diff --git a/Cargo.lock b/Cargo.lock
index 956a0fee..5fea573f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -802,6 +802,10 @@ version = "0.1.0"
 [[package]]
 name = "solvecraft-cli"
 version = "0.1.0"
+dependencies = [
+ "serde_json",
+ "solvecraft-engine",
+]
 
 [[package]]
 name = "solvecraft-doc"
@@ -827,6 +831,7 @@ dependencies = [
  "solvecraft-geom",
  "solvecraft-io",
  "solvecraft-kernel",
+ "solvecraft-render",
  "solvecraft-sketch",
  "thiserror 2.0.21",
 ]
diff --git a/apps/solvecraft-cli/Cargo.toml b/apps/solvecraft-cli/Cargo.toml
index bbefa761..89aaab95 100644
--- a/apps/solvecraft-cli/Cargo.toml
+++ b/apps/solvecraft-cli/Cargo.toml
@@ -1,5 +1,17 @@
 [package]
 name = "solvecraft-cli"
+description = "SolveCraft headless CLI: run command scripts, measure, export, render snapshots, replay oracle recipes"
 version.workspace = true
 edition.workspace = true
 license.workspace = true
+
+[lints]
+workspace = true
+
+[[bin]]
+name = "solvecraft-cli"
+path = "src/main.rs"
+
+[dependencies]
+solvecraft-engine = { workspace = true }
+serde_json = { workspace = true }
diff --git a/apps/solvecraft-cli/src/main.rs b/apps/solvecraft-cli/src/main.rs
index f328e4d9..86fabbaf 100644
--- a/apps/solvecraft-cli/src/main.rs
+++ b/apps/solvecraft-cli/src/main.rs
@@ -1 +1,157 @@
-fn main() {}
+//! SolveCraft headless command line.
+//!
+//! ```text
+//! solvecraft-cli run <script.json|design.solvecraft> [--out FILE]... [--save FILE] [--quiet]
+//! solvecraft-cli eval <script.json|design.solvecraft>        (alias: inspect) measurements as JSON
+//! solvecraft-cli snapshot <script|design> --out shot.png [--width W] [--height H] [--view iso|front|top|…]
+//! solvecraft-cli exec <command> [json-params]                 run one command on an empty design
+//! solvecraft-cli commands                                     the command registry as JSON
+//! solvecraft-cli recipe <recipe.json>                         translate an oracle recipe to a script
+//! solvecraft-cli oracle <case-dir>...                         replay recipes and compare with measure.json
+//! ```
+#![deny(clippy::unwrap_used, clippy::expect_used, clippy::panic, clippy::unimplemented, clippy::todo, clippy::unreachable)]
+#![forbid(unsafe_code)]
+
+mod oracle;
+mod recipe;
+
+use std::process::ExitCode;
+
+use serde_json::{Value, json};
+use solvecraft_engine::Session;
+use solvecraft_engine::render::{StandardView, render_png};
+
+const USAGE: &str = "usage:
+  solvecraft-cli run <script.json|design.solvecraft> [--out FILE]... [--save FILE] [--quiet]
+  solvecraft-cli eval <script.json|design.solvecraft>     (alias: inspect)
+  solvecraft-cli snapshot <script|design> --out shot.png [--width W] [--height H] [--view iso|front|back|top|bottom|left|right]
+  solvecraft-cli exec <command> [json-params]
+  solvecraft-cli commands
+  solvecraft-cli recipe <recipe.json>
+  solvecraft-cli oracle <case-dir>... [--json]
+";
+
+fn main() -> ExitCode {
+    let args: Vec<String> = std::env::args().skip(1).collect();
+    let r = match args.first().map(String::as_str) {
+        Some("run") => cmd_run(&args[1..]),
+        Some("eval" | "inspect") => cmd_eval(&args[1..]),
+        Some("snapshot") => cmd_snapshot(&args[1..]),
+        Some("exec") => cmd_exec(&args[1..]),
+        Some("commands") => {
+            let mut s = Session::default();
+            s.execute("engine.commands", &json!({})).map(|v| println!("{}", pretty(&v))).map_err(|e| e.to_string())
+        }
+        Some("recipe") => args.get(1).ok_or_else(|| USAGE.to_string()).and_then(|p| {
+            let v = read_json(p)?;
+            recipe::to_script(&v).map(|s| println!("{}", pretty(&s)))
+        }),
+        Some("oracle") => oracle::run(&args[1..]),
+        Some("--version" | "-V") => {
+            println!("solvecraft-cli {}", env!("CARGO_PKG_VERSION"));
+            Ok(())
+        }
+        _ => Err(USAGE.to_string()),
+    };
+    match r {
+        Ok(()) => ExitCode::SUCCESS,
+        Err(e) => {
+            eprintln!("error: {e}");
+            ExitCode::FAILURE
+        }
+    }
+}
+
+fn pretty(v: &Value) -> String {
+    serde_json::to_string_pretty(v).unwrap_or_default()
+}
+
+pub fn read_json(path: &str) -> Result<Value, String> {
+    let s = std::fs::read_to_string(path).map_err(|e| format!("{path}: {e}"))?;
+    serde_json::from_str(&s).map_err(|e| format!("{path}: {e}"))
+}
+
+/// A session from a design file, a command script, or an oracle recipe.
