meshtastic_firmware/test/fixtures/nodedb/README.md

Fake NodeDB Fixtures

Deterministic JSONL seed files for the v25 meshtastic_NodeDatabase format plus tooling that compiles them to binary .proto files and pushes them onto a device for testing.

Centered on Truth or Consequences, NM (33.1284°N, 107.2528°W) with a 60 km spread - change via --centroid and --spread-km if you want a different geography.

Pipeline

   bin/gen-fake-nodedb-seed.py
              ↓  (single Random(seed); no wall-clock dependence)
   test/fixtures/nodedb/seed_v25_<N>.jsonl   ← committed, hand-editable
              ↓
   bin/seed-json-to-proto.py
              ↓  (resolves *_offset_sec → now-relative epochs at compile time)
   build/fixtures/nodedb/nodes_v25_<N>.proto  ← .gitignored, fresh timestamps
              ↓
   - Portduino: cp to ~/.portduino/<config>/prefs/nodes.proto
   - Hardware: XModem upload via the meshtastic-mcp push_fake_nodedb tool

What's committed

File	Size	Purpose
seed_v25_0250.jsonl	~200 KB	Matches ESP32-S3 high-flash MAX_NUM_NODES cap
seed_v25_0500.jsonl	~400 KB	Stress between caps
seed_v25_1000.jsonl	~800 KB	Large mesh stress
seed_v25_2000.jsonl	~1.6 MB	Truncation/eviction stress (exceeds every platform cap)

Determinism contract

Structural fields are deterministic given a fixed --seed: NodeNum, long_name, short_name, hw_model, role, public_key, snr, channel, hops_away, next_hop, bitfield flags, latitude/longitude/altitude, all DeviceMetrics/EnvironmentMetrics/StatusMessage values.

Timestamps are intentionally non-deterministic at compile time. The JSONL stores *_offset_sec (seconds before "now"); the compile step subtracts these from current wall clock so the loaded NodeDB shows fresh "recently heard" peers regardless of when the fixture was generated. Pass --now-epoch T to the compile step to pin it for byte-identical CI artifacts.

Active-board allow-list

hw_model values are restricted to the intersection of:

1. Variants with custom_meshtastic_support_level = 1 in variants/*/*/platformio.ini
2. Values present in the HardwareModel enum in mesh.proto

This excludes legacy/deprecated boards (Heltec V1-V2, TLORA V1-V2, classic TBEAM (4) and TBEAM_V0P7 (6), Nano G1, Station G1/G2, etc.) and fuzzer-only sentinels (PORTDUINO, ANDROID_SIM, DIY_V1, LORA_RELAY_V1, etc.).

Refresh the allow-list in bin/gen-fake-nodedb-seed.py:HW_MODEL_WEIGHTS when boards graduate to tier-1 (or retire). One-liner to print the current intersection:

for f in $(find variants -name 'platformio.ini' | xargs grep -lE 'custom_meshtastic_support_level = 1'); do
    grep custom_meshtastic_hw_model_slug "$f" | awk -F= '{print $2}' | tr -d ' '
done | sort -u | comm -12 - <(
    bin/_generated/meshtastic_v25/__init__.py >/dev/null 2>&1 || ./bin/regen-py-protos.sh >&2
    python3 -c "import sys; sys.path.insert(0,'bin/_generated'); \
        from meshtastic_v25.mesh_pb2 import HardwareModel; \
        print('\n'.join(HardwareModel.keys()))" | sort
)

Role allow-list

role is drawn from non-deprecated Config.DeviceConfig.Role values:

• Excluded: ROUTER_CLIENT (deprecated v2.3.15), REPEATER (deprecated v2.7.11)
• Active: CLIENT, CLIENT_MUTE, ROUTER, TRACKER, SENSOR, TAK, CLIENT_HIDDEN, LOST_AND_FOUND, TAK_TRACKER, ROUTER_LATE, CLIENT_BASE

Quickstart

Regenerate fixtures with fresh timestamps

./bin/regen-fake-nodedbs.sh

This recompiles all four .proto outputs into build/fixtures/nodedb/ from the committed JSONL seeds, using current wall clock for timestamps. Re-run whenever you want "recent-looking" cached state on a freshly-booted device.

Bump the seed (regenerate JSONL structure)

REGEN_SEEDS=yes ./bin/regen-fake-nodedbs.sh

This overwrites the committed JSONL files. Commit the result.

Hand-edit a specific scenario

# Find the node you want to tweak, edit the line in place.
$EDITOR test/fixtures/nodedb/seed_v25_0250.jsonl

# Recompile and push.
./bin/regen-fake-nodedbs.sh

Each line of the JSONL is one node + metadata as the first line. Field schema documented inline in bin/gen-fake-nodedb-seed.py. To override a specific timestamp, replace the last_heard_offset_sec field with last_heard (an absolute epoch); the compile step honors absolute values.

Load onto Portduino (native macOS / linux)

cp build/fixtures/nodedb/nodes_v25_1000.proto ~/.portduino/default/prefs/nodes.proto
# Run the native binary; loadFromDisk picks it up at boot.

Push to USB-attached hardware via meshtastic-mcp

# From within the meshtastic-mcp tool surface
# (https://github.com/meshtastic/meshtastic-mcp):
push_fake_nodedb(
    size=500,
    target="hardware",
    port="/dev/cu.usbmodem21301",  # discover via list_devices
    confirm=True,                  # gates the destructive write + reboot
)

Streams the proto over XModem to /prefs/nodes.proto, then issues a 1-second reboot so loadFromDisk picks it up on next boot. CRC16-CCITT-validated chunks; retries each chunk up to 5× on NAK before aborting with CAN.

Schema reference

See bin/gen-fake-nodedb-seed.py for the JSONL field reference. Key points:

• num is a hex string ("0xa1b2c3d4")
• public_key_hex is 64 hex chars (32 bytes), empty for keyless nodes
• hw_model and role are enum names; the compile step resolves them via HardwareModel.Value(name) / Config.DeviceConfig.Role.Value(name)
• bitfield is a struct of named booleans; the compile step packs them per the bit positions in src/mesh/NodeDB.h:467-484
• position / telemetry / environment / status are nullable; coverage ratios at seed time decide which nodes get which
• latitude / longitude are floats in degrees (compiled to latitude_i = int(lat * 1e7) matching meshtastic_PositionLite)