refactor: cleanup pass on document embedding/retrieval

- retrieval::retrieve_relevant now shows a spinner around the query-
  embedding call and gets its own tracing span, matching every other
  model-calling phase in the pipeline (it previously ran invisibly and
  untraced)
- add progress::report() to dedupe the show_progress-gated eprintln!
  pattern shared by research.rs and retrieval.rs
- documents::push_document builds its TextSplitter once per collect_documents
  call instead of once per file, skips the char-truncation walk entirely
  when a file is already under the limit, and pulls the source-string
  branch out of the map closure
- researcher::gather_findings drops a doc_context emptiness check that
  build_doc_context already guarantees
- documents.rs tests use tempfile::tempdir() instead of a hand-rolled
  TempDir type

Verified with cargo build/test/clippy -D warnings/fmt --check.

Cargo.lock

@@ -2129,6 +2129,7 @@ dependencies = [
  "scraper",
  "serde",
  "serde_json",
+ "tempfile",
  "text-splitter",
  "tokio",
  "tracing",

Cargo.toml

@@ -27,3 +27,4 @@ tracing-subscriber = { version = "0.3.23", features = ["env-filter"] }
 
 [dev-dependencies]
 serde_json = "1"
+tempfile = "3"

src/documents.rs

@@ -1,6 +1,6 @@
 use rig::embeddings::{EmbedError, TextEmbedder};
 use std::path::{Path, PathBuf};
-use text_splitter::TextSplitter;
+use text_splitter::{Characters, TextSplitter};
 
 /// Safety valve against accidentally pointing `--doc` at a huge binary or
 /// log file — not a content limit. Real documents are chunked in full (see
@@ -40,6 +40,7 @@ impl rig::Embed for Document {
 /// (permissions, non-UTF-8) are skipped with a warning rather than failing
 /// the whole run.
 pub(crate) fn collect_documents(paths: &[PathBuf]) -> anyhow::Result<Vec<Document>> {
+    let splitter = TextSplitter::new(CHUNK_CHARS);
     let mut documents = Vec::new();
 
     for path in paths {
@@ -47,30 +48,38 @@ pub(crate) fn collect_documents(paths: &[PathBuf]) -> anyhow::Result<Vec<Documen
             for entry in std::fs::read_dir(path)? {
                 let entry = entry?;
                 if entry.file_type()?.is_file() {
-                    push_document(&entry.path(), &mut documents);
+                    push_document(&entry.path(), &splitter, &mut documents);
                 }
             }
         } else {
-            push_document(path, &mut documents);
+            push_document(path, &splitter, &mut documents);
         }
     }
 
     Ok(documents)
 }
 
-fn push_document(path: &Path, documents: &mut Vec<Document>) {
+fn push_document(path: &Path, splitter: &TextSplitter<Characters>, documents: &mut Vec<Document>) {
     match std::fs::read_to_string(path) {
-        Ok(text) => {
-            let text: String = text.chars().take(MAX_FILE_CHARS).collect();
-            let chunks: Vec<&str> = TextSplitter::new(CHUNK_CHARS).chunks(&text).collect();
+        Ok(mut text) => {
+            // Cheap upper bound on char count, so the vast majority of
+            // documents (well under the limit) skip the char-by-char walk
+            // entirely.
+            if text.len() > MAX_FILE_CHARS && text.chars().count() > MAX_FILE_CHARS {
+                text = text.chars().take(MAX_FILE_CHARS).collect();
+            }
+            let chunks: Vec<&str> = splitter.chunks(&text).collect();
             let total = chunks.len();
-
-            documents.extend(chunks.into_iter().enumerate().map(|(i, chunk)| Document {
-                source: if total > 1 {
+            let source = |i: usize| {
+                if total > 1 {
                     format!("{} (part {}/{total})", path.display(), i + 1)
                 } else {
                     path.display().to_string()
-                },
+                }
+            };
+
+            documents.extend(chunks.into_iter().enumerate().map(|(i, chunk)| Document {
+                source: source(i),
                 text: chunk.to_string(),
             }));
         }
@@ -83,40 +92,11 @@ fn push_document(path: &Path, documents: &mut Vec<Document>) {
 #[cfg(test)]
 mod tests {
     use super::*;
-
-    /// A directory unique to this test run, under the OS temp dir, cleaned
-    /// up on drop so a panic mid-test can't leave stray files behind for the
-    /// next run.
-    struct TempDir(PathBuf);
-
-    impl TempDir {
-        fn new(name: &str) -> Self {
-            let path = std::env::temp_dir().join(format!(
-                "doubleo7-test-{name}-{}-{}",
-                std::process::id(),
-                std::time::SystemTime::now()
-                    .duration_since(std::time::UNIX_EPOCH)
-                    .expect("system clock is after the epoch")
-                    .as_nanos()
-            ));
-            std::fs::create_dir_all(&path).expect("create temp dir");
-            Self(path)
-        }
-
-        fn path(&self) -> &Path {
-            &self.0
-        }
-    }
-
-    impl Drop for TempDir {
-        fn drop(&mut self) {
-            let _ = std::fs::remove_dir_all(&self.0);
-        }
-    }
+    use tempfile::tempdir;
 
