feat: add doctor command for diagnosing installs and cleaning stale daemon state (#1254)

* feat: add `doctor` command for install diagnostics and cleanup

Adds `agent-browser doctor`, a one-shot diagnostic that checks
environment, Chrome install, daemon state, config, encryption key,
providers, network reachability, and a live headless launch test.
Auto-cleans stale `.sock` / `.pid` / `.version` / `.stream` sidecar
files on every run. Destructive repairs (reinstall Chrome, purge old
state, close version-mismatched daemons, generate missing encryption
key) are gated behind `--fix`. Supports `--offline`, `--quick`, and
`--json`.

* fixes

cli/src/doctor/environment.rs

@@ -0,0 +1,140 @@
+//! Check the local environment: CLI version, platform, state/socket dirs,
+//! and free disk space.
+
+use std::path::Path;
+
+use super::helpers::{disk_free_bytes, human_size, is_writable_dir};
+use super::{Check, Status};
+use crate::connection::get_socket_dir;
+use crate::native::state::get_state_dir;
+
+pub(super) fn check(checks: &mut Vec<Check>) {
+    let category = "Environment";
+
+    let version = env!("CARGO_PKG_VERSION");
+    let platform = format!("{} {}", std::env::consts::OS, std::env::consts::ARCH);
+    checks.push(Check::new(
+        "env.version",
+        category,
+        Status::Pass,
+        format!("CLI version {} ({})", version, platform),
+    ));
+
+    match dirs::home_dir() {
+        Some(home) => checks.push(Check::new(
+            "env.home",
+            category,
+            Status::Pass,
+            format!("Home directory {}", home.display()),
+        )),
+        None => checks.push(Check::new(
+            "env.home",
+            category,
+            Status::Fail,
+            "Could not determine home directory",
+        )),
+    }
+
+    let state_dir = get_state_dir();
+    let socket_dir = get_socket_dir();
+
+    // Under the default setup, state and socket dirs are the same
+    // (~/.agent-browser). Collapse to a single line when they match;
+    // split when XDG_RUNTIME_DIR or AGENT_BROWSER_SOCKET_DIR diverts
+    // sockets elsewhere.
+    if state_dir == socket_dir {
+        push_dir_check(
+            checks,
+            "env.state_dir",
+            category,
+            "State and socket directory",
+            &state_dir,
+        );
+    } else {
+        push_dir_check(
+            checks,
+            "env.state_dir",
+            category,
+            "State directory",
+            &state_dir,
+        );
+        push_dir_check(
+            checks,
+            "env.socket_dir",
+            category,
+            "Socket directory",
+            &socket_dir,
+        );
+    }
+
+    match disk_free_bytes(&state_dir) {
+        Some(bytes) => {
+            let mb = bytes / (1024 * 1024);
+            let human = human_size(bytes);
+            if mb < 500 {
+                checks.push(
+                    Check::new(
+                        "env.disk_free",
+                        category,
+                        Status::Warn,
+                        format!("Low disk space at state dir: {} free", human),
+                    )
+                    .with_fix("free up disk space; Chrome installs require ~500 MB"),
+                );
+            } else {
+                checks.push(Check::new(
+                    "env.disk_free",
+                    category,
+                    Status::Pass,
+                    format!("{} free at state dir", human),
+                ));
+            }
+        }
+        None => checks.push(Check::new(
+            "env.disk_free",
+            category,
+            Status::Info,
+            "Disk free check unavailable on this platform",
+        )),
+    }
+}
+
+fn push_dir_check(
+    checks: &mut Vec<Check>,
+    id: &'static str,
+    category: &'static str,
+    label: &str,
+    dir: &Path,
+) {
+    if dir.exists() {
+        if is_writable_dir(dir) {
+            checks.push(Check::new(
+                id,
+                category,
+                Status::Pass,
+                format!("{} {}", label, dir.display()),
+            ));
+        } else {
+            checks.push(
+                Check::new(
+                    id,
+                    category,
+                    Status::Fail,
+                    format!("{} not writable: {}", label, dir.display()),
+                )
+                .with_fix(format!("chmod u+rwx {}", dir.display())),
+            );
+        }
+    } else {
+        checks.push(Check::new(
+            id,
+            category,
+            Status::Info,
+            format!(
+                "{} does not exist yet (will be created on first use): {}",
+                label,
+                dir.display()
+            ),
+        ));
+    }
+}