WIP improvise-2bac: interactive arm is parse-then-contextualize

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VdfEGXA7aJ6ftMsCc9PJze

tests/headless_cli.rs

@@ -357,3 +357,82 @@ fn an_explicit_coordinate_still_beats_the_cursor() {
         "the named cell survived: {left:?}"
     );
 }
+
+/// North=1, South=2, East=3 on the row axis; the cursor starts on North.
+fn three_cells(scratch: &Scratch, name: &str) -> PathBuf {
+    let doc = three_rows(scratch, name);
+    run_cmd(
+        &[
+            "set-cell 1 Region/North",
+            "set-cell 2 Region/South",
+            "set-cell 3 Region/East",
+        ],
+        &doc,
+    );
+    assert_eq!(cell_lines(&doc).len(), 3, "the fixture wrote three cells");
+    doc
+}
+
+fn value_of(doc: &Path, item: &str) -> Option<String> {
+    cell_lines(doc)
+        .into_iter()
+        .find(|l| l.contains(&format!("Region={item}")))
+        .and_then(|l| l.rsplit(" = ").next().map(str::to_string))
+}
+
+/// Evidence: `context/test-evidence/cli.md`.
+#[test]
+fn commit_cell_edit_writes_the_named_cell_and_spares_the_cursors() {
+    let scratch = Scratch::new("commit-explicit");
+    let doc = three_cells(&scratch, "commit.improv");
+
+    let out = run_cmd(
+        &["move-selection 1 0 . commit-cell-edit editing 5 Region/East"],
+        &doc,
+    );
+    assert!(out.status.success(), "the line failed: {}", stderr_of(&out));
+    let cells = cell_lines(&doc);
+    assert_eq!(value_of(&doc, "East").as_deref(), Some("5"), "{cells:?}");
+    assert_eq!(
+        value_of(&doc, "South").as_deref(),
+        Some("2"),
+        "the cell under the cursor was touched: {cells:?}"
+    );
+    assert_eq!(
+        value_of(&doc, "North").as_deref(),
+        Some("1"),
+        "the origin cell was touched: {cells:?}"
+    );
+}
+
+/// Evidence: `context/test-evidence/cli.md`.
+#[test]
+fn a_line_whose_gate_passes_runs_whole() {
+    let scratch = Scratch::new("commit-atomic");
+    let doc = scratch.path("atomic.improv");
+    let out = run_cmd(&["add-category Foo . commit-cell-edit editing 5 Foo/x"], &doc);
+    assert!(
+        !stderr_of(&out).contains("Parse error"),
+        "a line the gate accepted was refused part-way: {}",
+        stderr_of(&out)
+    );
+    let text = std::fs::read_to_string(&doc).expect("the document");
+    assert!(
+        text.lines().any(|l| l.contains("Foo=x") && l.ends_with("= 5")),
+        "the commit did not land: {text}"
+    );
+}
+
+/// Evidence: `context/test-evidence/cli.md`.
+#[test]
+fn a_malformed_commit_line_is_refused_whole() {
+    let scratch = Scratch::new("commit-malformed");
+    let doc = seeded(&scratch, "malformed.improv");
+    let out = run_cmd(&["add-category Foo . commit-cell-edit editing 5"], &doc);
+    assert!(!out.status.success(), "a malformed line exited 0");
+    let text = std::fs::read_to_string(&doc).expect("the document");
+    assert!(
+        !text.contains("Foo"),
+        "the first half of a refused line landed: {text}"
+    );
+}