *
+ * No code here is borrowed from another layer's vocabulary. lamassu tagged
+ * every F56 fault with statusCode 570, which its server read as "insufficient
+ * funds" — a jam told the operator to refill a cassette that was not empty.
+ */
+
+export type DispenseErrorClass = 'terminal' | 'recoverable' | 'inventory'
+
+export interface DispenseErrorInfo {
+  errorCode: string
+  rawCode?: string
+  errorClass: DispenseErrorClass
+  human: string
+}
+
+/** An Error carrying the taxonomy. Drivers return these from `dispense()`. */
+export interface DispenseError extends Error, DispenseErrorInfo {}
+
+/** Stamp the taxonomy onto an existing Error without losing its stack. */
+export function tagDispenseError(error: Error, info: DispenseErrorInfo): DispenseError {
+  const tagged = error as DispenseError
+  tagged.name = info.errorCode
+  tagged.errorCode = info.errorCode
+  tagged.rawCode = info.rawCode
+  tagged.errorClass = info.errorClass
+  tagged.human = info.human
+  return tagged
+}
+
+export function isDispenseError(err: unknown): err is DispenseError {
+  return (
+    err instanceof Error &&
+    typeof (err as Partial<DispenseError>).errorCode === 'string' &&
+    typeof (err as Partial<DispenseError>).errorClass === 'string'
+  )
+}
diff --git a/packages/hal/src/dispensers/f56/__tests__/bills.test.ts b/packages/hal/src/dispensers/f56/__tests__/bills.test.ts
new file mode 100644
index 0000000..1ed588e
--- /dev/null
+++ b/packages/hal/src/dispensers/f56/__tests__/bills.test.ts
@@ -0,0 +1,64 @@
+/**
+ * The F56 bill table is a list of [hi, lo] accept windows in millimetres per
+ * denomination, sent to the BDU at initialise. It was carried byte for byte
+ * from lamassu with nothing over it, and a wrong GTQ window produced a
+ * production fault (5/5 notes rejected, error 82 00) for weeks. These tests
+ * are the "no value table without a test" rule from ADR-005 finding 10.
+ */
+import { describe, it, expect } from 'vitest'
+import { bills } from '../bills.js'
+
+/**
+ * Every quetzal, dollar and lempira note is 156 × 67 mm. HNL is in lamassu's
+ * 37-currency table but not (yet) in ours — include it only if present so the
+ * invariant holds the day it is added.
+ */
+const SAME_PHYSICAL_NOTE = (['USD', 'GTQ', 'HNL'] as const).filter((c) => c in bills)
+
+describe('F56 bill table', () => {
+  const currencies = Object.keys(bills)
+
+  it('has entries', () => {
+    expect(currencies.length).toBeGreaterThan(0)
+  })
+
+  it.each(currencies)('%s: every window is [hi, lo] with hi > lo and a plausible note length', (cur) => {
+    const data = bills[cur]!
+    expect(typeof data.thickness).toBe('number')
+    expect(typeof data.polymer).toBe('boolean')
+    for (const [denom, window] of Object.entries(data.lengths)) {
+      const [hi, lo] = window
+      expect(hi, `${cur} ${denom} hi`).toBeGreaterThan(lo)
+      // Real banknotes are roughly 110–180 mm long; a window outside that
+      // means a typo, not a note.
+      expect(lo, `${cur} ${denom} lo`).toBeGreaterThanOrEqual(100)
+      expect(hi, `${cur} ${denom} hi`).toBeLessThanOrEqual(190)
+      // A window narrower than ±5 rejects real notes on sensor noise; wider
+      // than ±15 stops catching offset double-picks.
+      expect(hi - lo, `${cur} ${denom} width`).toBeGreaterThanOrEqual(10)
+      expect(hi - lo, `${cur} ${denom} width`).toBeLessThanOrEqual(30)
+    }
+  })
+
+  it('GTQ, USD and HNL — physically the same 156 mm note — share one window', () => {
+    const windows = SAME_PHYSICAL_NOTE.map((cur) => {
+      const lengths = bills[cur]!.lengths
+      const all = Object.values(lengths).map(([hi, lo]) => `${hi}-${lo}`)
+      return { cur, distinct: [...new Set(all)] }
+    })
+    for (const w of windows) {
+      expect(w.distinct, `${w.cur} has one window for all denominations`).toHaveLength(1)
+    }
+    const usd = windows.find((w) => w.cur === 'USD')!.distinct[0]
+    for (const w of windows) {
+      expect(w.distinct[0], `${w.cur} matches USD (lamassu b1cc3622)`).toBe(usd)