+pub fn load(path: &str) -> Result<Session, String> {
+    let v = read_json(path)?;
+    let mut s = Session::default();
+    if v.get("format").and_then(Value::as_str).is_some_and(|f| f.starts_with("solvecraft")) {
+        s.execute("doc.open", &json!({"path": path})).map_err(|e| e.to_string())?;
+    } else if v.get("features").is_some() && v.get("commands").is_none() {
+        let script = recipe::to_script(&v)?;
+        s.run_script(&script).map_err(|e| e.to_string())?;
+    } else {
+        s.run_script(&v).map_err(|e| e.to_string())?;
+    }
+    Ok(s)
+}
+
+fn flag<'a>(args: &'a [String], name: &str) -> Option<&'a str> {
+    args.iter().position(|a| a == name).and_then(|i| args.get(i + 1)).map(String::as_str)
+}
+
+fn flags<'a>(args: &'a [String], name: &str) -> Vec<&'a str> {
+    args.windows(2).filter(|w| w[0] == name).map(|w| w[1].as_str()).collect()
+}
+
+fn cmd_run(args: &[String]) -> Result<(), String> {
+    let path = args.first().ok_or_else(|| USAGE.to_string())?;
+    let mut s = load(path)?;
+    for out in flags(args, "--out") {
+        s.execute("ExportCommand", &json!({"path": out})).map_err(|e| e.to_string())?;
+    }
+    if let Some(p) = flag(args, "--save") {
+        s.execute("SaveDocumentAsCommand", &json!({"path": p})).map_err(|e| e.to_string())?;
+    }
+    if !args.iter().any(|a| a == "--quiet") {
+        let m = s.execute("MeasureCommand", &json!({})).map_err(|e| e.to_string())?;
+        println!("{}", pretty(&m));
+    }
+    Ok(())
+}
+
+fn cmd_eval(args: &[String]) -> Result<(), String> {
+    let path = args.first().ok_or_else(|| USAGE.to_string())?;
+    let mut s = load(path)?;
+    let m = s.execute("MeasureCommand", &json!({})).map_err(|e| e.to_string())?;
+    let d = s.execute("document.inspect", &json!({})).map_err(|e| e.to_string())?;
+    let out = json!({
+        "body_count": m["body_count"],
+        "bodies": m["bodies"],
+        "total": m["total"],
+        "timeline": d["timeline"],
+        "params": d["params"],
+        "sketches": d["sketches"],
+    });
+    println!("{}", pretty(&out));
+    Ok(())
+}
+
+fn cmd_snapshot(args: &[String]) -> Result<(), String> {
+    let path = args.first().ok_or_else(|| USAGE.to_string())?;
+    let out = flag(args, "--out").ok_or("snapshot needs --out FILE.png")?;
+    let w = flag(args, "--width").and_then(|x| x.parse().ok()).unwrap_or(1280usize);
+    let h = flag(args, "--height").and_then(|x| x.parse().ok()).unwrap_or(800usize);
+    let s = load(path)?;
+    let mut cam = solvecraft_engine::view::home_camera(&s);
+    if let Some(v) = flag(args, "--view") {
+        cam.set_view(StandardView::parse(v).ok_or_else(|| format!("unknown view `{v}`"))?);
+    }
+    let scene = solvecraft_engine::view::scene(&s, &cam);
+    let png = render_png(&scene, &cam, w, h).ok_or("render failed")?;
+    std::fs::write(out, &png).map_err(|e| format!("{out}: {e}"))?;
+    println!("{}", pretty(&json!({"path": out, "width": w, "height": h, "bytes": png.len()})));
+    Ok(())
+}
+
+fn cmd_exec(args: &[String]) -> Result<(), String> {
