feat: 9 quality improvements — multi-model routing, incremental reviews, structured logging, tests

- Fix panic-prone unwrap() calls in production paths (adapters, verification)
- Add 82 new tests: API layer (36), database layer (27), state (2), config (4), incremental SHA (2), and more
- GitHub suggestion blocks: multi-line support with start_line/line for one-click PR fixes
- Incremental review: push-by-push delta using last_reviewed_shas and compare API
- Multi-model routing: ModelRole::Fast cascades model_fast → model_weak → primary
- Wire up dead code: InteractiveCommand → webhook, storage → API, model_name → pipeline, detect_context_window → doctor
- Remove unused Plugin trait, legacy Ollama types
- Replace all eprintln!/println! with tracing::error!/warn!/info! in server modules
- Add delete_review and prune_reviews API endpoints
- Reduce cloning by inlining OllamaShowRequest/Response

Closes #8, #16, #26

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: haasonsaas

src/adapters/llm.rs

@@ -65,7 +65,6 @@ pub struct Usage {
 #[async_trait]
 pub trait LLMAdapter: Send + Sync {
     async fn complete(&self, request: LLMRequest) -> Result<LLMResponse>;
-    #[allow(dead_code)]
     fn model_name(&self) -> &str;
 }
 
@@ -99,9 +98,8 @@ pub fn create_adapter(config: &ModelConfig) -> Result<Box<dyn LLMAdapter>> {
     }
 
     // Vendor-prefixed model IDs (vendor/model)
-    if config.model_name.contains('/') {
-        let (vendor, model) = config.model_name.split_once('/').unwrap();
-        let model = model.to_string();
+    if let Some((vendor, model_suffix)) = config.model_name.split_once('/') {
+        let model = model_suffix.to_string();
         match vendor {
             "anthropic" => {
                 // Route anthropic/ prefix directly to the Anthropic adapter

src/adapters/ollama.rs

@@ -43,57 +43,7 @@ struct OllamaChatResponse {
     eval_count: Option<usize>,
 }
 
-// -- Legacy generate API types (kept for reference / future use) --
-
-#[allow(dead_code)]
-#[derive(Serialize)]
-struct OllamaGenerateRequest {
-    model: String,
-    prompt: String,
-    system: String,
-    temperature: f32,
-    num_predict: usize,
-    stream: bool,
-}
-
-#[allow(dead_code)]
-#[derive(Deserialize)]
-struct OllamaGenerateResponse {
-    response: String,
-    model: String,
-    done: bool,
-    _context: Option<Vec<i32>>,
-    _total_duration: Option<u64>,
-    prompt_eval_count: Option<usize>,
-    eval_count: Option<usize>,
-}
-
 // -- /api/show types for context window detection --
-
-#[allow(dead_code)]
-#[derive(Serialize)]
-struct OllamaShowRequest {
-    name: String,
-}
-
-#[allow(dead_code)]
-#[derive(Deserialize)]
-struct OllamaShowResponse {
-    #[serde(default)]
-    parameters: Option<String>,
-    #[allow(dead_code)]
-    #[serde(default)]
-    details: Option<OllamaShowDetails>,
-}
-
-#[allow(dead_code)]
-#[derive(Deserialize)]
-struct OllamaShowDetails {
-    family: Option<String>,
-    parameter_size: Option<String>,
-    quantization_level: Option<String>,
-}
-
 impl OllamaAdapter {
     pub fn new(config: ModelConfig) -> Result<Self> {
         let base_url = config
@@ -131,27 +81,20 @@ impl OllamaAdapter {
     ///
     /// Returns `Some(num_ctx)` if the model metadata contains a `num_ctx` parameter,
     /// or `None` if the endpoint is unreachable or the parameter is not found.
-    #[allow(dead_code)]
+    #[allow(dead_code)] // Public API, used in tests; production uses OfflineModelManager
     pub async fn detect_context_window(&self) -> Option<usize> {
         let url = format!("{}/api/show", self.base_url);
-        let show_request = OllamaShowRequest {
-            name: self.model_name_bare().to_string(),
-        };
+        let body = serde_json::json!({"name": self.model_name_bare()});
 
-        let response = self
-            .client
-            .post(&url)
-            .json(&show_request)
-            .send()
-            .await
-            .ok()?;
+        let response = self.client.post(&url).json(&body).send().await.ok()?;
 
         if !response.status().is_success() {
             return None;
         }
 
-        let show_response: OllamaShowResponse = response.json().await.ok()?;
-        parse_num_ctx(show_response.parameters.as_deref())
+        let value: serde_json::Value = response.json().await.ok()?;
+        let parameters = value.get("parameters").and_then(|p| p.as_str());
+        parse_num_ctx(parameters)
     }
 }
 
