Make compact output match the console-style command UX

Reformat /compact output for both live and resumed sessions so compaction results are reported in the same structured console style as the rest of the CLI surface. This keeps the behavior unchanged while making skipped and successful compaction runs easier to read.

Constraint: Compact output must stay faithful to the real compaction result and not imply summarization details beyond removed/kept message counts
Rejected: Expose the generated summary body directly in /compact output | too noisy for a lightweight command-response surface
Confidence: high
Scope-risk: narrow
Reversibility: clean
Directive: Keep lifecycle and maintenance command output stylistically consistent as more slash commands reach parity
Tested: cargo fmt --manifest-path ./rust/Cargo.toml --all; cargo clippy --manifest-path ./rust/Cargo.toml --workspace --all-targets -- -D warnings; cargo test --manifest-path ./rust/Cargo.toml --workspace
Not-tested: Manual terminal UX review of compact output on very large sessions

rust/crates/rusty-claude-cli/src/main.rs

@@ -12,9 +12,7 @@ use api::{
     ToolResultContentBlock,
 };
 
-use commands::{
-    handle_slash_command, render_slash_command_help, resume_supported_slash_commands, SlashCommand,
-};
+use commands::{render_slash_command_help, resume_supported_slash_commands, SlashCommand};
 use compat_harness::{extract_manifest, UpstreamPaths};
 use render::{Spinner, TerminalRenderer};
 use runtime::{
@@ -358,6 +356,24 @@ fn format_init_report(path: &Path, created: bool) -> String {
     }
 }
 
+fn format_compact_report(removed: usize, resulting_messages: usize, skipped: bool) -> String {
+    if skipped {
+        format!(
+            "Compact
+  Result           skipped
+  Reason           session below compaction threshold
+  Messages kept    {resulting_messages}"
+        )
+    } else {
+        format!(
+            "Compact
+  Result           compacted
+  Messages removed {removed}
+  Messages kept    {resulting_messages}"
+        )
+    }
+}
+
 fn parse_git_status_metadata(status: Option<&str>) -> (Option<PathBuf>, Option<String>) {
     let Some(status) = status else {
         return (None, None);
@@ -402,23 +418,20 @@ fn run_resume_command(
             message: Some(render_repl_help()),
         }),
         SlashCommand::Compact => {
-            let Some(result) = handle_slash_command(
-                "/compact",
+            let result = runtime::compact_session(
                 session,
                 CompactionConfig {
                     max_estimated_tokens: 0,
                     ..CompactionConfig::default()
                 },
-            ) else {
-                return Ok(ResumeCommandOutcome {
-                    session: session.clone(),
-                    message: None,
-                });
-            };
-            result.session.save_to_path(session_path)?;
+            );
+            let removed = result.removed_message_count;
+            let kept = result.compacted_session.messages.len();
+            let skipped = removed == 0;
+            result.compacted_session.save_to_path(session_path)?;
             Ok(ResumeCommandOutcome {
-                session: result.session,
-                message: Some(result.message),
+                session: result.compacted_session,
+                message: Some(format_compact_report(removed, kept, skipped)),
             })
         }
         SlashCommand::Clear { confirm } => {
@@ -746,6 +759,8 @@ impl LiveCli {
     fn compact(&mut self) -> Result<(), Box<dyn std::error::Error>> {
         let result = self.runtime.compact(CompactionConfig::default());
         let removed = result.removed_message_count;
+        let kept = result.compacted_session.messages.len();
+        let skipped = removed == 0;
         self.runtime = build_runtime_with_permission_mode(
             result.compacted_session,
             self.model.clone(),
@@ -753,7 +768,7 @@ impl LiveCli {
             true,
             permission_mode_label(),
         )?;
-        println!("Compacted {removed} messages.");
+        println!("{}", format_compact_report(removed, kept, skipped));
         Ok(())
     }
 }
@@ -1384,12 +1399,12 @@ fn print_help() {
 #[cfg(test)]
 mod tests {
     use super::{
-        format_cost_report, format_init_report, format_model_report, format_model_switch_report,
-        format_permissions_report, format_permissions_switch_report, format_resume_report,
-        format_status_report, normalize_permission_mode, parse_args, parse_git_status_metadata,
-        render_config_report, render_init_claude_md, render_memory_report, render_repl_help,
-        resume_supported_slash_commands, status_context, CliAction, SlashCommand, StatusUsage,
-        DEFAULT_MODEL,
+        format_compact_report, format_cost_report, format_init_report, format_model_report,
+        format_model_switch_report, format_permissions_report, format_permissions_switch_report,
+        format_resume_report, format_status_report, normalize_permission_mode, parse_args,
+        parse_git_status_metadata, render_config_report, render_init_claude_md,
+        render_memory_report, render_repl_help, resume_supported_slash_commands, status_context,
+        CliAction, SlashCommand, StatusUsage, DEFAULT_MODEL,
     };
     use runtime::{ContentBlock, ConversationMessage, MessageRole};
     use std::path::{Path, PathBuf};
@@ -1521,6 +1536,16 @@ mod tests {
         assert!(report.contains("Turns            6"));
     }
 
+    #[test]
+    fn compact_report_uses_structured_output() {
+        let compacted = format_compact_report(8, 5, false);
+        assert!(compacted.contains("Compact"));
+        assert!(compacted.contains("Result           compacted"));
+        assert!(compacted.contains("Messages removed 8"));
+        let skipped = format_compact_report(0, 3, true);
+        assert!(skipped.contains("Result           skipped"));
+    }
+
     #[test]
     fn cost_report_uses_sectioned_layout() {
         let report = format_cost_report(runtime::TokenUsage {