diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ea8c4bf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..788d761
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,39 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "vernier-app"
+version = "0.0.1"
+
+[[package]]
+name = "vernier-cli"
+version = "0.0.1"
+
+[[package]]
+name = "vernier-doc"
+version = "0.0.1"
+
+[[package]]
+name = "vernier-kernel"
+version = "0.0.1"
+
+[[package]]
+name = "vernier-occt-sys"
+version = "0.0.1"
+
+[[package]]
+name = "vernier-render"
+version = "0.0.1"
+
+[[package]]
+name = "vernier-solver"
+version = "0.0.1"
+
+[[package]]
+name = "vernier-tess"
+version = "0.0.1"
+
+[[package]]
+name = "vernier-ui"
+version = "0.0.1"
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..a106535
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,25 @@
+[workspace]
+resolver = "3"
+members = ["crates/*"]
+
+[workspace.package]
+version = "0.0.1"
+edition = "2024"
+rust-version = "1.96"
+license = "GPL-3.0-or-later"
+repository = "https://git.briggen.dev/NilsBriggen/vernier"
+publish = false
+
+[workspace.dependencies]
+indexmap = "2"
+thiserror = "2"
+tracing = "0.1"
+
+# Deny-by-default discipline from CLAUDE.md. Test code may locally
+# `#[allow(clippy::unwrap_used)]` — production code may not.
+[workspace.lints.rust]
+missing_docs = "deny"
+
+[workspace.lints.clippy]
+unwrap_used = "deny"
+expect_used = "deny"
diff --git a/crates/vernier-app/Cargo.toml b/crates/vernier-app/Cargo.toml
new file mode 100644
index 0000000..f3dc766
--- /dev/null
+++ b/crates/vernier-app/Cargo.toml
@@ -0,0 +1,18 @@
+[package]
+name = "vernier-app"
+description = "VernierCAD desktop application"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+repository.workspace = true
+publish.workspace = true
+
+[features]
+# Forward to vernier-occt-sys/system-occt once the kernel dependency chain
+# reaches this crate (Phase 1). Declared now so
+# `cargo run -p vernier-app --features system-occt` works as documented.
+system-occt = []
+
+[lints]
+workspace = true
diff --git a/crates/vernier-app/src/main.rs b/crates/vernier-app/src/main.rs
new file mode 100644
index 0000000..e6aae9c
--- /dev/null
+++ b/crates/vernier-app/src/main.rs
@@ -0,0 +1,9 @@
+//! Thin `main()` for the VernierCAD desktop application.
+//!
+//! Everything of substance lives in the library crates; this binary only
+//! wires them together. The egui/wgpu shell arrives with the Phase 0 render
+//! milestone.
+
+#![forbid(unsafe_code)]
+
+fn main() {}
diff --git a/crates/vernier-cli/Cargo.toml b/crates/vernier-cli/Cargo.toml
new file mode 100644
index 0000000..8073850
--- /dev/null
+++ b/crates/vernier-cli/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "vernier-cli"
+description = "Headless driver for scripting and testing"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+repository.workspace = true
+publish.workspace = true
+
+[lints]
+workspace = true
diff --git a/crates/vernier-cli/src/main.rs b/crates/vernier-cli/src/main.rs
new file mode 100644
index 0000000..a6566a2
--- /dev/null
+++ b/crates/vernier-cli/src/main.rs
@@ -0,0 +1,32 @@
+//! Headless driver for VernierCAD — the primary verification path.
+//!
+//! Every modelling operation must be drivable through this binary with no
+//! window, no GPU, and no display, producing a deterministic artifact that
+//! can be asserted on. A feature that cannot be exercised here is not
+//! finished.
+
+#![forbid(unsafe_code)]
+
+use std::process::ExitCode;
+
+fn main() -> ExitCode {
+    let args: Vec<String> = std::env::args().skip(1).collect();
+    match args.first().map(String::as_str) {
+        Some("--selftest") => selftest(),
+        _ => {
+            eprintln!("usage: vernier-cli --selftest");
+            ExitCode::FAILURE
+        }
+    }
+}
+
+/// Runs every registered self-check headlessly and prints a JSON report to
+/// stdout. The report must be byte-identical across runs (invariant #1).
+///
+/// Phase 0 gate: passes with no display attached. Subsystem checks register
+/// here as they land; an empty run still proves the binary works headless.
+fn selftest() -> ExitCode {
+    let report = r#"{"selftest":"pass","checks":[]}"#;
+    println!("{report}");
+    ExitCode::SUCCESS
+}
diff --git a/crates/vernier-cli/tests/selftest.rs b/crates/vernier-cli/tests/selftest.rs
new file mode 100644
index 0000000..cdd11f6
--- /dev/null
+++ b/crates/vernier-cli/tests/selftest.rs
@@ -0,0 +1,32 @@
+//! The Phase 0 gate: `--selftest` passes with no display, deterministically.