@@ -162,8 +105,8 @@ impl OllamaAdapter {
 /// num_ctx 4096
 /// temperature 0.8
 /// ```
-#[allow(dead_code)]
-fn parse_num_ctx(parameters: Option<&str>) -> Option<usize> {
+#[allow(dead_code)] // Called by detect_context_window
+pub(crate) fn parse_num_ctx(parameters: Option<&str>) -> Option<usize> {
     let params = parameters?;
     for line in params.lines() {
         let line = line.trim();

src/commands/doctor.rs

@@ -131,9 +131,7 @@ pub async fn doctor_command(config: Config) -> Result<()> {
 
             // Context window detection (Ollama only)
             if endpoint_type == "ollama" {
-                if let Some(ctx_size) =
-                    detect_model_context_window(&client, &base_url, &recommended.name).await
-                {
+                if let Ok(Some(ctx_size)) = manager.detect_context_window(&recommended.name).await {
                     println!(
                         "  Context window: {} tokens (detected from model)",
                         ctx_size
@@ -289,50 +287,6 @@ fn estimate_tokens(text: &str) -> usize {
     (text.len() / 4).max(1)
 }
 
-/// Query Ollama's `/api/show` to detect the model's context window size.
-async fn detect_model_context_window(
-    client: &Client,
-    base_url: &str,
-    model_name: &str,
-) -> Option<usize> {
-    let url = format!("{}/api/show", base_url);
-    let body = serde_json::json!({"name": model_name});
-    let resp = client.post(&url).json(&body).send().await.ok()?;
-    if !resp.status().is_success() {
-        return None;
-    }
-    let text = resp.text().await.ok()?;
-    let value: serde_json::Value = serde_json::from_str(&text).ok()?;
-
-    // The "parameters" field is a newline-delimited string of key-value pairs
-    if let Some(params) = value.get("parameters").and_then(|p| p.as_str()) {
-        for line in params.lines() {
-            let trimmed = line.trim();
-            if trimmed.starts_with("num_ctx") {
-                if let Some(val) = trimmed.split_whitespace().nth(1) {
-                    return val.parse().ok();
-                }
-            }
-        }
-    }
-
-    // Also check model_info for context_length
-    if let Some(info) = value.get("model_info") {
-        // Try common key patterns
-        for key in &[
-            "context_length",
-            "llama.context_length",
-            "general.context_length",
-        ] {
-            if let Some(ctx) = info.get(*key).and_then(|v| v.as_u64()) {
-                return Some(ctx as usize);
-            }
-        }
-    }
-
-    None
-}
-
 /// Print system resource information (RAM and GPU if available).
 fn check_system_resources() {
     println!("System Resources:");

src/commands/git.rs

@@ -72,7 +72,8 @@ async fn suggest_commit_message(config: config::Config) -> Result<()> {
         return Ok(());
     }
 
-    let model_config = config.to_model_config();
+    // Use Fast model for commit message suggestion (lightweight task)
+    let model_config = config.to_model_config_for_role(config::ModelRole::Fast);
 
     let adapter = adapters::llm::create_adapter(&model_config)?;
 
@@ -114,7 +115,8 @@ async fn suggest_pr_title(config: config::Config) -> Result<()> {
         return Ok(());
     }
 
-    let model_config = config.to_model_config();
+    // Use Fast model for PR title suggestion (lightweight task)
+    let model_config = config.to_model_config_for_role(config::ModelRole::Fast);
 
     let adapter = adapters::llm::create_adapter(&model_config)?;
 

src/commands/pr.rs

@@ -81,9 +81,9 @@ pub async fn pr_command(
         let diffs = core::DiffParser::parse_unified_diff(&diff_content)?;
         let git = core::GitIntegration::new(".")?;
 
-        let model_config = config.to_model_config();
-
-        let adapter = adapters::llm::create_adapter(&model_config)?;
+        // Use Fast model for PR summary generation (lightweight task)
+        let fast_config = config.to_model_config_for_role(config::ModelRole::Fast);
+        let adapter = adapters::llm::create_adapter(&fast_config)?;
         let options = core::SummaryOptions {
             include_diagram: config.smart_review_diagram,
         };

src/commands/smart_review.rs

@@ -62,6 +62,20 @@ pub async fn smart_review_command(
     let model_config = config.to_model_config();
 
     let adapter = adapters::llm::create_adapter(&model_config)?;
+
+    // Use Fast model for PR summary and diagram generation (lightweight tasks)
+    let fast_config = config.to_model_config_for_role(config::ModelRole::Fast);
+    let fast_adapter: Box<dyn adapters::llm::LLMAdapter> =
+        if fast_config.model_name != model_config.model_name {
+            info!(
+                "Using fast model '{}' for PR summary/diagram",
+                fast_config.model_name
+            );
+            adapters::llm::create_adapter(&fast_config)?
+        } else {
+            adapters::llm::create_adapter(&model_config)?
+        };
+
     let mut all_comments = Vec::new();
     let mut pr_summary = if config.smart_review_summary {
         match core::GitIntegration::new(&repo_root) {
@@ -72,7 +86,7 @@ pub async fn smart_review_command(
                 match core::PRSummaryGenerator::generate_summary_with_options(
                     &diffs,
                     &git,
-                    adapter.as_ref(),
+                    fast_adapter.as_ref(),
                     options,
                 )
                 .await
@@ -94,7 +108,7 @@ pub async fn smart_review_command(
     };
 
