refactor(handlers): extract LearnParams + reusable RBAC helpers

learn_handler refactored:
- Extract LearnParams struct with validation + bounds clamping
- Extract store_compacted_memory helper
- Extract build_learn_response helper
- Reuse check_project_write_access for RBAC

ingest_handler refactored:
- Extract check_project_write_access (reusable)
- Extract execute_ingest helper

New tests (6 total):
- LearnParams validation tests

Total tests: 694 (was 688)

crates/mem-cli/src/handlers/learn.rs

@@ -0,0 +1,172 @@
+/// Learn Handler Helpers
+/// 
+/// Extracted to reduce learn_handler complexity.
+
+use actix_web::HttpResponse;
+use serde_json::{json, Value};
+
+// ============================================================================
+// Learn Parameters
+// ============================================================================
+
+/// Validated learn request parameters
+#[derive(Debug, Clone)]
+pub struct LearnParams {
+    pub project: String,
+    pub text: String,
+    pub question: String,
+    pub memory_budget: u32,
+    pub chunk_size: usize,
+    pub model: String,
+}
+
+impl LearnParams {
+    /// Parse and validate learn request body
+    pub fn from_body(body: &Value) -> Result<Self, LearnParamsError> {
+        let project = body["project"]
+            .as_str()
+            .unwrap_or("knowledge")
+            .to_string();
+        
+        let text = body["text"]
+            .as_str()
+            .filter(|t| !t.trim().is_empty())
+            .ok_or(LearnParamsError::MissingText)?
+            .to_string();
+        
+        let question = body["query"]
+            .as_str()
+            .unwrap_or("What are the key facts, patterns, and practices in this knowledge?")
+            .to_string();
+        
+        let memory_budget = body["memory_budget"]
+            .as_u64()
+            .unwrap_or(4096)
+            .clamp(256, 32768) as u32;
+        
+        let chunk_size = body["chunk_size"]
+            .as_u64()
+            .unwrap_or(2000)
+            .clamp(500, 10000) as usize;
+        
+        let model = body["model"]
+            .as_str()
+            .unwrap_or("qwen2.5:3b-instruct")
+            .to_string();
+        
+        Ok(Self { project, text, question, memory_budget, chunk_size, model })
+    }
+}
+
+/// Learn parameter validation errors
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum LearnParamsError {
+    MissingText,
+}
+
+impl LearnParamsError {
+    pub fn to_response(&self) -> HttpResponse {
+        let reason = match self {
+            Self::MissingText => "missing required field: text",
+        };
+        HttpResponse::BadRequest().json(json!({
+            "error": "bad_request",
+            "reason": reason
+        }))
+    }
+}
+
+// ============================================================================
+// Learn Response Builder
+// ============================================================================
+
+/// Build learn response JSON
+pub fn build_learn_response(
+    project: &str,
+    model: &str,
+    chunks_seen: u32,
+    chunks_used: u32,
+    memory: &str,
+    stored: bool,
+) -> HttpResponse {
+    HttpResponse::Ok().json(json!({
+        "project": project,
+        "status": "completed",
+        "chunks_seen": chunks_seen,
+        "chunks_used": chunks_used,
+        "memory": memory,
+        "memory_tokens": memory.len() / 4,
+        "stored": stored,
+        "model": model,
+    }))
+}
+
+// ============================================================================
+// Tests
+// ============================================================================
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_learn_params_valid() {
+        let body = json!({
+            "project": "homelab",
+            "text": "Some knowledge to learn"
+        });
+        let params = LearnParams::from_body(&body).unwrap();
+        
+        assert_eq!(params.project, "homelab");
+        assert_eq!(params.text, "Some knowledge to learn");
+        assert_eq!(params.memory_budget, 4096);
+        assert_eq!(params.chunk_size, 2000);
+    }
+
+    #[test]
+    fn test_learn_params_defaults() {
+        let body = json!({"text": "content"});
+        let params = LearnParams::from_body(&body).unwrap();
+        
+        assert_eq!(params.project, "knowledge");
+        assert_eq!(params.model, "qwen2.5:3b-instruct");
+    }
+
+    #[test]
+    fn test_learn_params_custom_values() {
+        let body = json!({
+            "text": "content",
+            "memory_budget": 8192,
+            "chunk_size": 3000,
+            "model": "gpt-4"
+        });
+        let params = LearnParams::from_body(&body).unwrap();
+        
+        assert_eq!(params.memory_budget, 8192);
+        assert_eq!(params.chunk_size, 3000);
+        assert_eq!(params.model, "gpt-4");
+    }
+
+    #[test]
+    fn test_learn_params_clamped_budget() {
+        let body = json!({"text": "x", "memory_budget": 999999});
+        let params = LearnParams::from_body(&body).unwrap();
+        assert_eq!(params.memory_budget, 32768);
+
+        let body = json!({"text": "x", "memory_budget": 10});
+        let params = LearnParams::from_body(&body).unwrap();
+        assert_eq!(params.memory_budget, 256);
+    }
+
+    #[test]
+    fn test_learn_params_missing_text() {
+        let body = json!({"project": "test"});
+        assert_eq!(LearnParams::from_body(&body).unwrap_err(), LearnParamsError::MissingText);
+    }
+
+    #[test]
+    fn test_learn_params_empty_text() {
+        let body = json!({"text": "   "});
+        assert_eq!(LearnParams::from_body(&body).unwrap_err(), LearnParamsError::MissingText);
+    }
+}

crates/mem-cli/src/handlers/mod.rs

@@ -5,6 +5,8 @@
 
 pub mod query;
 pub mod ingest;
+pub mod learn;
 
 pub use query::*;
 pub use ingest::*;
+pub use learn::*;