diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1dc703d..e0569e8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+- The CLI prints one GitHub star line to stderr after the fifth successful interactive run, once ever (counter in the cache directory). It is silent for the MCP server, with `--json`, in CI, and when stderr is not a terminal; `LOCKDOCS_NO_STAR_HINT=1` turns it off.
+
 ## 0.3.0
 
 - **Docs sites follow your major.** For packages whose docs live in a separate website repository, `lockdocs fetch` takes the docs for the pinned major: the default branch when your major is the latest, a `vN` / `N.x` branch when the site keeps one (Tailwind CSS v3, Prisma v6), or the last commit before the next major was released. Pages about a later major are skipped. React keeps the latest-only rule (react.dev documents APIs before they ship). tokio's website (tutorial and topics) is added, and docs sites now work for crates and PyPI packages too.
diff --git a/crates/lockdocs/src/main.rs b/crates/lockdocs/src/main.rs
index 41ef232..57f96a9 100644
--- a/crates/lockdocs/src/main.rs
+++ b/crates/lockdocs/src/main.rs
@@ -1,5 +1,6 @@
 mod mcp;
 mod setup;
+mod star_hint;
 mod tools;
 
 use anyhow::{bail, Result};
@@ -151,7 +152,12 @@ fn run() -> Result<()> {
     }
     let json = args.on("json");
     let engine = || Engine::new(&args.root(), args.opts());
-    match cmd.as_str() {
+    let counts_as_run = !json
+        && !matches!(
+            cmd.as_str(),
+            "mcp" | "serve" | "help" | "--help" | "-h" | "version" | "--version" | "-V" | "setup" | "cache" | "fetch" | "pull"
+        );
+    let result = match cmd.as_str() {
         "mcp" | "serve" => {
             let offline = args.on("offline");
             // Fetch the model in the background; queries are keyword-only until it lands.
@@ -207,7 +213,11 @@ fn run() -> Result<()> {
                 Err(err) => bail!("{err}"),
             }
         }
+    };
+    if result.is_ok() && counts_as_run {
+        star_hint::after_success();
     }
+    result
 }
 