+    let id = args.first().ok_or_else(|| USAGE.to_string())?;
+    let p: Value = match args.get(1) {
+        Some(t) => serde_json::from_str(t).map_err(|e| format!("params: {e}"))?,
+        None => json!({}),
+    };
+    let mut s = Session::default();
+    let v = s.execute(id, &p).map_err(|e| e.to_string())?;
+    println!("{}", pretty(&v));
+    Ok(())
+}
diff --git a/apps/solvecraft-cli/src/oracle.rs b/apps/solvecraft-cli/src/oracle.rs
new file mode 100644
index 00000000..f3c9a2e5
--- /dev/null
+++ b/apps/solvecraft-cli/src/oracle.rs
@@ -0,0 +1,83 @@
+//! Replay oracle recipes and compare with Fusion's measurements.
+
+use serde_json::{Value, json};
+
+use crate::{read_json, recipe};
+
+/// Relative tolerance for volume and area (our curved-face tessellation is within ~2e-4).
+pub const REL_TOL: f64 = 1e-3;
+
+fn check_case(dir: &str) -> Value {
+    let name = std::path::Path::new(dir).file_name().map(|x| x.to_string_lossy().to_string()).unwrap_or_default();
+    let rp = format!("{dir}/recipe.json");
+    let mp = format!("{dir}/measure.json");
+    let (recipe, want) = match (read_json(&rp), read_json(&mp)) {
+        (Ok(r), Ok(m)) => (r, m),
+        (Err(e), _) | (_, Err(e)) => return json!({"case": name, "pass": false, "error": e}),
+    };
+    let script = match recipe::to_script(&recipe) {
+        Ok(s) => s,
+        Err(e) => return json!({"case": name, "pass": false, "skipped": true, "error": e}),
+    };
+    let mut s = solvecraft_engine::Session::default();
+    if let Err(e) = s.run_script(&script) {
+        return json!({"case": name, "pass": false, "error": e.to_string()});
+    }
+    let got = match s.execute("MeasureCommand", &json!({})) {
+        Ok(m) => m,
+        Err(e) => return json!({"case": name, "pass": false, "error": e.to_string()}),
+    };
+    let mut checks = Vec::new();
+    let mut pass = true;
+    let mut num = |what: &str, g: Option<f64>, w: Option<f64>, rel: f64| {
+        let ok = match (g, w) {
+            (Some(g), Some(w)) => (g - w).abs() <= rel * w.abs().max(1.0),
+            _ => false,
+        };
+        pass &= ok;
+        checks.push(json!({"check": what, "got": g, "want": w, "ok": ok}));
+    };
+    num("body_count", got["body_count"].as_f64(), want["body_count"].as_f64(), 0.0);
+    num("volume_mm3", got["total"]["volume_mm3"].as_f64(), want["total"]["volume_mm3"].as_f64(), REL_TOL);
+    num("area_mm2", got["total"]["area_mm2"].as_f64(), want["total"]["area_mm2"].as_f64(), REL_TOL);
+    num("faces", got["total"]["faces"].as_f64(), want["total"]["faces"].as_f64(), 0.0);
+    num("edges", got["total"]["edges"].as_f64(), want["total"]["edges"].as_f64(), 0.0);
+    num("vertices", got["total"]["vertices"].as_f64(), want["total"]["vertices"].as_f64(), 0.0);
+    json!({"case": name, "pass": pass, "checks": checks})
+}
+
+pub fn run(args: &[String]) -> Result<(), String> {
+    let dirs: Vec<&String> = args.iter().filter(|a| !a.starts_with("--")).collect();
+    if dirs.is_empty() {
