Merge branch 'buffer-implementation'HEADmain

Establishes the first working baseline: moji <file> opens a file into a
ropey rope and edits it with Helix selection-first modal editing, under a
DO-178C DAL-C requirements and traceability process.

Prior to this, main tracked four files and src/main.rs was still
println!("Hello, world!") — there was no buildable state to build on.

Verified on a fresh clone of the branch with no untracked files:
cargo build; clippy --all-targets -D warnings clean; 294 tests passing;
scripts/check-trace.sh reports 98/98 requirements traced in both
directions.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/build.rs b/build.rs
new file mode 100644
index 0000000..20c813a
--- /dev/null
+++ b/build.rs
@@ -0,0 +1,37 @@
+use anyhow::Result;
+use vergen_gix::{Build, Cargo, Emitter, Gix};
+
+/// Fallback used when the crate is built outside a git checkout (e.g. from a
+/// packaged `.crate` file), so `env!("VERGEN_GIT_REMOTE_URL")` always resolves.
+const UNKNOWN_REMOTE: &str = "unknown";
+
+fn main() -> Result<()> {
+    let build = Build::all_build();
+    let gix = Gix::all_git();
+    let cargo = Cargo::all_cargo();
+    Emitter::default()
+        .default_on_error()
+        .add_instructions(&build)?
+        .add_instructions(&gix)?
+        .add_instructions(&cargo)?
+        .emit()?;
+
+    emit_git_remote_url();
+    Ok(())
+}
+
+/// vergen only reports the local checkout (sha, branch, describe...), so read the
+/// `origin` remote out of the same repository and expose it alongside the rest of
+/// the `VERGEN_GIT_*` variables.
+fn emit_git_remote_url() {
+    let url = git_remote_url().unwrap_or_else(|| UNKNOWN_REMOTE.to_string());
+    println!("cargo:rustc-env=VERGEN_GIT_REMOTE_URL={url}");
+    println!("cargo:rerun-if-changed=.git/config");
+}
+
+fn git_remote_url() -> Option<String> {
+    let repo = gix::discover(env!("CARGO_MANIFEST_DIR")).ok()?;
+    let remote = repo.find_remote("origin").ok()?;
+    let url = remote.url(gix::remote::Direction::Fetch)?;
+    Some(url.to_bstring().to_string())
+}