fix(cli): preserve trailing block separators in streamed markdown

When markdown is streamed chunk-by-chunk, block-level elements (paragraphs,
headings, code blocks, lists) need trailing newlines to prevent consecutive
chunks from running together on the same line.

This fix:
- Refactors render_markdown() to use a new render_markdown_raw() helper
- Adds markdown_to_ansi_stream() for stream-aware rendering that preserves
  trailing newlines from block elements
- Updates MarkdownStreamState::push() to use markdown_to_ansi_stream()
  instead of markdown_to_ansi()
- Adds a test verifying that streamed blocks remain visually separated

Fixes #3257

.gjc/_session-5e2dd1e8-ea4b-4af1-b56b-89ab7cca4299/runtime/runtime-state.json

@@ -0,0 +1 @@
+{"schema_version":1,"session_id":"5e2dd1e8-ea4b-4af1-b56b-89ab7cca4299","state":"running","ready_for_input":false,"updated_at":"2026-10-12T22:09:30.659Z","current_turn_id":null,"last_turn_id":null,"live":true,"reason":null,"source":"agent_session_event","event":"turn_start","cwd":"/home/bellman/Data/Workspace/gc-task-cc-issue-3257-lane","workdir":"/home/bellman/Data/Workspace/gc-task-cc-issue-3257-lane","branch":null,"session_file":"/home/bellman/.gajaeway/broker/agent/sessions/v2-6fji37qf7ld523ivvoiohlcpmz3nu45m2apxyrkusn5nxczjmouq/2026-10-12T22-04-33-362Z_5e2dd1e8-ea4b-4af1-b56b-89ab7cca4299.jsonl","activity":{"seq":115,"last_activity_at":"2026-10-12T22:09:34.144Z","tool":"bash","phase":"started","outcome":null,"elapsed_ms":null,"active_tool_count":1,"active_tools":[{"tool":"bash","started_at":"2026-10-12T22:09:34.144Z"}],"in_flight":[{"digest":"e603a70efb03b6b2b78c94b704197d26fc8a35113543291a21f68b3b08ca11a9","tool":"bash","started_at":"2026-10-12T22:09:34.144Z"}]}}

.gjc/_session-5e2dd1e8-ea4b-4af1-b56b-89ab7cca4299/runtime/runtime-state.json.lock

@@ -0,0 +1 @@
+{"pid":1,"start_time":"unknown","token":"1a2e8a33-76f2-4175-ac23-1521458f12a2","owner_host_id":"7af2fb0e8e37bd543e3d0bda6f205b56f30077b5a9b77e83208e94ae441315ac","released":true}

.gjc/_session-5e2dd1e8-ea4b-4af1-b56b-89ab7cca4299/runtime/runtime-state.json.lock.transition.owner

@@ -0,0 +1 @@
+{"pid":1,"start_time":"unknown","token":"a1342032-af80-4a49-a783-291bf73bf027","owner_host_id":"7af2fb0e8e37bd543e3d0bda6f205b56f30077b5a9b77e83208e94ae441315ac","released":true}

.gjc/state/sdk/5e2dd1e8-ea4b-4af1-b56b-89ab7cca4299.json

@@ -0,0 +1,12 @@
+{
+  "version": 1,
+  "sessionId": "5e2dd1e8-ea4b-4af1-b56b-89ab7cca4299",
+  "pid": 487360,
+  "host": "127.0.0.1",
+  "port": 37541,
+  "url": "ws://127.0.0.1:37541",
+  "token": "LlIfu_aHH57jfys2Ii0ORMrnu56NLAa1",
+  "startedAt": 1791842673967,
+  "updatedAt": 1791842673967,
+  "stale": false
+}

.gjc/state/sdk/5e2dd1e8-ea4b-4af1-b56b-89ab7cca4299.lifecycle.json

@@ -0,0 +1 @@
+{"effectMarker":"f441857a-f591-474b-b34a-6d89b2bf9feb","incarnation":"linux:159099652","pid":487360}