+        return Err("oracle: give one or more case directories".into());
+    }
+    let results: Vec<Value> = dirs.iter().map(|d| check_case(d)).collect();
+    if args.iter().any(|a| a == "--json") {
+        println!("{}", serde_json::to_string_pretty(&Value::Array(results.clone())).unwrap_or_default());
+    } else {
+        for r in &results {
+            let status = if r["pass"].as_bool().unwrap_or(false) {
+                "PASS"
+            } else if r["skipped"].as_bool().unwrap_or(false) {
+                "SKIP"
+            } else {
+                "FAIL"
+            };
+            let detail: Vec<String> = r["checks"]
+                .as_array()
+                .into_iter()
+                .flatten()
+                .filter(|c| !c["ok"].as_bool().unwrap_or(false))
+                .map(|c| format!("{} got {} want {}", c["check"].as_str().unwrap_or(""), c["got"], c["want"]))
+                .collect();
+            let err = r["error"].as_str().map(|e| format!(" ({e})")).unwrap_or_default();
+            println!(
+                "{status} {}{err}{}",
+                r["case"].as_str().unwrap_or(""),
+                if detail.is_empty() { String::new() } else { format!(": {}", detail.join("; ")) }
+            );
+        }
+    }
+    let failed = results.iter().filter(|r| !r["pass"].as_bool().unwrap_or(false) && !r["skipped"].as_bool().unwrap_or(false)).count();
+    if failed > 0 { Err(format!("{failed} oracle case(s) failed")) } else { Ok(()) }
+}
diff --git a/apps/solvecraft-cli/src/recipe.rs b/apps/solvecraft-cli/src/recipe.rs
new file mode 100644
index 00000000..3c81924f
--- /dev/null
+++ b/apps/solvecraft-cli/src/recipe.rs
@@ -0,0 +1,159 @@
+//! Oracle recipes (`plan/fusion/oracle/*/recipe.json`) → SolveCraft command scripts.
+//!
+//! A recipe lists features with sketch entities in sketch-local coordinates; point references
+//! (`l1.end`) share points. Each feature becomes one or more commands.
+
+use serde_json::{Value, json};
+
+fn plane_param(pl: &Value) -> Value {
+    let r = pl.get("ref").and_then(Value::as_str).unwrap_or("");
+    let origin_zero = pl.get("origin").and_then(Value::as_array).is_none_or(|o| o.iter().all(|x| x.as_f64().unwrap_or(0.0).abs() < 1e-12));
+    let std = match r.to_ascii_uppercase().as_str() {
+        "XY" => Some(([1.0, 0.0, 0.0], [0.0, 1.0, 0.0])),
+        "XZ" => Some(([1.0, 0.0, 0.0], [0.0, 0.0, 1.0])),
+        "YZ" => Some(([0.0, 1.0, 0.0], [0.0, 0.0, 1.0])),
+        _ => None,
+    };
+    let axes_match = |k: &str, want: [f64; 3]| {
+        pl.get(k).and_then(Value::as_array).is_some_and(|a| a.iter().zip(want).all(|(x, w)| (x.as_f64().unwrap_or(f64::NAN) - w).abs() < 1e-9))
+    };
+    match std {
+        Some((x, y)) if origin_zero && axes_match("x_dir", x) && axes_match("y_dir", y) => json!(r.to_ascii_uppercase()),
+        _ => json!({"origin": pl.get("origin").cloned().unwrap_or(json!([0, 0, 0])), "x_dir": pl.get("x_dir"), "y_dir": pl.get("y_dir")}),
+    }
+}
+
+/// A point argument: the shared reference if any, else the coordinates.