+    }
+  })
+
+  it('the 156 mm window is 146–166 (±10)', () => {
+    const [hi, lo] = bills.USD!.lengths[20]!
+    expect(hi).toBe(166)
+    expect(lo).toBe(146)
+    expect((hi + lo) / 2).toBe(156)
+  })
+})
diff --git a/packages/hal/src/dispensers/f56/__tests__/error-codes.test.ts b/packages/hal/src/dispensers/f56/__tests__/error-codes.test.ts
new file mode 100644
index 0000000..f7d7375
--- /dev/null
+++ b/packages/hal/src/dispensers/f56/__tests__/error-codes.test.ts
@@ -0,0 +1,66 @@
+import { describe, it, expect } from 'vitest'
+import { decodeF56Error, listF56ErrorCodes, normaliseF56Code, F56_ERROR_CODE } from '../error-codes.js'
+
+describe('F56 error-code decode (ADR-005 §7)', () => {
+  it("decodes sintra's exit jam as terminal", () => {
+    const info = decodeF56Error('78 42')
+    expect(info.errorCode).toBe(F56_ERROR_CODE)
+    expect(info.rawCode).toBe('78 42')
+    expect(info.errorClass).toBe('terminal')
+    expect(info.human).toMatch(/cassette exit/i)
+  })
+
+  it("decodes the Tejo's long-bill reject as recoverable", () => {
+    const info = decodeF56Error('82 00')
+    expect(info.errorClass).toBe('recoverable')
+    expect(info.human).toMatch(/length/i)
+  })
+
+  it('decodes parameterised families by first byte', () => {
+    expect(decodeF56Error('85 03').errorClass).toBe('recoverable')
+    expect(decodeF56Error('85 03').human).toMatch(/another safe/i)
+    expect(decodeF56Error('B5 01').errorClass).toBe('terminal')
+    expect(decodeF56Error('b5 7f').errorClass).toBe('terminal')
+  })
+
+  it('fails SAFE on an unknown code: terminal, named, code preserved', () => {
+    const info = decodeF56Error('99 99')
+    expect(info.errorCode).toBe(F56_ERROR_CODE)
+    expect(info.errorClass).toBe('terminal')
+    expect(info.rawCode).toBe('99 99')
+    expect(info.human).toContain('99 99')
+  })
+
+  it('treats a missing frame (serial timeout) as terminal', () => {
+    const info = decodeF56Error(undefined)
+    expect(info.errorClass).toBe('terminal')
+    expect(info.rawCode).toBeUndefined()
+  })
+
+  it('normalises spelling variants to "XX YY"', () => {
+    expect(normaliseF56Code('7842')).toBe('78 42')
+    expect(normaliseF56Code('78-42')).toBe('78 42')
+    expect(normaliseF56Code('78 42')).toBe('78 42')
+    expect(normaliseF56Code('b5 01')).toBe('B5 01')
+    expect(decodeF56Error('7842')).toEqual(decodeF56Error('78 42'))
+  })
+
+  it('never borrows another layer\'s code (the lamassu 570 lesson)', () => {
+    for (const row of listF56ErrorCodes()) {
+      expect(row).not.toHaveProperty('statusCode')
+    }
+    expect(decodeF56Error('78 42')).not.toHaveProperty('statusCode')
+  })
+
+  it('lists every known code for the operator glossary', () => {
+    const codes = listF56ErrorCodes().map((r) => r.code)
+    expect(codes).toContain('78 42')
+    expect(codes).toContain('82 00')
+    expect(codes).toContain('85 ..')
+    expect(codes).toContain('B5 ..')
+    for (const row of listF56ErrorCodes()) {
+      expect(['terminal', 'recoverable', 'inventory']).toContain(row.errorClass)
+      expect(row.human.length).toBeGreaterThan(10)
+    }
+  })
+})
diff --git a/packages/hal/src/dispensers/f56/error-codes.ts b/packages/hal/src/dispensers/f56/error-codes.ts
new file mode 100644
index 0000000..2b6af4d
--- /dev/null
+++ b/packages/hal/src/dispensers/f56/error-codes.ts
@@ -0,0 +1,109 @@
+/**
+ * Fujitsu F53/F56 BDU error-code decode table (ADR-005 §7).
+ *
+ * The BDU answers a failed bill-count with an 0xF0 frame whose bytes 3–4 are
+ * the error code; `f56-rs232.billCount` surfaces them as `rawCode` in the
+ * form prettyHex produces, e.g. '78 42'. Neither lamassu codebase ever
+ * decoded these — both collapsed every fault into one opaque string.
+ *
+ * Built empirically and from the Fujitsu Frontech F56-BDU Error Code List
+ * (K3KD03234–K3KD03236-0001, ed. E02). Entries are keyed by the full two-byte
+ * code, or by the first byte for families where the second byte is a
+ * parameter (`85 0n` = pick from another safe n; `B5 ..` = reject-box