+
+#![allow(clippy::unwrap_used)]
+
+use std::process::{Command, Output};
+
+fn run_selftest() -> Output {
+    Command::new(env!("CARGO_BIN_EXE_vernier-cli"))
+        .arg("--selftest")
+        .env_remove("DISPLAY")
+        .env_remove("WAYLAND_DISPLAY")
+        .output()
+        .unwrap()
+}
+
+#[test]
+fn selftest_passes_headless() {
+    let out = run_selftest();
+    assert!(out.status.success(), "selftest exited non-zero");
+    let report = String::from_utf8(out.stdout).unwrap();
+    assert!(report.contains(r#""selftest":"pass""#), "report: {report}");
+}
+
+#[test]
+fn selftest_output_is_deterministic() {
+    let first = run_selftest();
+    let second = run_selftest();
+    assert_eq!(
+        first.stdout, second.stdout,
+        "selftest output differs between runs — invariant #1 violated"
+    );
+}
diff --git a/crates/vernier-doc/Cargo.toml b/crates/vernier-doc/Cargo.toml
new file mode 100644
index 0000000..1b7a612
--- /dev/null
+++ b/crates/vernier-doc/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "vernier-doc"
+description = "Document model: feature DAG, EntityId space, undo stack, serialization"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+repository.workspace = true
+publish.workspace = true
+
+[lints]
+workspace = true
diff --git a/crates/vernier-doc/src/lib.rs b/crates/vernier-doc/src/lib.rs
new file mode 100644
index 0000000..af4a295
--- /dev/null
+++ b/crates/vernier-doc/src/lib.rs
@@ -0,0 +1,7 @@
+//! Document model: feature DAG, `EntityId` allocation, undo stack, serialization.
+//!
+//! `EntityId`s are allocated here and mapped through the kernel façade —
+//! entity identity never derives from an index or a pointer. Like
+//! `vernier-solver`, this crate must never depend on `vernier-kernel`.
+
+#![forbid(unsafe_code)]
diff --git a/crates/vernier-kernel/Cargo.toml b/crates/vernier-kernel/Cargo.toml
new file mode 100644
index 0000000..dc3acd2
--- /dev/null
+++ b/crates/vernier-kernel/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "vernier-kernel"
+description = "Kernel abstraction: trait Kernel, OpResult, EntityId"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+repository.workspace = true
+publish.workspace = true
+
+[lints]
+workspace = true
diff --git a/crates/vernier-kernel/src/lib.rs b/crates/vernier-kernel/src/lib.rs
new file mode 100644
index 0000000..b5f2ba4
--- /dev/null
+++ b/crates/vernier-kernel/src/lib.rs
@@ -0,0 +1,8 @@
+//! Kernel abstraction: `trait Kernel`, `OpResult`, `EntityId`.
+//!
+//! Every kernel operation returns a shape *plus a history delta* describing
+//! which entities were generated, modified, or deleted — an operation that
+//! returns a bare shape is incomplete. The OCCT implementation lives behind
+//! this boundary so hot paths can be replaced later without touching callers.
+
+#![forbid(unsafe_code)]
diff --git a/crates/vernier-occt-sys/Cargo.toml b/crates/vernier-occt-sys/Cargo.toml
new file mode 100644
index 0000000..6f80649
--- /dev/null
+++ b/crates/vernier-occt-sys/Cargo.toml
@@ -0,0 +1,18 @@
+[package]
+name = "vernier-occt-sys"
+description = "cxx bridge and C++ facade to the OCCT geometry kernel"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+repository.workspace = true
+publish.workspace = true
+
+[features]
+# Build against the distro OCCT package instead of the vendored submodule.
+# No-op until the Phase 1 bridge lands; declared now so the fast-iteration
+# commands documented in CLAUDE.md work from day one.
+system-occt = []
+
+[lints]
+workspace = true
diff --git a/crates/vernier-occt-sys/src/lib.rs b/crates/vernier-occt-sys/src/lib.rs
new file mode 100644
index 0000000..f57ef89
--- /dev/null
+++ b/crates/vernier-occt-sys/src/lib.rs
@@ -0,0 +1,9 @@
+//! FFI bridge to OCCT via a thin C++ façade with opaque `u64` shape handles.
+//!