+fn parg(p: Option<&Value>) -> Value {
+    match p {
+        Some(v) => match (v.get("ref"), v.get("at")) {
+            (Some(Value::String(r)), _) => json!(r),
+            (_, Some(at)) => at.clone(),
+            _ => v.clone(),
+        },
+        None => Value::Null,
+    }
+}
+
+fn op(f: &Value) -> Value {
+    f.get("operation").cloned().unwrap_or(json!("new"))
+}
+
+fn sketch_cmds(f: &Value, out: &mut Vec<Value>) -> Result<(), String> {
+    let mut p = json!({"plane": plane_param(f.get("plane").unwrap_or(&Value::Null))});
+    if let Some(n) = f.get("name") {
+        p["name"] = n.clone();
+    }
+    out.push(json!({"command": "SketchCreate", "params": p}));
+    for e in f.get("entities").and_then(Value::as_array).into_iter().flatten() {
+        let id = e.get("id").cloned().unwrap_or(Value::Null);
+        let construction = e.get("construction").cloned().unwrap_or(json!(false));
+        match e.get("type").and_then(Value::as_str) {
+            Some("line") => out.push(json!({"command": "DrawPolyline", "params": {"points": [parg(e.get("start")), parg(e.get("end"))], "ids": [id], "construction": construction}})),
+            Some("circle") => out.push(json!({"command": "CircleCenterRadius", "params": {"center": parg(e.get("center")), "radius": e.get("radius"), "id": id, "construction": construction}})),
+            Some("arc") => {
+                if e.get("center").is_some() {
+                    out.push(json!({"command": "ArcCenterTwoPoint", "params": {"center": parg(e.get("center")), "start": parg(e.get("start")), "end": parg(e.get("end")), "id": id}}))
+                } else {
+                    out.push(json!({"command": "ArcThreePoint", "params": {"start": parg(e.get("start")), "end": parg(e.get("end")), "through": parg(e.get("through").or(e.get("mid"))), "id": id}}))
+                }
+            }
+            Some("point") => out.push(json!({"command": "DrawPoint", "params": {"point": parg(e.get("at").map(|a| json!({"at": a})).as_ref().or(Some(e))), "id": id}})),
+            Some(other) => return Err(format!("recipe: sketch entity type `{other}` is not supported yet")),
+            None => return Err("recipe: sketch entity without type".into()),
+        }
+    }
+    for c in f.get("constraints").and_then(Value::as_array).into_iter().flatten() {
+        let ty = c.get("type").and_then(Value::as_str).unwrap_or("");
+        let cmd = match ty.to_ascii_lowercase().as_str() {
+            "horizontal" | "vertical" => {
+                let mut p = c.clone();
+                p["mode"] = json!(ty.to_ascii_lowercase());
+                out.push(json!({"command": "ConstraintHorizontalVertical", "params": p}));
+                continue;
+            }
+            "coincident" => "ConstraintCoincident",
+            "tangent" => "ConstraintTangent",
+            "equal" => "ConstraintEqual",
+            "parallel" => "ConstraintParallel",
+            "perpendicular" => "ConstraintPerpendicular",
+            "fix" => "ConstraintFix",
+            "midpoint" => "ConstraintMidPoint",
+            "concentric" => "ConstraintConcentric",
+            "collinear" => "ConstraintCollinear",
+            "symmetry" | "symmetric" => "ConstraintSymmetry",
+            other => return Err(format!("recipe: constraint `{other}` is not supported yet")),
+        };
+        out.push(json!({"command": cmd, "params": c}));
+    }
+    for d in f.get("dimensions").and_then(Value::as_array).into_iter().flatten() {
+        out.push(json!({"command": "SketchDimension", "params": d}));
+    }
+    out.push(json!({"command": "SketchStop", "params": {}}));
+    Ok(())
+}
+
+fn extent(f: &Value) -> (Value, Value, Value) {
+    let e = f.get("extent").cloned().unwrap_or(Value::Null);
+    let d = e.get("distance").cloned().or_else(|| f.get("distance").cloned()).unwrap_or(Value::Null);
+    let dir = e.get("direction").cloned().unwrap_or(json!("positive"));
+    (d, dir, e.get("distance2").cloned().unwrap_or(Value::Null))
+}
+
+/// The sketch a feature uses (name), from its profiles.