     #[test]
     fn collect_documents_reads_an_explicit_file() {
-        let dir = TempDir::new("explicit-file");
+        let dir = tempdir().unwrap();
         let file = dir.path().join("notes.txt");
         std::fs::write(&file, "hello from a file").unwrap();
 
@@ -129,7 +109,7 @@ mod tests {
 
     #[test]
     fn collect_documents_reads_every_file_in_a_directory_non_recursively() {
-        let dir = TempDir::new("directory");
+        let dir = tempdir().unwrap();
         std::fs::write(dir.path().join("a.txt"), "a").unwrap();
         std::fs::write(dir.path().join("b.txt"), "b").unwrap();
         std::fs::create_dir(dir.path().join("nested")).unwrap();
@@ -150,7 +130,7 @@ mod tests {
 
     #[test]
     fn collect_documents_skips_unreadable_paths_instead_of_failing() {
-        let dir = TempDir::new("missing");
+        let dir = tempdir().unwrap();
         let missing = dir.path().join("does-not-exist.txt");
 
         assert!(collect_documents(&[missing]).unwrap().is_empty());
@@ -158,7 +138,7 @@ mod tests {
 
     #[test]
     fn collect_documents_splits_a_large_file_into_multiple_chunks() {
-        let dir = TempDir::new("large-file");
+        let dir = tempdir().unwrap();
         let file = dir.path().join("big.txt");
         // Well over CHUNK_CHARS, and with paragraph breaks so the splitter
         // has real semantic boundaries to chunk on.

src/history.rs

@@ -270,7 +270,11 @@ mod tests {
                     serde_json::json!({ "query": "test" }),
                 )],
             },
-            Message::tool_result("call-1", "call-1-name", "1. Example\n   https://example.com\n   snippet"),
+            Message::tool_result(
+                "call-1",
+                "call-1-name",
+                "1. Example\n   https://example.com\n   snippet",
+            ),
             Message::assistant("that source looks solid"),
         ];
 

src/progress.rs

@@ -69,6 +69,15 @@ impl Drop for Spinner {
     }
 }
 
+/// Prints a status line, but only when progress display is on — matching
+/// `Spinner`'s own `enabled` gate so a call site doesn't need to repeat the
+/// `if show_progress` check inline.
+pub(crate) fn report(enabled: bool, message: impl Into<String>) {
+    if enabled {
+        eprintln!("{}", message.into());
+    }
+}
+
 /// Updates the message of whatever spinner is currently running, if any.
 /// A no-op when progress display is off (no spinner was ever started, so
 /// `active()` stays empty) or between phases (the previous `Spinner` has

src/research.rs

@@ -1,5 +1,5 @@
 use crate::documents;
-use crate::progress::REJECTED_EMOJI;
+use crate::progress::{self, REJECTED_EMOJI};
 use crate::researcher::gather_findings;
 use crate::retrieval;
 use crate::review::{self, Review};
@@ -57,12 +57,13 @@ pub(crate) async fn research(
             break;
         }
 
-        if show_progress {
-            eprintln!(
+        progress::report(
+            show_progress,
+            format!(
                 "{REJECTED_EMOJI} Findings rejected — revising for round {}...",
                 round + 1
-            );
-        }
+            ),
+        );
 
         feedback = Some(review);
     }

src/researcher.rs

@@ -70,14 +70,14 @@ pub(crate) async fn gather_findings(
     };
 
     let task = match doc_context {
-        Some(context) if !context.is_empty() => format!(
+        Some(context) => format!(
             "{task}\n\n\
              Relevant excerpts from documents the user uploaded — treat these as trusted primary \
              sources alongside anything you find on the web, and cite them with the same \
              footnote scheme (their Sources entry can just be the document path shown below):\n\
              {context}"
         ),
-        _ => task,
+        None => task,
     };
 
     let spinner = Spinner::start(show_progress, format!("{RESEARCH_EMOJI} Researching..."));

src/retrieval.rs

@@ -1,6 +1,6 @@
 use crate::documents::Document;
 use crate::models::EMBEDDING_MODEL;
-use crate::progress::{EMBED_EMOJI, Spinner};
+use crate::progress::{self, EMBED_EMOJI, Spinner};
 use rig::client::EmbeddingsClient;
 use rig::providers::ollama;
 use rig::vector_store::VectorStoreIndex;
@@ -44,6 +44,7 @@ pub(crate) async fn build_index(
 
 /// Retrieves the excerpts most semantically relevant to `query` from the
 /// index, formatted for inclusion in the researcher's task.
+#[tracing::instrument(skip(index), fields(gen_ai.agent.name = "retriever"))]
 pub(crate) async fn retrieve_relevant(
     index: &DocumentIndex,
     query: &str,
@@ -54,14 +55,20 @@ pub(crate) async fn retrieve_relevant(
         .samples(TOP_N_EXCERPTS)
         .build();
 
+    let spinner = Spinner::start(
+        show_progress,
+        format!("{EMBED_EMOJI} Retrieving relevant excerpts..."),
+    );
     let results = index.top_n::<Document>(request).await?;
+    drop(spinner);
 
-    if show_progress {
-        eprintln!(
+    progress::report(
+        show_progress,
+        format!(
             "{EMBED_EMOJI} Retrieved {} relevant excerpt(s) from uploaded documents",
             results.len()
-        );
-    }
+        ),
+    );
     tracing::info!(count = results.len(), "retrieved document excerpts");
 
     Ok(results