Context

This issue tracks the ST-LIB implementation of ADJv3, as specified in the
first Communications meeting (2026-09-10). ADJv3 builds on ADJv2, with the main
conceptual change being the decoupling of messages and protections:
previously a protection was just a message of a given type; now they have
independent packet structures.

1. Numeric id for packets/orders/measurements

• Replace the textual id with a numeric identifier shared across packets,
  orders, and measurements, range [0, 8191] (uint13).
• IDs [0, 511] are reserved as special IDs (not assigned to
  packets/orders/protections).
• Keep the old textual id under a new field alias, since codegen still
  depends on it for variable naming and it's needed for logging-view
  compatibility.

2. protections decoupled from messages

Each measurement in <BOARD>_measurements.json gets an optional
protections array (max 7 entries):

{
  "type":  "<protection type>",
  "value": [number] | [number, number],
  "fault": boolean?,
  "time":  "<number><unit>?"
}

• type: one of the types declared in general_info.json →
  protectionTypes (Above, Below, Equal, NotEqual, Range).
• value: single limit, or [min, max] for Range.
• fault: default true → emitted as fault; false → warning.
• time: only for time-accumulation protections (e.g. "500ms", "3s"),
  default 0.

protectionTypes definition in general_info.json:

{
  "protectionTypes": {
    "<protection_name>": {
      "range":    boolean?,
      "text":     "<template>",
      "textTime": "<template>?"
    }
  }
}

Protection packet layout

Fixed 48-bit header (id + timestamp) followed by a value field whose
size matches the monitored measurement's type (8–64 bits):

• id (bits 0–15): numeric protection id.
• timestamp (bits 16–47): hour/min/sec (1 byte each) + 1 reserved byte. (NOT RATIFICATED YET)
• value (bits 48+): same size/encoding as the monitored measurement.

Composite id (bit-packing)

Since packets, orders, and protections share the same 16-bit id
field, the top 3 bits (pos) disambiguate:

• pos = 000: normal id (packet/order/measurement), remaining 13 bits = id.
• pos = 001–111: protections[0]–protections[6] of the measurement
  identified by the low 13 bits.

id = (pos << 13) | id_measurement

Transmitted as a single little-endian uint16.

3. message refactor

New packet layout:

• id (2 bytes, uint16): reuses message_ids from general_info.json.
  New value: 13 = panic (previously masked as fault in ST-LIB).
• timestamp (4 bytes): same short format as protections (hour/min/sec
  • 1 reserved byte).
• origin (up to 48 bytes, null-terminated string): source file path.
• message (up to 320 bytes, null-terminated string): message content.

message_ids in general_info.json:

{
"message_ids": {
"fault": 10,
"warning": 11,
"info": 12,
"panic": 13
}
}

4. Add mac field to board info

Add a mac field (board MAC address) to be used in codegen and validated by
adj-validator, to catch invalid/duplicate MACs at build time (motivated by
MAC-related issues found during H11 EHW).

Open questions (to resolve in next meeting, not blocking this issue's scope)

• Reserve a special-ID range for the BLCU.
• ADJ commit verification at TCP connection start.
• Custom keep-alive mechanism.
• Whether to keep the units module or drop it.
• Support for measurement arrays (pending Víctor's proposal).

Acceptance criteria

• id becomes numeric (uint13) across packets/orders/measurements;
  legacy textual id preserved as alias.
• protections array support in _measurements.json (max 7),
  with protectionTypes read from general_info.json.
• Protection packet encode/decode matches the layout above.
• Composite id (pos + id_measurement) encode/decode implemented.
• message packet refactored to the new layout, panic type added.
• mac field added to board info, validated by adj-validator.

See ACTA