Add capture() to spawn, add rsync itemize parser

lib/itemize.js

@@ -0,0 +1,56 @@
+/**
+ * Parse rsync --itemize-changes output into a structured change list.
+ *
+ * rsync itemize format: 11-character code + space + path
+ *
+ * Code structure: YXcstpoguax
+ *   Y = update type: > (transfer), * (message/delete), c (local change), . (no update), h (hard link)
+ *   X = file type:   f (file), d (dir), L (symlink), D (device), S (special)
+ *   remaining chars = what changed (size, time, perms, etc.) or '+++++++++' for new
+ *
+ * We care about:
+ *   >f... = file transferred (new or modified)
+ *   *deleting = file deleted
+ *   cd... = directory (ignored for delta purposes)
+ */
+
+/**
+ * @typedef {{ status: 'added'|'modified'|'deleted', path: string }} Change
+ */
+
+/**
+ * Parse rsync --itemize-changes stdout into a list of file changes.
+ * @param {string} output
+ * @returns {Change[]}
+ */
+export function parseItemize(output) {
+  const changes = [];
+
+  for (const raw of output.split('\n')) {
+    const line = raw.trimEnd();
+    if (!line) continue;
+
+    // Deleted files: "*deleting   path/to/file"
+    if (line.startsWith('*deleting ')) {
+      const path = line.slice('*deleting '.length).trimStart();
+      // Skip directory deletions (trailing slash)
+      if (!path.endsWith('/')) {
+        changes.push({ status: 'deleted', path });
+      }
+      continue;
+    }
+
+    // File transfers: ">f......... path" (new or modified)
+    if (line.length > 12 && line[0] === '>' && line[1] === 'f') {
+      const code = line.slice(0, 11);
+      const path = line.slice(12);
+      const isNew = code.slice(2) === '+++++++++';
+      changes.push({ status: isNew ? 'added' : 'modified', path });
+      continue;
+    }
+
+    // Everything else (dirs, symlinks, attribute-only changes) — ignore
+  }
+
+  return changes;
+}

lib/spawn.js

@@ -4,17 +4,14 @@
 import { spawn } from 'child_process';
 
 /**
- * Spawn a process and stream its output.
+ * Spawn a process and stream its output to stdout/stderr.
  * @param {string} cmd
  * @param {string[]} args
- * @param {{ dryRun?: boolean, label?: string }} opts
+ * @param {{ dryRun?: boolean }} opts
  * @returns {Promise<void>}
  */
-export async function run(cmd, args, { dryRun = false, label } = {}) {
-  const display = [cmd, ...args].join(' ');
-  if (label) console.log(`[${label}] ${display}`);
-  else console.log(`$ ${display}`);
-
+export async function run(cmd, args, { dryRun = false } = {}) {
+  console.log(`$ ${[cmd, ...args].join(' ')}`);
   if (dryRun) return;
 
   return new Promise((resolve, reject) => {
@@ -26,3 +23,25 @@ export async function run(cmd, args, { dryRun = false, label } = {}) {
     });
   });
 }
+
+/**
+ * Spawn a process and capture stdout as a string.
+ * stderr is inherited (shown to user). Never used in dry-run context.
+ * @param {string} cmd
+ * @param {string[]} args
+ * @returns {Promise<string>}
+ */
+export async function capture(cmd, args) {
+  console.log(`$ ${[cmd, ...args].join(' ')}`);
+
+  return new Promise((resolve, reject) => {
+    const child = spawn(cmd, args, { stdio: ['inherit', 'pipe', 'inherit'] });
+    const chunks = [];
+    child.stdout.on('data', chunk => chunks.push(chunk));
+    child.on('error', reject);
+    child.on('close', code => {
+      if (code === 0) resolve(Buffer.concat(chunks).toString('utf8'));
+      else reject(new Error(`${cmd} exited with code ${code}`));
+    });
+  });
+}