+ * overflow). An unknown code fails SAFE: terminal, so an unfamiliar fault
+ * latches cash-out off rather than letting the next customer pay into it.
+ *
+ * Add a row when a code occurs. Each row's `observed` is the first machine
+ * and date we saw it, so the table doubles as the incident log.
+ */
+
+import type { DispenseErrorClass, DispenseErrorInfo } from '../error-codes.js'
+
+export const F56_ERROR_CODE = 'F56DispenseError'
+
+interface F56ErrorEntry {
+  errorClass: DispenseErrorClass
+  human: string
+  /** First observed — machine, date. Empty for spec-only entries. */
+  observed?: string
+}
+
+/** Exact two-byte codes. */
+const EXACT: Record<string, F56ErrorEntry> = {
+  '78 42': {
+    errorClass: 'terminal',
+    human: 'Note stopped at the cassette exit — open the unit and clear the transport path',
+    observed: 'sintra, 2026-10-09',
+  },
+  '82 00': {
+    errorClass: 'recoverable',
+    human: 'Bill length check failed (long) — note read longer than the configured window',
+    observed: 'tejo (GTQ), 2026-09-26',
+  },
+  '83 00': {
+    errorClass: 'recoverable',
+    human: 'Bill length check failed (short)',
+  },
+  '84 00': {
+    errorClass: 'recoverable',
+    human: 'Bill thickness check failed — possible double pick or damaged note',
+  },
+  '86 00': {
+    errorClass: 'recoverable',
+    human: 'Bill spacing error — notes too close together on the transport',
+  },
+}
+
+/** Families keyed by the first byte; the second byte is a parameter. */
+const FAMILY: Record<string, F56ErrorEntry> = {
+  '85': {
+    errorClass: 'recoverable',
+    human: 'Pick from another safe — the note came from a different cassette than commanded',
+  },
+  B5: {
+    errorClass: 'terminal',
+    human: 'Reject box overflow — empty the reject tray',
+  },
+}
+
+/** Normalise '78 42', '7842', '78-42', lowercase, etc. to 'XX YY'. */
+export function normaliseF56Code(raw: string): string {
+  const hex = raw.replace(/[^0-9a-fA-F]/g, '').toUpperCase()
+  if (hex.length !== 4) return raw.trim().toUpperCase()
+  return `${hex.slice(0, 2)} ${hex.slice(2, 4)}`
+}
+
+export function decodeF56Error(rawCode: string | undefined): DispenseErrorInfo {
+  if (!rawCode) {
+    // No frame came back at all — serial timeout, port closed, framing error.
+    // The transport is in an unknown state; treat as terminal.
+    return {
+      errorCode: F56_ERROR_CODE,
+      errorClass: 'terminal',
+      human: 'Dispenser did not answer — serial timeout or framing error',
+    }
+  }
+  const code = normaliseF56Code(rawCode)
+  const exact = EXACT[code]
+  if (exact) {
+    return { errorCode: F56_ERROR_CODE, rawCode: code, errorClass: exact.errorClass, human: exact.human }
+  }
+  const family = FAMILY[code.slice(0, 2)]
+  if (family) {
+    return { errorCode: F56_ERROR_CODE, rawCode: code, errorClass: family.errorClass, human: family.human }
+  }
+  return {
+    errorCode: F56_ERROR_CODE,
+    rawCode: code,
+    errorClass: 'terminal',
+    human: `Unrecognised dispenser error ${code} — treat as a jam until decoded`,
+  }
+}
+
+/** For the operator glossary: every known code with its class and meaning. */
+export function listF56ErrorCodes(): Array<{ code: string; errorClass: DispenseErrorClass; human: string; observed?: string }> {
+  return [
+    ...Object.entries(EXACT).map(([code, e]) => ({ code, ...e })),
+    ...Object.entries(FAMILY).map(([code, e]) => ({ code: `${code} ..`, ...e })),
+  ]
+}
diff --git a/packages/hal/src/dispensers/f56/f56-rs232.ts b/packages/hal/src/dispensers/f56/f56-rs232.ts
index 24e1d60..397f4e7 100644
--- a/packages/hal/src/dispensers/f56/f56-rs232.ts
+++ b/packages/hal/src/dispensers/f56/f56-rs232.ts
@@ -134,6 +134,8 @@ export async function initialize(currency: string, denominations: number[]): Pro
 export interface BillCountResult {
   bills: Array<{ dispensed: number; rejected: number }>
   error?: Error
+  /** BDU error code from bytes 3–4 of an 0xF0 frame, e.g. '78 42'. */
+  rawCode?: string
 }
 
