fix: use Native structured output for reviewer instead of forced tool call

Ollama doesn't support tool_choice, so rig's tool-forced extractor
(client.extractor::<Review>()) never actually compelled the reviewer's
small local model to call the submit tool -- it just answered in prose,
and extraction exhausted its retries with "No data extracted" every time.

Switch to rig's typed-prompt API (agent.prompt_typed::<Review>()), which
uses Native output mode: Ollama's own `format` JSON-schema constraint on
the completion request, honored regardless of tool-calling ability.
Verified against a live local Ollama instance.

src/research.rs

@@ -27,20 +27,17 @@ pub(crate) async fn research(topic: &str, show_progress: bool) -> anyhow::Result
         findings = gathered.findings;
         incomplete = gathered.incomplete;
 
-        // The researcher ran out of turns mid-investigation rather than
+        // Prevent repeat iterations where researcher hits same dead end.
-        // concluding on its own — another round would just repeat the same
-        // dead end, so stop and write up whatever was gathered.
         if incomplete {
             tracing::info!(round, "researcher exhausted its turn budget");
             break;
         }
 
         let review = review::review_findings(&client, topic, &findings, show_progress).await?;
-        let approved = review.approved;
 
-        tracing::info!(round, approved, "review verdict");
+        tracing::info!(round, review.approved, "review verdict");
 
-        if approved || round == MAX_RESEARCH_ROUNDS {
+        if review.approved || round == MAX_RESEARCH_ROUNDS {
             break;
         }
 

src/review.rs

@@ -1,4 +1,5 @@
 use rig::client::AgentClientExt;
+use rig::completion::TypedPrompt;
 use rig::providers::ollama;
 use rig::schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
@@ -25,10 +26,18 @@ pub(crate) struct Review {
     pub(crate) gaps: String,
 }
 
-/// Uses rig's typed extractor — a forced tool call into a `submit(Review)`
+/// Retries for a review that fails to come back as valid structured output
-/// schema — rather than parsing free-text output, so the verdict and its
+/// (e.g. a transient network error), on top of the initial attempt.
-/// two feedback fields always come back structured instead of relying on
+const REVIEW_RETRIES: usize = 2;
-/// scanning prose for a trailing yes/no.
+
+/// Uses rig's typed-prompt API — `Native` structured output constraining the
+/// model's own reply to the `Review` schema — rather than a forced tool call
+/// or parsing free-text output. A forced tool call needs `tool_choice`
+/// support, which Ollama doesn't have: the reviewer's small local model would
+/// just answer in prose and never call the tool, so extraction only ever
+/// exhausted its retries and errored out. `Native` mode instead uses Ollama's
+/// own `format` JSON-schema constraint, which is honored regardless of
+/// tool-calling ability.
 #[tracing::instrument(skip(client, findings), fields(gen_ai.agent.name = "reviewer"))]
 pub(crate) async fn review_findings(
     client: &ollama::Client,
@@ -37,7 +46,7 @@ pub(crate) async fn review_findings(
     show_progress: bool,
 ) -> anyhow::Result<Review> {
     let reviewer = client
-        .extractor::<Review>(REVIEWER_MODEL)
+        .agent(REVIEWER_MODEL)
         .preamble(
             "You are a skeptical fact-checker reviewing another researcher's notes before they \
              get turned into a report. Approve only if every conclusion in the findings is \
@@ -47,20 +56,40 @@ pub(crate) async fn review_findings(
              Always separate the solid, well-supported findings from the gaps so a follow-up \
              research pass knows what to keep and what to dig into further.",
         )
-        .retries(2)
         .build();
 
     let spinner = Spinner::start(
         show_progress,
         format!("{REVIEW_EMOJI} Reviewing findings..."),
     );
-    let review = reviewer
+    let prompt = format!("Topic: {topic}\n\nResearch findings to review:\n{findings}");
-        .extract(format!(
+
-            "Topic: {topic}\n\nResearch findings to review:\n{findings}"
+    let mut last_error = None;
-        ))
+    let mut review = None;
-        .await?;
+    for attempt in 0..=REVIEW_RETRIES {
+        match reviewer.prompt_typed::<Review>(prompt.clone()).await {
+            Ok(r) => {
+                review = Some(r);
+                break;
+            }
+            Err(e) => {
+                let suffix = if attempt < REVIEW_RETRIES {
+                    " Retrying..."
+                } else {
+                    ""
+                };
+                tracing::warn!("Attempt {attempt} to extract JSON failed: {e:?}.{suffix}");
+                last_error = Some(e);
+            }
+        }
+    }
     drop(spinner);
 
+    let review = match review {
+        Some(review) => review,
+        None => return Err(last_error.expect("loop always sets last_error on failure").into()),
+    };
+
     tracing::info!(approved = review.approved, gaps = %review.gaps, "review complete");
 
     Ok(review)

src/tools.rs

@@ -44,6 +44,7 @@ pub(crate) async fn search_web(
 ) -> Result<String, ToolExecutionError> {
     progress::set_activity(format!("{SEARCH_EMOJI} Searching: {query}"));
 
+    // TODO re-use same client object?
     let response = reqwest::Client::new()
         .get(format!("{}/search", searxng_base_url()))
         .query(&[("q", query.as_str()), ("format", "json")])