.gjc/state/sdk/5e2dd1e8-ea4b-4af1-b56b-89ab7cca4299.lifecycle.ready.json

@@ -0,0 +1 @@
+{"effectMarker":"f441857a-f591-474b-b34a-6d89b2bf9feb","incarnation":"linux:159099652","pid":487360}

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

@@ -249,6 +249,16 @@ impl TerminalRenderer {
 
     #[must_use]
     pub fn render_markdown(&self, markdown: &str) -> String {
+        self.render_markdown_raw(markdown).trim_end().to_string()
+    }
+
+    /// Render markdown to ANSI without trimming trailing whitespace.
+    ///
+    /// Block-level events (paragraphs, headings, lists, code blocks) emit their
+    /// trailing newline separators here. `render_markdown` trims them for
+    /// one-shot output, while streaming keeps them so that successive chunks
+    /// stay on their own lines instead of running together.
+    fn render_markdown_raw(&self, markdown: &str) -> String {
         let normalized = normalize_nested_fences(markdown);
         let mut output = String::new();
         let mut state = RenderState::default();
@@ -267,7 +277,7 @@ impl TerminalRenderer {
             );
         }
 
-        output.trim_end().to_string()
+        output
     }
 
     #[must_use]
@@ -275,6 +285,18 @@ impl TerminalRenderer {
         self.render_markdown(markdown)
     }
 
+    /// Stream-friendly variant of `markdown_to_ansi` that preserves trailing
+    /// block separators (such as a paragraph's closing newlines).
+    ///
+    /// `MarkdownStreamState::push` writes each rendered chunk directly to the
+    /// terminal with no separator of its own, so the trailing newlines must
+    /// survive here to keep a paragraph from sticking to the block that follows
+    /// it. The final `flush` still uses `markdown_to_ansi` to trim the tail.
+    #[must_use]
+    pub fn markdown_to_ansi_stream(&self, markdown: &str) -> String {
+        self.render_markdown_raw(markdown)
+    }
+
     #[allow(clippy::too_many_lines)]
     fn render_event(
         &self,
@@ -609,7 +631,7 @@ impl MarkdownStreamState {
         let split = find_stream_safe_boundary(&self.pending)?;
         let ready = self.pending[..split].to_string();
         self.pending.drain(..split);
-        Some(renderer.markdown_to_ansi(&ready))
+        Some(renderer.markdown_to_ansi_stream(&ready))
     }
 
     #[must_use]
@@ -1052,6 +1074,34 @@ mod tests {
         assert!(plain_text.contains("fn nested()"));
     }
 
+    #[test]
+    fn stream_rendering_preserves_block_separators() {
+        let renderer = TerminalRenderer::new();
+
+        // The stream variant keeps the paragraph-ending newlines that the
+        // one-shot variant trims, so consecutive streamed chunks do not run
+        // into each other when written back-to-back to the terminal.
+        let streamed = renderer.markdown_to_ansi_stream("Intro paragraph.\n\n");
+        assert!(streamed.ends_with('\n'));
+        assert!(!renderer
+            .markdown_to_ansi("Intro paragraph.\n\n")
+            .ends_with('\n'));
+
+        let mut state = MarkdownStreamState::default();
+        let first = state
+            .push(&renderer, "Intro paragraph.\n\n")
+            .expect("blank line closes the paragraph block");
+        let second = state
+            .push(&renderer, "1. first item\n\n")
+            .expect("blank line closes the list block");
+
+        let combined = strip_ansi(&format!("{first}{second}"));
+        assert!(combined.contains("Intro paragraph."));
+        assert!(combined.contains("1. first item"));
+        // The two blocks stay on separate lines instead of sticking together.
+        assert!(!combined.contains("Intro paragraph.1."));
+    }
+
     #[test]
     fn spinner_advances_frames() {
         let terminal_renderer = TerminalRenderer::new();