 export async function billCount(counts: number[]): Promise<BillCountResult> {
@@ -172,9 +174,10 @@ export async function billCount(counts: number[]): Promise<BillCountResult> {
 
   if (res[0] === 0xf0) {
     console.log('response', res)
-    const errorCode = res.subarray(3, 5)
-    response.error = new Error(`Dispensing, code: ${prettyHex(errorCode)}`)
-    console.error(`found error code: ${prettyHex(errorCode)}`)
+    const rawCode = prettyHex(res.subarray(3, 5))
+    response.rawCode = rawCode
+    response.error = new Error(`Dispensing, code: ${rawCode}`)
+    console.error(`found error code: ${rawCode}`)
   }
 
   return response
diff --git a/packages/hal/src/dispensers/f56/index.ts b/packages/hal/src/dispensers/f56/index.ts
index c64882d..52a5c03 100644
--- a/packages/hal/src/dispensers/f56/index.ts
+++ b/packages/hal/src/dispensers/f56/index.ts
@@ -8,6 +8,8 @@
  */
 
 import * as f56 from './f56-rs232.js'
+import { decodeF56Error } from './error-codes.js'
+import { tagDispenseError, type DispenseError } from '../error-codes.js'
 import type {
   BillDispenser,
   DispenserConfig,
@@ -51,23 +53,28 @@ export class F56Dispenser implements BillDispenser {
     }
   }
 
-  async dispense(notes: number[]): Promise<{ value: DispenseResult[]; error?: Error }> {
+  /**
+   * On any failure the port is closed so the next attempt re-initialises;
+   * the error is tagged with the ADR-005 taxonomy (class + decoded meaning)
+   * so the caller can route it. No statusCode: lamassu's 570 meant
+   * "insufficient funds" to its server and sent operators to refill full
+   * cassettes after jams.
+   */
+  async dispense(notes: number[]): Promise<{ value: DispenseResult[]; error?: DispenseError }> {
     try {
-      const { bills, error } = await f56.billCount(notes)
+      const { bills, error, rawCode } = await f56.billCount(notes)
 
       if (error) {
         await this.close()
-        ;(error as Error & { name: string; statusCode: number }).name = 'F56DispenseError'
-        ;(error as Error & { statusCode: number }).statusCode = 570
+        return { value: bills, error: tagDispenseError(error, decodeF56Error(rawCode)) }
       }
 
