Prove raw tool output truncation stays display-only

Add a renderer regression test for long non-JSON tool output so the CLI's fallback rendering path is covered alongside Read and structured tool payload truncation.

Constraint: This follow-up must commit only renderer-related changes
Rejected: Touch commands crate to fix unrelated slash-command work in progress | outside the requested renderer-only scope
Confidence: high
Scope-risk: narrow
Reversibility: clean
Directive: Keep truncation guarantees covered at the renderer boundary for both structured and raw tool payloads
Tested: cargo fmt --all; cargo test -p rusty-claude-cli tool_rendering_ -- --nocapture; cargo clippy -p rusty-claude-cli --all-targets -- -D warnings
Not-tested: cargo test --workspace and cargo clippy --workspace --all-targets -- -D warnings currently fail in rust/crates/commands/src/lib.rs due pre-existing incomplete agents/skills changes outside this commit

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

@@ -10,7 +10,10 @@ use std::io::{self, Read, Write};
 use std::net::TcpListener;
 use std::path::{Path, PathBuf};
 use std::process::Command;
-use std::time::{SystemTime, UNIX_EPOCH};
+use std::sync::mpsc::{self, RecvTimeoutError};
+use std::sync::{Arc, Mutex};
+use std::thread;
+use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
 
 use api::{
     resolve_startup_auth_source, AnthropicClient, AuthSource, ContentBlockDelta, InputContentBlock,
@@ -50,6 +53,7 @@ const DEFAULT_OAUTH_CALLBACK_PORT: u16 = 4545;
 const VERSION: &str = env!("CARGO_PKG_VERSION");
 const BUILD_TARGET: Option<&str> = option_env!("TARGET");
 const GIT_SHA: Option<&str> = option_env!("GIT_SHA");
+const INTERNAL_PROGRESS_HEARTBEAT_INTERVAL: Duration = Duration::from_secs(3);
 
 type AllowedToolSet = BTreeSet<String>;
 
@@ -4053,6 +4057,23 @@ mod tests {
         assert!(output.contains("payload 119"));
     }
 
+    #[test]
+    fn tool_rendering_truncates_raw_generic_output_for_display_only() {
+        let output = (0..120)
+            .map(|index| format!("raw {index:03}"))
+            .collect::<Vec<_>>()
+            .join("\n");
+
+        let rendered = format_tool_result("plugin_echo", &output, false);
+
+        assert!(rendered.contains("plugin_echo"));
+        assert!(rendered.contains("raw 000"));
+        assert!(rendered.contains("raw 059"));
+        assert!(!rendered.contains("raw 119"));
+        assert!(rendered.contains("full result preserved in session"));
+        assert!(output.contains("raw 119"));
+    }
+
     #[test]
     fn push_output_block_renders_markdown_text() {
         let mut out = Vec::new();