+fn profile_sketch(f: &Value) -> Value {
+    f.get("profiles")
+        .and_then(Value::as_array)
+        .and_then(|a| a.first())
+        .and_then(|p| p.get("sketch"))
+        .cloned()
+        .or_else(|| f.get("sketch").cloned())
+        .unwrap_or(Value::Null)
+}
+
+pub fn to_script(recipe: &Value) -> Result<Value, String> {
+    let mut out: Vec<Value> = Vec::new();
+    for p in recipe.get("parameters").and_then(Value::as_array).into_iter().flatten() {
+        out.push(json!({"command": "ChangeParameterCommand", "params": {"name": p.get("name"), "expression": p.get("expression").or(p.get("value")), "unit": p.get("unit").cloned().unwrap_or(json!("mm"))}}));
+    }
+    let features = recipe.get("features").and_then(Value::as_array).ok_or("recipe: missing `features`")?;
+    for f in features {
+        let name = f.get("name").cloned().unwrap_or(Value::Null);
+        let bodies = f.get("result_bodies").cloned().unwrap_or(json!([]));
+        match f.get("op").and_then(Value::as_str) {
+            Some("sketch") => sketch_cmds(f, &mut out)?,
+            Some("extrude") => {
+                let (d, dir, d2) = extent(f);
+                let mut p = json!({"sketch": profile_sketch(f), "profiles": f.get("profiles").cloned().unwrap_or(json!("all")), "distance": d, "direction": dir, "operation": op(f), "name": name, "body_names": bodies});
+                if !d2.is_null() {
+                    p["distance2"] = d2;
+                }
+                out.push(json!({"command": "Extrude", "params": p}));
+            }
+            Some("revolve") => out.push(json!({"command": "Revolve", "params": {
+                "sketch": profile_sketch(f), "profiles": f.get("profiles").cloned().unwrap_or(json!("all")),
+                "axis": f.get("axis").and_then(|a| a.get("ref").or(a.get("line")).cloned()).or_else(|| f.get("axis").cloned()),
+                "angle": f.get("angle").cloned().unwrap_or(json!("360 deg")), "operation": op(f), "name": name, "body_names": bodies}})),
+            Some("fillet") => {
+                out.push(json!({"command": "FusionFilletEdgesCommand", "params": {"edges": edge_points(f), "radius": f.get("radius"), "name": name}}))
+            }
+            Some("chamfer") => {
+                out.push(json!({"command": "FusionChamferCommand", "params": {"edges": edge_points(f), "distance": f.get("distance"), "name": name}}))
+            }
+            Some(other) => return Err(format!("recipe: feature op `{other}` is not supported yet")),
+            None => return Err("recipe: feature without `op`".into()),
+        }
+    }
+    Ok(json!({"commands": out}))
+}
+
+fn edge_points(f: &Value) -> Value {
+    Value::Array(
+        f.get("edges")
+            .and_then(Value::as_array)
+            .into_iter()
+            .flatten()
+            .map(|e| e.get("point").or(e.get("mid")).cloned().unwrap_or_else(|| e.clone()))
+            .collect(),
+    )
+}
diff --git a/crates/engine/Cargo.toml b/crates/engine/Cargo.toml
index 8671370b..e397b7a3 100644
--- a/crates/engine/Cargo.toml
+++ b/crates/engine/Cargo.toml
@@ -14,6 +14,7 @@ solvecraft-sketch = { workspace = true }
 solvecraft-kernel = { workspace = true }
 solvecraft-doc = { workspace = true }
 solvecraft-io = { workspace = true }
+solvecraft-render = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 thiserror = { workspace = true }
diff --git a/crates/engine/src/lib.rs b/crates/engine/src/lib.rs
index b2f278ad..9540b1a5 100644
--- a/crates/engine/src/lib.rs
+++ b/crates/engine/src/lib.rs
@@ -10,6 +10,7 @@
 
 pub mod cmd;
 pub mod params;
+pub mod view;
 
 use std::sync::Arc;
 
@@ -23,6 +24,7 @@ pub use solvecraft_doc as doc;
 pub use solvecraft_geom as geom;
 pub use solvecraft_io as io;
 pub use solvecraft_kernel as kernel;
+pub use solvecraft_render as render;
 pub use solvecraft_sketch as sketch;
 
 #[derive(Debug, thiserror::Error)]
diff --git a/crates/engine/src/view.rs b/crates/engine/src/view.rs
new file mode 100644
index 00000000..2a7ffbec
--- /dev/null
+++ b/crates/engine/src/view.rs
@@ -0,0 +1,142 @@
+//! What the viewport shows, independent of the UI toolkit: body meshes, edges, sketches, the
+//! grid and the origin. Used by the headless snapshot renderer; the GPU viewport draws the same
+//! content.
