fix(storage): report real SMB share free space, not local overlay

Mount-health card showed ~31GB free for the growing SMB share when the NAS
actually has multi-TB. mam-api never mounts the CIFS share, so df on the
container's /growing path reported the local overlay filesystem. Now query
the share's true capacity via 'smbclient -c du' (no mount needed) using the
configured credentials; falls back to the local df + surfaces the probe
error if the share is unreachable. Added smbclient to the mam-api image.

services/mam-api/Dockerfile

@@ -1,7 +1,10 @@
 FROM node:22-slim
-# unzip/tar needed for SDK upload extraction (see routes/sdk.js)
+# unzip/tar  → SDK upload extraction (see routes/sdk.js)
+# smbclient   → query the growing-files SMB share's real free space for the
+#               storage/Mount-health card (mam-api never mounts the share, so
+#               `df` would report the local overlay, not the NAS quota).
 RUN apt-get update \
- && apt-get install -y --no-install-recommends unzip tar ca-certificates \
+ && apt-get install -y --no-install-recommends unzip tar ca-certificates smbclient \
  && rm -rf /var/lib/apt/lists/*
 WORKDIR /app
 COPY package*.json ./

services/mam-api/src/routes/storage.js

@@ -5,12 +5,13 @@
 import express from 'express';
 import fs from 'node:fs';
 import { promisify } from 'node:util';
-import { exec as execCb } from 'node:child_process';
+import { exec as execCb, execFile as execFileCb } from 'node:child_process';
 import { HeadBucketCommand, ListObjectsV2Command } from '@aws-sdk/client-s3';
 import pool from '../db/pool.js';
 import { s3Client, getS3Bucket } from '../s3/client.js';
 
 const exec = promisify(execCb);
+const execFile = promisify(execFileCb);
 const router = express.Router();
 
 // Defaults mirrored from settings.js so the overview never returns nulls.
@@ -103,6 +104,42 @@ async function probeS3Bucket() {
   return out;
 }
 
+// Query the growing-files SMB share's real capacity WITHOUT mounting it.
+// mam-api never mounts the CIFS share, so df on the container path reports the
+// local overlay (tens of GB), not the multi-TB NAS volume. `smbclient -c du`
+// returns "<N> blocks of size 1024. <M> blocks available" for the share, which
+// is the actual free/total the operator cares about.
+async function probeSmbShare({ mount, username, password, vers }) {
+  const out = { reachable: false, free_bytes: null, total_bytes: null, error: null };
+  if (!mount) { out.error = 'no smb mount configured'; return out; }
+  // Normalize smb://host/share or \\host\share → //host/share for smbclient.
+  let unc = String(mount).trim().replace(/\\/g, '/').replace(/^smb:\/\//i, '//');
+  if (!unc.startsWith('//')) unc = '//' + unc.replace(/^\/+/, '');
+  const user = `${username || ''}%${password || ''}`;
+  const args = [
+    unc, '-U', user,
+    ...(vers ? ['-m', `SMB${String(vers).replace(/\./g, '_').replace(/_0$/, '')}`] : []),
+    '-c', 'du',
+  ];
+  try {
+    // execFile avoids shell-quoting the password. 6s cap so a dead NAS can't hang.
+    const { stdout } = await execFile('smbclient', args, { timeout: 6000 });
+    // "  1890828485120 blocks of size 1024. 1890776477696 blocks available"
+    const m = stdout.match(/(\d+)\s+blocks of size\s+(\d+)\.\s+(\d+)\s+blocks available/i);
+    if (m) {
+      const blockSize = parseInt(m[2], 10) || 1024;
+      out.total_bytes = parseInt(m[1], 10) * blockSize;
+      out.free_bytes  = parseInt(m[3], 10) * blockSize;
+      out.reachable   = true;
+    } else {
+      out.error = 'could not parse smbclient du output';
+    }
+  } catch (err) {
+    out.error = (err.stderr ? String(err.stderr).trim() : err.message).slice(0, 200);
+  }
+  return out;
+}
+
 // GET /api/v1/storage/overview
 // Consolidated read-only view of the storage subsystem for the admin UI.
 router.get('/overview', async (req, res, next) => {
@@ -115,6 +152,29 @@ router.get('/overview', async (req, res, next) => {
     const containerPath = growingRaw.growing_path || '/growing';
     const mount = await probeGrowingPath(containerPath);
 
+    // Real capacity comes from the SMB share itself, NOT the local container
+    // path (mam-api never mounts the share, so df reports the tiny overlay).
+    // Query the NAS quota directly via smbclient when a mount is configured.
+    let smbFree = null, smbTotal = null, smbReachable = false, capacityError = mount.error;
+    if (growingEnabled) {
+      const creds = await readSettings(['growing_smb_username', 'growing_smb_password', 'growing_smb_vers']);
+      const smb = await probeSmbShare({
+        mount: growingRaw.growing_smb_mount,
+        username: creds.growing_smb_username,
+        password: creds.growing_smb_password,
+        vers: creds.growing_smb_vers,
+      });
+      if (smb.reachable) {
+        smbFree = smb.free_bytes; smbTotal = smb.total_bytes; smbReachable = true; capacityError = null;
+      } else {
+        // Fall back to the local-path df numbers, but surface why the share
+        // probe failed so the card can show it.
+        smbFree = mount.free_bytes; smbTotal = mount.total_bytes; capacityError = smb.error || mount.error;
+      }
+    } else {
+      smbFree = mount.free_bytes; smbTotal = mount.total_bytes;
+    }
+
     // S3 — bucket name comes from the live client (env or DB-loaded), not
     // a fresh DB read, so we report exactly what the running client uses.
     const s3 = await probeS3Bucket();
@@ -132,9 +192,12 @@ router.get('/overview', async (req, res, next) => {
         promote_after_seconds: parseInt(growingRaw.growing_promote_after_seconds, 10) || 8,
         exists: mount.exists,
         writable: mount.writable,
-        free_bytes: mount.free_bytes,
-        total_bytes: mount.total_bytes,
-        error: mount.error,
+        // free/total now reflect the actual SMB share (smbclient du) when a
+        // mount is configured; smb_reachable says whether that probe succeeded.
+        free_bytes: smbFree,
+        total_bytes: smbTotal,
+        smb_reachable: smbReachable,
+        error: capacityError,
       },
       s3: {
         endpoint: s3SettingsRaw.s3_endpoint || process.env.S3_ENDPOINT || '',