feat: el-ide — native IDE for engram-lang, LSP, type graph, plugin ecosystem

Axum HTTP server (port 7771) serving a single-page IDE with CodeMirror 6
syntax highlighting for engram-lang, a force-directed type graph visualizer,
LSP (completions, hover, diagnostics), SSE-streamed build/run output, a
plugin host with five first-party plugins, and a reasoning panel that proxies
to engram-server. 28 tests across three crates, zero warnings.

crates/el-ide-server/src/api/build.rs

@@ -0,0 +1,158 @@
+//! Build and run API — streams output via SSE.
+
+use std::convert::Infallible;
+
+use axum::{
+    extract::State,
+    Json,
+    response::{
+        sse::{Event, KeepAlive, Sse},
+        IntoResponse,
+    },
+};
+use serde::Deserialize;
+use tokio::io::AsyncBufReadExt;
+
+use crate::{sse::classify_line, AppState};
+
+// ── Request types ─────────────────────────────────────────────────────────────
+
+#[derive(Debug, Deserialize)]
+pub struct BuildRequest {
+    /// Target: "debug" | "release" | "prod"
+    #[serde(default = "default_target")]
+    pub target: String,
+    /// Optional specific file to build; otherwise builds whole project.
+    pub file: Option<String>,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct RunRequest {
+    pub file: String,
+}
+
+fn default_target() -> String {
+    "debug".into()
+}
+
+// ── Handlers ──────────────────────────────────────────────────────────────────
+
+/// POST /api/build — streams build output as SSE.
+pub async fn build_handler(
+    State(state): State<AppState>,
+    Json(req): Json<BuildRequest>,
+) -> impl IntoResponse {
+    let project_path = state.config.project_path.clone();
+    let stream = build_stream(project_path, req);
+    Sse::new(stream).keep_alive(KeepAlive::default())
+}
+
+/// POST /api/run — compiles and runs a file, streams output as SSE.
+pub async fn run_handler(
+    State(state): State<AppState>,
+    Json(req): Json<RunRequest>,
+) -> impl IntoResponse {
+    let project_path = state.config.project_path.clone();
+    let stream = run_stream(project_path, req);
+    Sse::new(stream).keep_alive(KeepAlive::default())
+}
+
+// ── Stream builders ───────────────────────────────────────────────────────────
+
+fn build_stream(
+    project_path: String,
+    req: BuildRequest,
+) -> impl tokio_stream::Stream<Item = Result<Event, Infallible>> {
+    async_stream::stream! {
+        let el_bin = el_binary();
+        let mut cmd = tokio::process::Command::new(&el_bin);
+
+        if let Some(ref file) = req.file {
+            let file_path = format!("{project_path}/{file}");
+            cmd.arg("build").arg(&file_path).arg("--target").arg(&req.target);
+        } else {
+            let main = format!("{project_path}/src/main.el");
+            cmd.arg("build").arg(&main).arg("--target").arg(&req.target);
+        }
+
+        cmd.stdout(std::process::Stdio::piped())
+           .stderr(std::process::Stdio::piped())
+           .current_dir(&project_path);
+
+        yield Ok(Event::default().event("info").data(format!("Running: el build --target {}", req.target)));
+
+        match cmd.spawn() {
+            Err(e) => {
+                yield Ok(Event::default().event("error").data(format!("Failed to start el: {e}")));
+                yield Ok(Event::default().event("done").data("1"));
+            }
+            Ok(mut child) => {
+                if let Some(stdout) = child.stdout.take() {
+                    let mut reader = tokio::io::BufReader::new(stdout).lines();
+                    while let Ok(Some(line)) = reader.next_line().await {
+                        yield Ok(classify_line(&line));
+                    }
+                }
+                if let Some(stderr) = child.stderr.take() {
+                    let mut reader = tokio::io::BufReader::new(stderr).lines();
+                    while let Ok(Some(line)) = reader.next_line().await {
+                        yield Ok(classify_line(&line));
+                    }
+                }
+                let code = child.wait().await.map(|s| s.code().unwrap_or(0)).unwrap_or(1);
+                yield Ok(Event::default().event("done").data(code.to_string()));
+            }
+        }
+    }
+}
+
+fn run_stream(
+    project_path: String,
+    req: RunRequest,
+) -> impl tokio_stream::Stream<Item = Result<Event, Infallible>> {
+    async_stream::stream! {
+        let el_bin = el_binary();
+        let file_path = format!("{project_path}/{}", req.file);
+
+        yield Ok(Event::default().event("info").data(format!("Running: el run {}", req.file)));
+
+        let mut cmd = tokio::process::Command::new(&el_bin);
+        cmd.arg("run")
+           .arg(&file_path)
+           .stdout(std::process::Stdio::piped())
+           .stderr(std::process::Stdio::piped())
+           .current_dir(&project_path);
+
+        match cmd.spawn() {
+            Err(e) => {
+                yield Ok(Event::default().event("error").data(format!("Failed to start el: {e}")));
+                yield Ok(Event::default().event("done").data("1"));
+            }
+            Ok(mut child) => {
+                if let Some(stdout) = child.stdout.take() {
+                    let mut reader = tokio::io::BufReader::new(stdout).lines();
+                    while let Ok(Some(line)) = reader.next_line().await {
+                        yield Ok(Event::default().event("output").data(line));
+                    }
+                }
+                if let Some(stderr) = child.stderr.take() {
+                    let mut reader = tokio::io::BufReader::new(stderr).lines();
+                    while let Ok(Some(line)) = reader.next_line().await {
+                        yield Ok(classify_line(&line));
+                    }
+                }
+                let code = child.wait().await.map(|s| s.code().unwrap_or(0)).unwrap_or(1);
+                yield Ok(Event::default().event("done").data(code.to_string()));
+            }
+        }
+    }
+}
+
+// ── Helpers ───────────────────────────────────────────────────────────────────
+
+fn el_binary() -> String {
+    if let Ok(path) = which::which("el") {
+        return path.to_string_lossy().to_string();
+    }
+    "el".to_string()
+}