+
+use std::sync::Arc;
+
+use solvecraft_geom::{Aabb3, Plane, Vec3};
+use solvecraft_render::{Camera, Rgb, Scene, SceneLine, SceneMesh};
+use solvecraft_sketch::Sketch;
+
+use crate::{Sel, Session};
+
+/// Colours (shared with the GPU viewport).
+pub mod colors {
+    use solvecraft_render::Rgb;
+    pub const BODY: Rgb = Rgb(176, 186, 198);
+    pub const BODY_SELECTED: Rgb = Rgb(110, 170, 235);
+    pub const EDGE: Rgb = Rgb(40, 44, 52);
+    pub const SKETCH: Rgb = Rgb(30, 90, 200);
+    pub const SKETCH_DONE: Rgb = Rgb(20, 20, 20);
+    pub const SKETCH_CONSTRUCTION: Rgb = Rgb(230, 130, 40);
+    pub const SKETCH_FIXED: Rgb = Rgb(20, 20, 20);
+    pub const PROFILE: Rgb = Rgb(255, 196, 120);
+    pub const GRID: Rgb = Rgb(196, 202, 212);
+    pub const GRID_MAJOR: Rgb = Rgb(170, 178, 190);
+    pub const AXIS_X: Rgb = Rgb(220, 60, 60);
+    pub const AXIS_Y: Rgb = Rgb(60, 170, 60);
+    pub const AXIS_Z: Rgb = Rgb(60, 100, 230);
+    pub const BG_TOP: Rgb = Rgb(240, 243, 247);
+    pub const BG_BOTTOM: Rgb = Rgb(203, 210, 221);
+}
+
+/// Bounds of everything visible.
+pub fn bounds(s: &Session) -> Aabb3 {
+    let st = s.model.state();
+    let mut b = Aabb3::EMPTY;
+    for body in &st.bodies {
+        b = b.union(&body.mesh().bounds());
+    }
+    for ss in &st.sketches {
+        if let Some((lo, hi)) = ss.sketch.bounds() {
+            for p in [lo, hi] {
+                b.add(ss.plane.to_world(p));
+            }
+        }
+    }
+    b
+}
+
+/// Grid spacing (minor, major) for a view of the given half height.
+pub fn grid_step(half_height: f64) -> (f64, f64) {
+    let raw = (half_height / 10.0).max(1e-3);
+    let p = 10f64.powf(raw.log10().floor());
+    let minor = if raw / p < 2.0 {
+        p
+    } else if raw / p < 5.0 {
+        2.0 * p
+    } else {
+        5.0 * p
+    };
+    (minor, minor * 5.0)
+}
+
+/// Sketch curves as world polylines with their colour.
+pub fn sketch_lines(sk: &Sketch, plane: &Plane, active: bool, determined: &[bool]) -> Vec<(Vec<Vec3>, Rgb, bool)> {
+    let mut out = Vec::new();
+    for (i, c) in sk.curves.iter().enumerate() {
+        let col = if c.construction {
+            colors::SKETCH_CONSTRUCTION
+        } else if !active {
+            colors::SKETCH_DONE
+        } else if determined.get(i).copied().unwrap_or(false) {
+            colors::SKETCH_FIXED
+        } else {
+            colors::SKETCH
+        };
+        for seg in sk.segs(i) {
+            out.push((seg.polyline(0.02).iter().map(|p| plane.to_world(*p)).collect(), col, c.construction));
+        }
+    }
+    out
+}
+
+/// The scene for a headless render.
