Prevent resumed slash commands from dropping release-critical arguments

The release harness advertised resumed slash commands like /export <file> and /clear --confirm, but argv parsing split every slash-prefixed token into a new command. That made the claw binary reject legitimate resumed command sequences and quietly miss the caller-provided export target.

This change teaches --resume parsing to keep command arguments attached, including absolute export paths, and locks the behavior with both parser regressions and a binary-level smoke test that exercises the real claw resume path.

Constraint: Keep the scope to a high-confidence release-path fix that fits a ~1 hour hardening pass

Rejected: Broad REPL or network end-to-end coverage expansion | too slow and too wide for the release-confidence target

Confidence: high

Scope-risk: narrow

Reversibility: clean

Directive: If new resume-supported commands accept slash-prefixed literals, extend the resume parser heuristics and add binary coverage for them

Tested: cargo test --workspace; cargo test -p rusty-claude-cli --test resume_slash_commands; cargo test -p rusty-claude-cli parses_resume_flag_with_absolute_export_path -- --exact

Not-tested: cargo clippy --workspace --all-targets -- -D warnings currently fails on pre-existing runtime/conversation/session lints outside this change

rust/crates/rusty-claude-cli/tests/resume_slash_commands.rs

@@ -0,0 +1,71 @@
+use std::fs;
+use std::path::PathBuf;
+use std::process::Command;
+use std::sync::atomic::{AtomicU64, Ordering};
+use std::time::{SystemTime, UNIX_EPOCH};
+
+use runtime::Session;
+
+static TEMP_COUNTER: AtomicU64 = AtomicU64::new(0);
+
+#[test]
+fn resumed_binary_accepts_slash_commands_with_arguments() {
+    let temp_dir = unique_temp_dir("resume-slash-commands");
+    fs::create_dir_all(&temp_dir).expect("temp dir should exist");
+
+    let session_path = temp_dir.join("session.jsonl");
+    let export_path = temp_dir.join("notes.txt");
+
+    let mut session = Session::new();
+    session
+        .push_user_text("ship the slash command harness")
+        .expect("session write should succeed");
+    session
+        .save_to_path(&session_path)
+        .expect("session should persist");
+
+    let output = Command::new(env!("CARGO_BIN_EXE_claw"))
+        .current_dir(&temp_dir)
+        .args([
+            "--resume",
+            session_path.to_str().expect("utf8 path"),
+            "/export",
+            export_path.to_str().expect("utf8 path"),
+            "/clear",
+            "--confirm",
+        ])
+        .output()
+        .expect("claw should launch");
+
+    assert!(
+        output.status.success(),
+        "stdout:\n{}\n\nstderr:\n{}",
+        String::from_utf8_lossy(&output.stdout),
+        String::from_utf8_lossy(&output.stderr)
+    );
+
+    let stdout = String::from_utf8(output.stdout).expect("stdout should be utf8");
+    assert!(stdout.contains("Export"));
+    assert!(stdout.contains("wrote transcript"));
+    assert!(stdout.contains(export_path.to_str().expect("utf8 path")));
+    assert!(stdout.contains("Cleared resumed session file"));
+
+    let export = fs::read_to_string(&export_path).expect("export file should exist");
+    assert!(export.contains("# Conversation Export"));
+    assert!(export.contains("ship the slash command harness"));
+
+    let restored = Session::load_from_path(&session_path).expect("cleared session should load");
+    assert!(restored.messages.is_empty());
+}
+
+fn unique_temp_dir(label: &str) -> PathBuf {
+    let millis = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .expect("clock should be after epoch")
+        .as_millis();
+    let counter = TEMP_COUNTER.fetch_add(1, Ordering::Relaxed);
+    std::env::temp_dir().join(format!(
+        "claw-{label}-{}-{millis}-{counter}",
+        std::process::id()
+    ))
+}