diff --git a/docs/users-guide.md b/docs/users-guide.md
index b7e750bd..4243ded5 100644
--- a/docs/users-guide.md
+++ b/docs/users-guide.md
@@ -224,6 +224,19 @@ runtime branch. Runtime decisions belong in a command or script.
 
 Top-level actions support the same `foreach` and `when` keys.
 
+### Discover files with `glob`
+
+`glob(pattern)` expands a shell-style pattern to the sorted list of matching
+files while Netsuke loads the manifest, so the results become part of the
+static build graph. It pairs naturally with `foreach` to generate one target
+per matched file; a target list such as `foreach: glob('src/*.c')` produces one
+expansion per matching source.
+
+Matching is case-sensitive. `*` and `?` do not cross directory separators; use
+`**` to descend into subdirectories. Directories are excluded, so only files
+are returned. The [quick-start guide](quickstart.md) shows a complete runnable
+example.
+
 ### Define reusable macros
 
 Macros return rendered text and can accept default arguments:
@@ -407,7 +420,7 @@ Important global options include:
 - `-f, --file <FILE>`
 - `-C, --directory <DIR>`
 - `--config <FILE>`
-- `-j, --jobs <1..64>`
+- `-j, --jobs <N>` (accepts 1 to 64)
 - `-v, --verbose`
 - `--locale <LOCALE>`
 - `--no-input`
@@ -471,6 +484,12 @@ Configuration precedence, from lowest to highest, is:
 5. `NETSUKE_` environment variables.
 6. Explicit command-line options.
 
+System and user configuration are discovered from platform conventions rather
+than two separately named Netsuke layers. On Unix this means the XDG base
+directories and the home directory; on Windows it means the application-data
+directories, such as `%APPDATA%\netsuke\config.toml`. Their relative order
+follows those platform conventions.
+
 An explicit selector bypasses automatic discovery. Selectors are checked in
 this order:
 
@@ -530,9 +549,11 @@ Netsuke separates machine-consumable output from status information:
 - stdout contains generated artefacts and subprocess stdout.
 - stderr contains status, progress, timing, and diagnostics.
 
-In JSON mode (`--json`), stdout instead carries exactly one versioned JSON
-document — a result document on success or a diagnostic document on failure —
-with generated content embedded in `result.content`.
+In JSON mode (`--json`), a successful command writes exactly one versioned
+result document to stdout, with generated content embedded in `result.content`.
+On failure, stdout is left empty and the single versioned diagnostic document
+is written to stderr instead. Diagnostics therefore stay on stderr in both
+modes, so a caller parsing errors reads stderr regardless of `--json`.
 
 This makes redirection predictable:
 
@@ -586,9 +607,10 @@ do not print a timing summary.
 
 Use `--json` when a caller needs machine-readable command output. Every
 invocation emits exactly one versioned JSON document: a result document on
-success or a diagnostic document on failure. Generated stdout artefacts, such
-as the Ninja text from `generate`, are carried inside the successful result
-document rather than written as unstructured text.
+success, written to stdout, or a diagnostic document on failure, written to
+stderr while stdout stays empty. Generated stdout artefacts, such as the Ninja
+text from `generate`, are carried inside the successful result document rather
+than written as unstructured text.
 
 The following command deliberately selects a missing manifest:
 
@@ -598,7 +620,8 @@ The following command deliberately selects a missing manifest:
 netsuke --json --no-input --file missing.yml build
 ```
 
-The exact localized message can vary, but the envelope has this shape:
+The exact localized message can vary, but the diagnostic document written to
+stderr has this shape:
 
 <!-- tested-example: guide-json-output -->
 
diff --git a/tests/documentation_examples_e2e_tests.rs b/tests/documentation_examples_e2e_tests.rs
index c9336326..180c90c7 100644
--- a/tests/documentation_examples_e2e_tests.rs
+++ b/tests/documentation_examples_e2e_tests.rs
@@ -90,6 +90,43 @@ fn configured_default_builds_the_first_run_target() -> Result<()> {
     Ok(())
 }
 
+/// Generate Ninja for `guide-command-available-manifest` with `PATH` pointed at
+/// `bin_dir` only, isolating `command_available` from the host environment.
+fn generate_command_available_manifest(bin_dir_name: &str, stub: Option<&str>) -> Result<String> {
+    let workspace = manifest_workspace("guide-command-available-manifest")?;
+    let bin_dir = Utf8PathBuf::from_path_buf(workspace.path().join(bin_dir_name))
+        .map_err(|_| anyhow::anyhow!("bin directory should be UTF-8"))?;
+    test_fs::create_dir(bin_dir.as_std_path())?;
+    if let Some(name) = stub {
+        write_stub(&bin_dir, name, "#!/bin/sh\nexit 0\n")?;
+    }
+    let run = run_netsuke_in_with_env(
+        workspace.path(),
+        &["--progress", "never", "generate"],
+        &[("PATH", bin_dir.as_str())],
+    )?;
+    assert_success(&run, "guide-command-available-manifest generate")?;
+    Ok(run.stdout)
+}
+
+#[test]
+fn command_available_selects_the_documented_action_branch() -> Result<()> {
+    // With `cargo-nextest` resolvable, the first action's `when` wins.
+    let present = generate_command_available_manifest("bin", Some("cargo-nextest"))?;
+    ensure!(
+        present.contains("cargo nextest run") && !present.contains("command = cargo test"),
+        "cargo-nextest available should select the nextest branch; got:\n{present}"
+    );
+
+    // With `cargo-nextest` absent, the complementary fallback action wins.
+    let absent = generate_command_available_manifest("empty-bin", None)?;
+    ensure!(
+        absent.contains("cargo test") && !absent.contains("cargo nextest run"),
+        "cargo-nextest absent should select the fallback branch; got:\n{absent}"
+    );
+    Ok(())
+}
+
 #[test]
 fn photo_edit_example_produces_declared_jpegs_and_gallery() -> Result<()> {
     let Ok(workspace) = ninja_integration_workspace() else {