add test-conversation tool for debugging transcript parsing

Standalone binary that exercises TailMessages on a transcript file,
reporting progress and timing. Useful for isolating conversation
resolution issues from the full hook pipeline.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

poc-memory/src/bin/test-conversation.rs

@@ -0,0 +1,65 @@
+// Test tool for the conversation resolver.
+// Usage: POC_SESSION_ID=<id> cargo run --bin test-conversation
+//    or: cargo run --bin test-conversation -- <transcript-path>
+
+use std::time::Instant;
+
+fn main() {
+    let path = std::env::args().nth(1).unwrap_or_else(|| {
+        let session_id = std::env::var("POC_SESSION_ID")
+            .expect("pass a transcript path or set POC_SESSION_ID");
+        let projects = poc_memory::config::get().projects_dir.clone();
+        eprintln!("session: {}", session_id);
+        eprintln!("projects dir: {}", projects.display());
+
+        let mut found = None;
+        if let Ok(dirs) = std::fs::read_dir(&projects) {
+            for dir in dirs.filter_map(|e| e.ok()) {
+                let path = dir.path().join(format!("{}.jsonl", session_id));
+                eprintln!("  checking: {}", path.display());
+                if path.exists() {
+                    found = Some(path);
+                    break;
+                }
+            }
+        }
+        let path = found.expect("transcript not found");
+        path.to_string_lossy().to_string()
+    });
+
+    let meta = std::fs::metadata(&path).expect("can't stat file");
+    eprintln!("transcript: {} ({} bytes)", path, meta.len());
+
+    let t0 = Instant::now();
+    let iter = poc_memory::transcript::TailMessages::open(&path)
+        .expect("can't open transcript");
+
+    let mut count = 0;
+    let mut total_bytes = 0;
+    let mut last_report = Instant::now();
+
+    for (role, content, ts) in iter {
+        count += 1;
+        total_bytes += content.len();
+
+        if last_report.elapsed().as_secs() >= 2 {
+            eprintln!("  ... {} messages, {}KB so far ({:.1}s)",
+                count, total_bytes / 1024, t0.elapsed().as_secs_f64());
+            last_report = Instant::now();
+        }
+
+        if count <= 5 {
+            let preview: String = content.chars().take(80).collect();
+            eprintln!("  [{}] {} {}: {}...",
+                count, &ts[..ts.len().min(19)], role, preview);
+        }
+
+        if total_bytes >= 200_000 {
+            eprintln!("  hit 200KB budget at {} messages", count);
+            break;
+        }
+    }
+
+    let elapsed = t0.elapsed();
+    eprintln!("done: {} messages, {}KB in {:.3}s", count, total_bytes / 1024, elapsed.as_secs_f64());
+}