-      return { value: bills, error }
+      return { value: bills }
     } catch (err) {
       await this.close()
-      const error = err as Error
-      ;(error as Error & { name: string; statusCode: number }).name = 'F56DispenseError'
-      ;(error as Error & { statusCode: number }).statusCode = 570
-      return { value: [], error }
+      const error = err instanceof Error ? err : new Error(String(err))
+      // No frame: serial timeout / framing. decodeF56Error(undefined) → terminal.
+      return { value: [], error: tagDispenseError(error, decodeF56Error(undefined)) }
     }
   }
 
diff --git a/packages/hal/src/dispensers/puloon/index.ts b/packages/hal/src/dispensers/puloon/index.ts
index f065fd4..034c3ce 100644
--- a/packages/hal/src/dispensers/puloon/index.ts
+++ b/packages/hal/src/dispensers/puloon/index.ts
@@ -14,6 +14,7 @@ import type {
   DispenserInitData,
   DispenseResult,
 } from '../../types.js'
+import { tagDispenseError, type DispenseError } from '../error-codes.js'
 
 export class PuloonDispenser implements BillDispenser {
   public type: string = 'Puloon'
@@ -46,16 +47,26 @@ export class PuloonDispenser implements BillDispenser {
     }
   }
 
-  async dispense(notes: number[]): Promise<{ value: DispenseResult[]; error?: Error }> {
+  async dispense(notes: number[]): Promise<{ value: DispenseResult[]; error?: DispenseError }> {
     const { bills, error } = await this.device.dispense(notes)
 
     if (error) {
       await this.close()
-      error.name = 'PuloonDispenseError'
       console.log('PULOON | dispense error', error)
+      // No decode table for the LCDM yet: every fault is terminal until one
+      // exists, so an unknown Puloon error latches cash-out off (ADR-005 §7).
+      return {
+        value: bills,
+        error: tagDispenseError(error, {
+          errorCode: 'PuloonDispenseError',
+          rawCode: (error as Error & { code?: string }).code,
+          errorClass: 'terminal',
+          human: `Puloon dispense error: ${error.message}`,
+        }),
+      }
     }
 
-    return { value: bills, error }
+    return { value: bills }
   }
 
   async close(): Promise<void> {
diff --git a/packages/hal/src/index.ts b/packages/hal/src/index.ts
index dca91f5..46a76ed 100644
--- a/packages/hal/src/index.ts
+++ b/packages/hal/src/index.ts
@@ -57,5 +57,20 @@ export type {
   DispenserFactory,
 } from './types.js'
 
+// Dispense error taxonomy (ADR-005 §7)
+export {
+  tagDispenseError,
+  isDispenseError,
+  type DispenseError,
+  type DispenseErrorClass,
+  type DispenseErrorInfo,
+} from './dispensers/error-codes.js'
+export {
+  decodeF56Error,
+  listF56ErrorCodes,
+  normaliseF56Code,
+  F56_ERROR_CODE,
+} from './dispensers/f56/error-codes.js'
+
 // Utilities
 export { compute as computeCrc } from './utils/crc.js'
diff --git a/packages/hal/src/types.ts b/packages/hal/src/types.ts
index bf0615f..96c21dc 100644
--- a/packages/hal/src/types.ts
+++ b/packages/hal/src/types.ts
@@ -1,3 +1,5 @@
+import type { DispenseError } from './dispensers/error-codes.js'
+
 import { EventEmitter } from 'node:events'
 
 /**
@@ -176,7 +178,8 @@ export interface BillDispenser {
    */
   dispense(notes: number[]): Promise<{
     value: DispenseResult[]
-    error?: Error
+    /** Tagged with the ADR-005 taxonomy — see dispensers/error-codes.ts */
+    error?: DispenseError
   }>
 
   /**