+//! This is the **only** crate in the workspace permitted `unsafe`. The façade
+//! owns a shape registry on the C++ side; OCCT's `Handle<T>` never crosses the
+//! FFI boundary, and every OCCT exception is caught in C++ and converted to a
+//! result code before it can unwind into Rust.
+//!
+//! The bridge itself arrives in Phase 1. `facade.hpp` will be the complete API
+//! surface.
diff --git a/crates/vernier-render/Cargo.toml b/crates/vernier-render/Cargo.toml
new file mode 100644
index 0000000..ad462f5
--- /dev/null
+++ b/crates/vernier-render/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "vernier-render"
+description = "wgpu renderer with ID-buffer picking"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+repository.workspace = true
+publish.workspace = true
+
+[lints]
+workspace = true
diff --git a/crates/vernier-render/src/lib.rs b/crates/vernier-render/src/lib.rs
new file mode 100644
index 0000000..cb35b7f
--- /dev/null
+++ b/crates/vernier-render/src/lib.rs
@@ -0,0 +1,8 @@
+//! wgpu renderer: viewport, camera, ID-buffer picking.
+//!
+//! The render thread is sacred — it never blocks on the kernel. Kernel work
+//! runs on a worker; the viewport orbits at refresh rate during an
+//! eight-second recompute or the design is wrong. Target GPU is AMD RDNA3 via
+//! Mesa/RADV (Vulkan); never assume NVIDIA.
+
+#![forbid(unsafe_code)]
diff --git a/crates/vernier-solver/Cargo.toml b/crates/vernier-solver/Cargo.toml
new file mode 100644
index 0000000..07252d3
--- /dev/null
+++ b/crates/vernier-solver/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "vernier-solver"
+description = "2D sketch constraint solver (sparse Jacobian, Levenberg-Marquardt)"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+repository.workspace = true
+publish.workspace = true
+
+[lints]
+workspace = true
diff --git a/crates/vernier-solver/src/lib.rs b/crates/vernier-solver/src/lib.rs
new file mode 100644
index 0000000..5d6f75e
--- /dev/null
+++ b/crates/vernier-solver/src/lib.rs
@@ -0,0 +1,8 @@
+//! 2D sketch constraint solver: sparse Jacobian + Levenberg–Marquardt.
+//!
+//! Depends on **nothing** from the kernel layer, by design — that is what
+//! keeps it fast to test and small enough to reason about in one sitting.
+//! If a task here seems to need `vernier-kernel`, the abstraction is wrong;
+//! raise it rather than adding the dependency.
+
+#![forbid(unsafe_code)]
diff --git a/crates/vernier-tess/Cargo.toml b/crates/vernier-tess/Cargo.toml
new file mode 100644
index 0000000..02d9b99
--- /dev/null
+++ b/crates/vernier-tess/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "vernier-tess"
+description = "Tessellation and tessellation cache"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+repository.workspace = true
+publish.workspace = true
+
+[lints]
+workspace = true
diff --git a/crates/vernier-tess/src/lib.rs b/crates/vernier-tess/src/lib.rs
new file mode 100644
index 0000000..d7ee5f0
--- /dev/null
+++ b/crates/vernier-tess/src/lib.rs
@@ -0,0 +1,3 @@
+//! Tessellation of kernel shapes into render meshes, plus the tessellation cache.
+
+#![forbid(unsafe_code)]
diff --git a/crates/vernier-ui/Cargo.toml b/crates/vernier-ui/Cargo.toml
new file mode 100644
index 0000000..e4c1584
--- /dev/null
+++ b/crates/vernier-ui/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "vernier-ui"
+description = "egui shell: viewport widget, timeline"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+repository.workspace = true
+publish.workspace = true
+
+[lints]
+workspace = true
diff --git a/crates/vernier-ui/src/lib.rs b/crates/vernier-ui/src/lib.rs
new file mode 100644
index 0000000..86c55af
--- /dev/null
+++ b/crates/vernier-ui/src/lib.rs
@@ -0,0 +1,7 @@
+//! egui application shell: viewport widget, timeline, panels.
+//!
+//! egui sits behind an abstraction so it can be swapped later without
+//! touching the rest of the stack. Degrees exist only at this boundary —
+//! everything below works in radians and millimetres.
+
+#![forbid(unsafe_code)]
diff --git a/scripts/check.fish b/scripts/check.fish
new file mode 100755
index 0000000..adae1f4
--- /dev/null
+++ b/scripts/check.fish
@@ -0,0 +1,7 @@
+#!/usr/bin/env fish
+# Full check — must pass before any commit.
+
+cargo fmt --check
+and cargo clippy --all-targets -- -D warnings
+and cargo test --workspace
+and cargo run -q -p vernier-cli -- --selftest