     if config.smart_review_diagram {
-        match core::PRSummaryGenerator::generate_change_diagram(&diffs, adapter.as_ref()).await {
+        match core::PRSummaryGenerator::generate_change_diagram(&diffs, fast_adapter.as_ref()).await {
             Ok(Some(diagram)) => {
                 if let Some(summary) = &mut pr_summary {
                     summary.visual_diff = Some(diagram);

src/config.rs

@@ -20,6 +20,9 @@ pub enum ModelRole {
     Reasoning,
     /// Embedding model for RAG indexing.
     Embedding,
+    /// Fast model for lightweight LLM tasks: PR summaries, commit messages,
+    /// PR titles, diagram generation. Falls back to Weak, then Primary.
+    Fast,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -51,6 +54,11 @@ pub struct Config {
     #[serde(default)]
     pub model_weak: Option<String>,
 
+    /// Fast model for lightweight LLM tasks: PR summaries, commit messages,
+    /// PR titles, diagram generation. Falls back to model_weak, then primary.
+    #[serde(default)]
+    pub model_fast: Option<String>,
+
     /// Reasoning-capable model for complex analysis and self-reflection.
     #[serde(default)]
     pub model_reasoning: Option<String>,
@@ -338,6 +346,7 @@ impl Default for Config {
         Self {
             model: default_model(),
             model_weak: None,
+            model_fast: None,
             model_reasoning: None,
             model_embedding: None,
             fallback_models: Vec::new(),
@@ -914,6 +923,11 @@ impl Config {
             ModelRole::Weak => self.model_weak.as_deref().unwrap_or(&self.model),
             ModelRole::Reasoning => self.model_reasoning.as_deref().unwrap_or(&self.model),
             ModelRole::Embedding => self.model_embedding.as_deref().unwrap_or(&self.model),
+            ModelRole::Fast => self
+                .model_fast
+                .as_deref()
+                .or(self.model_weak.as_deref())
+                .unwrap_or(&self.model),
         }
     }
 
@@ -1650,6 +1664,50 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_model_role_fast_fallback_to_primary() {
+        let config = Config {
+            model: "claude-sonnet-4-6".to_string(),
+            model_fast: None,
+            model_weak: None,
+            ..Config::default()
+        };
+        assert_eq!(config.model_for_role(ModelRole::Fast), "claude-sonnet-4-6");
+    }
+
+    #[test]
+    fn test_model_role_fast_fallback_to_weak() {
+        let config = Config {
+            model: "claude-sonnet-4-6".to_string(),
+            model_fast: None,
+            model_weak: Some("claude-haiku-4-5".to_string()),
+            ..Config::default()
+        };
+        assert_eq!(config.model_for_role(ModelRole::Fast), "claude-haiku-4-5");
+    }
+
+    #[test]
+    fn test_model_role_fast_explicit() {
+        let config = Config {
+            model: "claude-sonnet-4-6".to_string(),
+            model_fast: Some("gpt-4o-mini".to_string()),
+            model_weak: Some("claude-haiku-4-5".to_string()),
+            ..Config::default()
+        };
+        assert_eq!(config.model_for_role(ModelRole::Fast), "gpt-4o-mini");
+    }
+
+    #[test]
+    fn test_to_model_config_for_role_fast() {
+        let config = Config {
+            model: "claude-sonnet-4-6".to_string(),
+            model_fast: Some("gpt-4o-mini".to_string()),
+            ..Config::default()
+        };
+        let fast_config = config.to_model_config_for_role(ModelRole::Fast);
+        assert_eq!(fast_config.model_name, "gpt-4o-mini");
+    }
+
     #[test]
     fn test_to_model_config_for_role_uses_correct_model() {
         let config = Config {

src/core/interactive.rs

@@ -3,14 +3,13 @@ use anyhow::Result;
 use regex::Regex;
 use std::collections::HashSet;
 
-#[allow(dead_code)]
 pub struct InteractiveCommand {
     pub command: CommandType,
     pub args: Vec<String>,
+    #[allow(dead_code)] // Set by webhook handler when PR context is available
     pub context: Option<String>,
 }
 
-#[allow(dead_code)]
 #[derive(Debug, Clone, PartialEq)]
 pub enum CommandType {
     Review,
@@ -21,7 +20,6 @@ pub enum CommandType {
     Config,
 }
 
-#[allow(dead_code)]
 impl InteractiveCommand {
     pub fn parse(comment: &str) -> Option<Self> {
         let command_regex = Regex::new(r"@diffscope\s+(\w+)(?:\s+(.*))?").ok()?;
@@ -186,6 +184,10 @@ impl InteractiveCommand {
         ))
     }
 
+    pub fn help_text() -> String {
+        Self::get_help_text()
+    }
+
     fn get_help_text() -> String {
         r#"## 🤖 DiffScope Interactive Commands
 
@@ -244,6 +246,8 @@ Interactive commands respect these configurations."#
     }
 }
 
+/// Manages per-session ignore patterns from @diffscope ignore commands.
+/// Will be wired into the review pipeline's triage filter.
 #[allow(dead_code)]
 pub struct InteractiveProcessor {
     ignored_patterns: HashSet<String>,