invalid geometry {path}: {e} (expected a JSON array of NodeG

Error message

invalid geometry {path}: {e} (expected a JSON array of NodeGeometry records)

What it means

The geometry file was read but its JSON did not deserialize into Vec<NodeGeometry> — the message spells out the expected shape ('a JSON array of NodeGeometry records'). Causes: a JSON object instead of a top-level array, missing or renamed NodeGeometry fields, wrong types, or malformed JSON.

Source

Thrown at v2/crates/wifi-densepose-cli/src/room.rs:254

/// Execute `train-room`.
///
/// If the enrollment session carries a transceiver-geometry snapshot (recorded
/// at enroll time or supplied here via `--geometry`), it is threaded into the
/// bank (ADR-152 §2.1.1); a geometry-free enrollment still trains a valid bank.
pub async fn train_room(args: TrainRoomArgs) -> Result<()> {
    let raw = std::fs::read_to_string(&args.enrollment)
        .map_err(|e| anyhow::anyhow!("cannot read {}: {e} — run `enroll` first", args.enrollment))?;
    let mut data: EnrollmentData =
        serde_json::from_str(&raw).map_err(|e| anyhow::anyhow!("invalid enrollment: {e}"))?;
    if data.anchors.is_empty() {
        bail!("no accepted anchors in {} — re-run enroll", args.enrollment);
    }

    if let Some(path) = &args.geometry {
        let graw = std::fs::read_to_string(path)
            .map_err(|e| anyhow::anyhow!("cannot read geometry {path}: {e}"))?;
        let geometry: Vec<NodeGeometry> = serde_json::from_str(&graw).map_err(|e| {
            anyhow::anyhow!("invalid geometry {path}: {e} (expected a JSON array of NodeGeometry records)")
        })?;
        data.session.record_geometry(geometry, now_unix());
    }

    let mut bank = SpecialistBank::train(&data.room_id, &data.baseline_id, &data.anchors, now_unix())
        .map_err(|e| anyhow::anyhow!("training failed: {e}"))?;
    match data.session.geometry() {
        Some(g) if !g.is_empty() => {
            bank = bank.with_geometry(g.to_vec());
            eprintln!(
                "[train-room] geometry: {} node(s) snapshotted into the bank (ADR-152 §2.1.1)",
                bank.geometry.len()
            );
        }
        _ => eprintln!(
            "[train-room] no transceiver geometry recorded — bank will not support geometry conditioning (ADR-152 §2.1.2)"
        ),
    }

View on GitHub (pinned to 4685618388)

Solutions

Wrap records in a top-level array and match NodeGeometry field names exactly as the struct's serde attributes define them
Verify with a quick deserialization probe (serde_json::from_str::<Vec<NodeGeometry>>) before invoking the CLI
Write a converter for genuinely different survey formats instead of ad-hoc edits
Omit --geometry to proceed without geometry conditioning

Example fix

// before
{ "node_id": "n1", "position_m": [1.0, 2.0] }

// after
[ { "node_id": "n1", "position_m": [1.0, 2.0] }, { "node_id": "n2", "position_m": [3.5, 0.5] } ]

Defensive patterns

Strategy: validation

Validate before calling

fn geometry_shape_ok(raw: &str) -> bool {
    serde_json::from_str::<Vec<NodeGeometry>>(raw).is_ok()
}

Type guard

fn as_geometry(raw: &str) -> Option<Vec<NodeGeometry>> {
    serde_json::from_str(raw).ok()
}

Prevention

Generate geometry files with the same serde structs that consume them
Validate geometry JSON in CI for every surveyed room snapshot
Remember the top level must be an array, not a single object

When it happens

Trigger: Passing a single object instead of an array; exporting geometry from survey tooling whose field names differ from NodeGeometry's serde schema; truncated files; passing the enrollment JSON as --geometry.

Common situations: Hand-authored geometry from site surveys; field-name drift (node identifiers, position keys) between producer tools and the NodeGeometry struct.

Related errors

AI-assisted analysis of ruvnet/RuView@4685618388 (2026-08-16). Data as JSON: /api/errors/40d1e8c58549b1ec. Report an issue: GitHub.