feat(lanes): detect docker-compose database/Redis and wire ENV_REWRITE (A3)

server/lib/lane-detect.js

@@ -11,6 +11,7 @@
 
 const fs = require("node:fs");
 const path = require("node:path");
+const yaml = require("js-yaml");
 
 /**
  * A name safe to embed as literal text inside a generated shell script (an
@@ -46,6 +47,97 @@ function pickScript(pkg, candidates) {
   return null;
 }
 
+/**
+ * A repo-name-derived DB_PREFIX: lowercase alnum + underscore, "_l" suffix
+ * (lane N's actual name becomes "<prefix>N"), matching the convention in
+ * the postgres-compose profile template's example.
+ *
+ * @param {string} repoPath - Absolute path to the repository root.
+ * @returns {string}
+ */
+function dbPrefixFor(repoPath) {
+  const base = path
+    .basename(repoPath)
+    .toLowerCase()
+    .replace(/[^a-z0-9]+/g, "_")
+    .replace(/^_+|_+$/g, "");
+  return `${base || "app"}_l`;
+}
+
+/**
+ * The first docker-compose service name matching `pattern`, or null. Reads
+ * `docker-compose.yml`/`.yaml` at the repo root; never executes it.
+ *
+ * @param {string} repoPath - Absolute path to the repository root.
+ * @param {RegExp} pattern - Pattern to match service name.
+ * @returns {string|null}
+ */
+function findComposeService(repoPath, pattern) {
+  for (const name of ["docker-compose.yml", "docker-compose.yaml"]) {
+    let doc;
+    try {
+      doc = yaml.load(fs.readFileSync(path.join(repoPath, name), "utf8"));
+    } catch {
+      continue;
+    }
+    const services = doc && typeof doc.services === "object" ? doc.services : {};
+    for (const serviceName of Object.keys(services)) {
+      if (pattern.test(serviceName) && IDENTIFIER_RE.test(serviceName)) return serviceName;
+    }
+  }
+  return null;
+}
+
+/**
+ * Where a lane's .env lives for this layout: backend/.env in a monorepo,
+ * .env at the root for single-service. Returns the source to seed FROM
+ * (real .env, else .env.example) or null when neither exists.
+ *
+ * @param {string} repoPath - Absolute path to the repository root.
+ * @param {string} envDir - Directory where .env lives (e.g. "backend" or ".").
+ * @returns {object|null}
+ */
+function findEnvSource(repoPath, envDir) {
+  const dir = path.join(repoPath, envDir);
+  const real = path.join(dir, ".env");
+  const example = path.join(dir, ".env.example");
+  const relFile = path.join(envDir, ".env").replace(/\\/g, "/").replace(/^\.\//, "");
+  if (fs.existsSync(real)) return { file: relFile, source: relFile, fromExample: false };
+  if (fs.existsSync(example)) {
+    return { file: relFile, source: `${relFile}.example`, fromExample: true };
+  }
+  return null;
+}
+
+/**
+ * Detect database and Redis services from docker-compose.yml and wire up
+ * .env rewriting if services are found.
+ *
+ * @param {string} repoPath - Absolute path to the repository root.
+ * @param {string} envDir - Directory where .env lives (e.g. "backend" or ".").
+ * @returns {object}
+ */
+function detectDatabaseAndEnv(repoPath, envDir) {
+  const dbService = findComposeService(repoPath, /postgres/i);
+  const redis = findComposeService(repoPath, /redis/i) !== null;
+  const database = dbService
+    ? { dbPrefix: dbPrefixFor(repoPath), dbService, dbKind: "postgres" }
+    : null;
+
+  let env = null;
+  if (database || redis) {
+    const found = findEnvSource(repoPath, envDir);
+    if (found) {
+      const rewrite = [];
+      if (database) rewrite.push("DATABASE_URL");
+      if (redis) rewrite.push("REDIS_URL");
+      env = { dir: envDir, ...found, rewrite };
+    }
+  }
+
+  return { database, redis, env };
+}
+
 /**
  * Detect a Node.js project's layout and, for each service, which npm script
  * to run. Returns null when neither supported layout matches — the caller
@@ -59,28 +151,40 @@ function detectNode(repoPath) {
   const frontendPkg = readPackageJson(path.join(repoPath, "frontend"));
 
   if (backendPkg && frontendPkg) {
+    const { database, redis, env } = detectDatabaseAndEnv(repoPath, "backend");
     return {
       layout: "monorepo",
       services: {
         backend: { dir: "backend", script: pickScript(backendPkg, ["start", "dev"]) },
         frontend: { dir: "frontend", script: pickScript(frontendPkg, ["preview", "dev"]) },
       },
-      database: null,
-      env: null,
+      database,
+      redis,
+      env,
     };
   }
 
   const rootPkg = readPackageJson(repoPath);
   if (rootPkg) {
+    const { database, redis, env } = detectDatabaseAndEnv(repoPath, ".");
     return {
       layout: "single-service",
       services: { app: { dir: ".", script: pickScript(rootPkg, ["start", "dev"]) } },
-      database: null,
-      env: null,
+      database,
+      redis,
+      env,
     };
   }
 
   return null;
 }
 
-module.exports = { IDENTIFIER_RE, readPackageJson, pickScript, detectNode };
+module.exports = {
+  IDENTIFIER_RE,
+  readPackageJson,
+  pickScript,
+  dbPrefixFor,
+  findComposeService,
+  findEnvSource,
+  detectNode,
+};