 fn ensure_model(offline: bool) {
diff --git a/crates/lockdocs/src/star_hint.rs b/crates/lockdocs/src/star_hint.rs
new file mode 100644
index 0000000..575a2b3
--- /dev/null
+++ b/crates/lockdocs/src/star_hint.rs
@@ -0,0 +1,134 @@
+//! A one-time star line on stderr after the fifth successful CLI run.
+//!
+//! The run counter lives in the lockdocs cache directory (`LOCKDOCS_CACHE`). The line is shown once
+//! ever, and never for the MCP server, for a non-TTY stderr, in CI, or when
+//! `LOCKDOCS_NO_STAR_HINT` is set.
+
+use std::io::IsTerminal;
+use std::path::{Path, PathBuf};
+
+pub const OPT_OUT_ENV: &str = "LOCKDOCS_NO_STAR_HINT";
+const FILE_NAME: &str = "star-hint";
+const SHOWN: &str = "shown";
+const SHOW_AFTER_RUNS: u32 = 5;
+const MESSAGE: &str = "Enjoying lockdocs? A GitHub star helps others find it: https://github.com/SylphxAI/lockdocs";
+
+/// What the environment says about where the run is happening.
+pub struct Context {
+    pub stderr_is_tty: bool,
+    pub ci: bool,
+    pub opted_out: bool,
+}
+
+impl Context {
+    fn from_process() -> Self {
+        let set = |key: &str| std::env::var_os(key).is_some_and(|v| !v.is_empty());
+        Context {
+            stderr_is_tty: std::io::stderr().is_terminal(),
+            ci: set("CI"),
+            opted_out: set(OPT_OUT_ENV),
+        }
+    }
+
+    fn quiet(&self) -> bool {
+        !self.stderr_is_tty || self.ci || self.opted_out
+    }
+}
+
+/// Decide from the stored counter text. Returns the text to store next and
+/// whether to print the line now.
+pub fn step(stored: Option<&str>, context: &Context) -> (Option<String>, bool) {
+    if context.quiet() {
+        return (None, false);
+    }
+    let stored = stored.map(str::trim).unwrap_or("");
+    if stored == SHOWN {
+        return (None, false);
+    }
+    let runs = stored.parse::<u32>().unwrap_or(0).saturating_add(1);
+    if runs >= SHOW_AFTER_RUNS {
+        (Some(SHOWN.to_string()), true)
+    } else {
+        (Some(runs.to_string()), false)
+    }
+}
+
+fn state_path() -> PathBuf {
+    lockdocs_core::cache::dir().join(FILE_NAME)
+}
+
+fn apply(path: &Path, context: &Context) -> bool {
+    let stored = std::fs::read_to_string(path).ok();
+    let (next, show) = step(stored.as_deref(), context);
+    if let Some(next) = next {
+        if let Some(parent) = path.parent() {
+            let _ = std::fs::create_dir_all(parent);
+        }
+        if std::fs::write(path, next).is_err() {
+            return false;
+        }
+    }
+    show
+}
+
+/// Call after a CLI run that succeeded. Best effort: any file error is silent.
+pub fn after_success() {
+    let context = Context::from_process();
+    if context.quiet() {
+        return;
+    }
+    if apply(&state_path(), &context) {
+        eprintln!("{MESSAGE}");
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn context(stderr_is_tty: bool, ci: bool, opted_out: bool) -> Context {
+        Context { stderr_is_tty, ci, opted_out }
+    }
+
+    #[test]
+    fn counts_four_runs_then_shows_once() {
+        let interactive = context(true, false, false);
+        let mut stored: Option<String> = None;
+        for run in 1..=4 {
+            let (next, show) = step(stored.as_deref(), &interactive);
+            assert!(!show, "run {run}");
+            stored = next;
+        }
+        assert_eq!(stored.as_deref(), Some("4"));
+        let (next, show) = step(stored.as_deref(), &interactive);
+        assert!(show);
+        assert_eq!(next.as_deref(), Some("shown"));
+        let (next, show) = step(next.as_deref(), &interactive);
+        assert!(!show);
+        assert_eq!(next, None);
+    }
+
+    #[test]
+    fn stays_silent_and_uncounted_when_gated() {
+        for quiet in [context(false, false, false), context(true, true, false), context(true, false, true)] {
+            assert_eq!(step(Some("4"), &quiet), (None, false));
+        }
+    }
+
+    #[test]
+    fn garbage_counter_restarts() {
+        let interactive = context(true, false, false);
+        assert_eq!(step(Some("x"), &interactive), (Some("1".into()), false));
+    }
+
+    #[test]
+    fn persists_and_shows_on_the_fifth_run_only() {
+        let dir = std::env::temp_dir().join(format!("lockdocs-star-hint-{}", std::process::id()));
+        let path = dir.join("nested").join(FILE_NAME);
+        let interactive = context(true, false, false);
+        let shown: Vec<bool> = (0..7).map(|_| apply(&path, &interactive)).collect();
+        assert_eq!(shown, [false, false, false, false, true, false, false]);
+        assert_eq!(std::fs::read_to_string(&path).unwrap(), "shown");
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+}
diff --git a/docs/guide/setup.md b/docs/guide/setup.md
index 80453af..0d8f137 100644
--- a/docs/guide/setup.md
+++ b/docs/guide/setup.md
@@ -21,4 +21,5 @@
 | `LOCKDOCS_ROOT` | Project directory when the client sends no roots |
 | `LOCKDOCS_FETCH=1` | Allow [fetching](./fetch) exact versions that are not installed |
 | `LOCKDOCS_CACHE` | Cache directory (default: the OS cache dir + `/lockdocs`) |
+| `LOCKDOCS_NO_STAR_HINT=1` | Turn off the one-time GitHub star line the CLI prints to stderr after the fifth successful interactive run (never shown for the MCP server, with `--json`, in CI, or when stderr is not a terminal) |
 | `LOCKDOCS_NO_SYSTEM_PYTHON=1` | Do not ask the system interpreter for its site-packages |