+pub fn scene(s: &Session, cam: &Camera) -> Scene {
+    let st = s.model.state();
+    let mut sc = Scene { background: Some((colors::BG_TOP, colors::BG_BOTTOM)), ..Default::default() };
+    let b = bounds(s);
+    sc.radius = (b.diagonal() * 0.5).max(cam.half_height()).max(10.0) + b.center().dist(cam.target);
+    // Grid on XY.
+    let (minor, major) = grid_step(cam.half_height());
+    let ext = (cam.half_height() * 3.0 / major).ceil() * major;
+    let c = Vec3::new((cam.target.x / major).round() * major, (cam.target.y / major).round() * major, 0.0);
+    let n = ((ext / minor) as i64).clamp(1, 400);
+    for i in -n..=n {
+        let t = i as f64 * minor;
+        let col = if (t / major).fract().abs() < 1e-9 { colors::GRID_MAJOR } else { colors::GRID };
+        sc.lines.push(SceneLine { points: vec![c + Vec3::new(t, -ext, 0.0), c + Vec3::new(t, ext, 0.0)], color: col, width: 0.6, on_top: false });
+        sc.lines.push(SceneLine { points: vec![c + Vec3::new(-ext, t, 0.0), c + Vec3::new(ext, t, 0.0)], color: col, width: 0.6, on_top: false });
+    }
+    let axis = cam.half_height() * 0.25;
+    for (d, col) in [(Vec3::X, colors::AXIS_X), (Vec3::Y, colors::AXIS_Y), (Vec3::Z, colors::AXIS_Z)] {
+        sc.lines.push(SceneLine { points: vec![Vec3::ZERO, d * axis], color: col, width: 1.6, on_top: false });
+    }
+    for body in &st.bodies {
+        let selected = s.selection.iter().any(|x| matches!(x, Sel::Body { name } if *name == body.name));
+        let mesh = body.mesh();
+        sc.meshes.push(SceneMesh { mesh: Arc::clone(&mesh), color: if selected { colors::BODY_SELECTED } else { colors::BODY } });
+        for e in &mesh.edges {
+            sc.lines.push(SceneLine { points: e.clone(), color: colors::EDGE, width: 1.2, on_top: false });
+        }
+    }
+    for ss in &st.sketches {
+        let active = s.active_sketch == Some(ss.feature);
+        // Finished sketches are hidden once a feature uses them, like Fusion's default.
+        if !active && sketch_consumed(s, ss.feature) {
+            continue;
+        }
+        for (pts, col, cons) in sketch_lines(&ss.sketch, &ss.plane, active, &ss.report.curve_determined) {
+            sc.lines.push(SceneLine { points: pts, color: col, width: if cons { 1.0 } else { 1.6 }, on_top: active });
+        }
+    }
+    sc
+}
+
+/// Is a sketch used by a later feature?
+pub fn sketch_consumed(s: &Session, id: u64) -> bool {
+    use solvecraft_doc::FeatureKind;
+    s.doc.features.iter().any(|f| matches!(f.kind, FeatureKind::Extrude { sketch, .. } | FeatureKind::Revolve { sketch, .. } if sketch == id))
+}
+
+/// Camera framing the model (iso view).
+pub fn home_camera(s: &Session) -> Camera {
+    let mut c = Camera::default();
+    let b = bounds(s);
+    if !b.is_empty() {
+        c.fit(&b);
+    } else {
+        c.distance = 150.0;
+    }
+    c
+}
diff --git a/crates/render/src/raster.rs b/crates/render/src/raster.rs
index 22f0a913..fd7cf24c 100644
--- a/crates/render/src/raster.rs
+++ b/crates/render/src/raster.rs
@@ -73,7 +73,7 @@ fn shade(n: Vec3, view_dir: Vec3, base: [f64; 3]) -> [f64; 3] {
     let fill = n.dot(view_dir).max(0.0);
     let h = (key + view_dir).normalized().unwrap_or(view_dir);
     let spec = n.dot(h).max(0.0).powi(40) * 0.25;
-    let k = 0.28 + 0.52 * diff + 0.22 * fill;
+    let k = 0.42 + 0.38 * diff + 0.25 * fill;
     [(base[0] * k + spec).min(1.0), (base[1] * k + spec).min(1.0), (base[2] * k + spec).min(1.0)]
 }