feat: implement resource resizing for VMs with storage management

- Added KnownHostsManager to handle cleanup of SSH known_hosts entries upon VM deletion.
- Introduced disk_size_bytes method in ImageStore to read logical disk capacity.
- Enhanced LifecycleService to manage VM resource resizing, including CPU, RAM, and storage.
- Updated application configuration to support known_hosts_files for SSH management.
- Modified dashboard to include resource resizing options in the UI.
- Improved error handling and validation for resource inputs in the dashboard.
- Removed obsolete .pyc files from the repository.

uvm/app.py

@@ -9,6 +9,7 @@ from .config import Settings
 from .firecracker.process import FirecrackerProcessManager
 from .images import ImageStore
 from .install import Installer
+from .known_hosts import KnownHostsManager
 from .lifecycle import LifecycleService
 from .network import NetworkManager
 from .state import StateStore
@@ -32,7 +33,8 @@ def build_application(emit: Callable[[str], None] | None = print) -> Application
     images = ImageStore(settings, runner)
     network = NetworkManager(settings, runner)
     process = FirecrackerProcessManager(settings)
-    lifecycle = LifecycleService(settings, state_store, images, network, process)
+    known_hosts = KnownHostsManager(settings)
+    lifecycle = LifecycleService(settings, state_store, images, network, process, known_hosts=known_hosts)
     installer = Installer(settings, runner, state_store, emit=emit)
     return Application(
         settings=settings,

uvm/config.py

@@ -40,6 +40,7 @@ class Settings:
     api_token: str | None = None
     api_tls_cert: Path | None = None
     api_tls_key: Path | None = None
+    known_hosts_files: tuple[Path, ...] | None = None
     api_timeout_s: float = 2.0
     api_socket_timeout_s: float = 5.0
     terminate_timeout_s: float = 5.0
@@ -66,6 +67,8 @@ class Settings:
             raise ConfigurationError("gateway must be a usable host address")
         if len(self.bridge) > 15:
             raise ConfigurationError("bridge name must be 15 characters or fewer")
+        if self.known_hosts_files is not None and any(not path.is_absolute() for path in self.known_hosts_files):
+            raise ConfigurationError("UVM_KNOWN_HOSTS_FILES must contain absolute file paths")
         if self.api_token is not None:
             if not self.api_token or not all(33 <= ord(character) <= 126 for character in self.api_token):
                 raise ConfigurationError(
@@ -148,6 +151,7 @@ class Settings:
             api_token=_optional_environment_value("UVM_API_TOKEN"),
             api_tls_cert=_optional_environment_path("UVM_API_TLS_CERT"),
             api_tls_key=_optional_environment_path("UVM_API_TLS_KEY"),
+            known_hosts_files=_known_hosts_environment_paths(),
         )
 
 
@@ -161,6 +165,16 @@ def _optional_environment_path(name: str) -> Path | None:
     return Path(value).expanduser() if value else None
 
 
+def _known_hosts_environment_paths() -> tuple[Path, ...] | None:
+    value = _optional_environment_value("UVM_KNOWN_HOSTS_FILES")
+    if value is None:
+        return None
+    parts = value.split(os.pathsep)
+    if any(not part for part in parts):
+        raise ConfigurationError("UVM_KNOWN_HOSTS_FILES must be a colon-separated list of file paths")
+    return tuple(Path(part).expanduser() for part in parts)
+
+
 def _boolean_environment_value(name: str, *, default: bool) -> bool:
     value = os.environ.get(name)
     if value is None:

uvm/dashboard/static/css/dashboard.css

@@ -469,7 +469,8 @@ input[type='checkbox'] { width: 14px; height: 14px; accent-color: #9f9259; curso
 .ssh-command { display: flex; align-items: center; justify-content: space-between; gap: 10px; padding: 5px 8px 5px 14px; border: 1px solid #fff9; border-radius: 12px; background: #fdfbfc9c; }
 .ssh-command code { font-family: var(--mono); font-size: 10px; color: #918060; overflow-wrap: anywhere; }
 .ssh-command .icon-button { width: 27px; height: 27px; }
-.ports-panel, .log-panel { margin-top: 15px; }
+.ports-panel, .log-panel, .resources-panel { margin-top: 15px; }
+.storage-field { margin-top: 18px; }
 .port-editor { padding-top: 5px; }
 .log-output { max-height: 320px; min-height: 145px; margin: 0; padding: 17px; border: 1px solid #ffffff7a; border-radius: 13px; background: #e9e2ed8c; color: var(--ink-soft); font-family: var(--mono); font-size: 11px; line-height: 1.9; overflow: auto; white-space: pre-wrap; overflow-wrap: anywhere; }
 .detail-delete-row { display: flex; align-items: center; justify-content: space-between; gap: 15px; margin-top: 20px; padding: 0 4px; color: #ad94b6; font-size: 9px; }
@@ -878,8 +879,8 @@ input[type='checkbox'] { width: 14px; height: 14px; accent-color: #9f9259; curso
   .field input { font-size: 12px; }
   .detail-delete-row { align-items: flex-start; }
   .detail-delete-row > span { max-width: 170px; }
-  .ports-panel > .section-heading, .log-panel > .section-heading { align-items: flex-start; }
-  .ports-panel > .section-heading > div:first-child, .log-panel > .section-heading > div:first-child { flex: 1; }
+  .ports-panel > .section-heading, .log-panel > .section-heading, .resources-panel > .section-heading { align-items: flex-start; }
+  .ports-panel > .section-heading > div:first-child, .log-panel > .section-heading > div:first-child, .resources-panel > .section-heading > div:first-child { flex: 1; }
   .auth-screen { padding: 20px; }
   .auth-window { grid-template-columns: 1fr; min-height: 0; max-width: 440px; }
   .auth-story { min-height: 240px; padding: 26px; border-right: 0; }

uvm/dashboard/static/index.html

@@ -171,6 +171,16 @@
             <div class="page-heading detail-heading"><div><span class="subtle-label">A closer look</span><h1 id="detail-heading" tabindex="-1"></h1><span id="detail-id" class="mono muted"></span></div><div id="detail-actions" class="button-row"></div></div>
             <div id="detail-error" class="notice notice-error" hidden></div>
             <div class="detail-grid"><article class="soft-panel detail-card"><header class="section-heading"><h2>The essentials</h2><span id="detail-status"></span></header><dl id="detail-config" class="detail-list"></dl></article><article class="soft-panel detail-card"><header class="section-heading"><h2>A place in the network</h2><svg class="icon caption-icon"><use href="#i-network"/></svg></header><dl id="detail-network" class="detail-list"></dl></article></div>
+            <article class="soft-panel resources-panel">
+              <header class="section-heading"><div><h2>Room to grow</h2><span>Adjust CPU, memory, and private storage.</span></div><button id="edit-resources-btn" class="button button-small" type="button" data-action="edit-resources">Resize resources</button></header>
+              <p id="resize-note" class="panel-footnote">Resource changes stop the machine, apply the new size, and start it again with its existing IP and guest credentials.</p>
+              <form id="resize-form" hidden>
+                <div class="form-grid"><label class="field" for="resize-cpu"><span>CPU capacity</span><input id="resize-cpu" type="number" min="0.01" step="any" placeholder="Keep current CPU" /></label><label class="field" for="resize-ram"><span>Memory</span><input id="resize-ram" type="text" placeholder="Keep current memory" /><small>At least 128 MiB. For example, 4G.</small></label></div>
+                <label class="field storage-field" for="resize-storage"><span>Private storage</span><input id="resize-storage" type="text" placeholder="Keep current size (at least 30G)" /><small>Minimum 30 GiB. A smaller disk must still fit the existing filesystem data.</small></label>
+                <p id="resize-error" class="form-error" role="alert"></p>
+                <div class="button-row"><button id="resize-submit" class="button button-primary button-small" type="submit">Resize &amp; restart</button><button class="button button-quiet button-small" type="button" data-action="cancel-resize">Cancel</button></div>
+              </form>
+            </article>
             <article class="soft-panel ssh-panel"><div><span class="round-icon"><svg class="icon"><use href="#i-terminal"/></svg></span><div><h2>A direct connection</h2><p id="ssh-hint" class="muted"></p></div></div><div class="ssh-command"><code id="ssh-command"></code><button class="icon-button" data-action="copy-ssh" type="button" aria-label="Copy SSH command"><svg class="icon"><use href="#i-copy"/></svg></button></div></article>
             <article class="soft-panel ports-panel"><header class="section-heading"><div><h2>Private port policy</h2><span>Just the connections this machine needs.</span></div><div class="button-row"><button id="edit-ports-btn" class="button button-small" type="button" data-action="edit-ports">Edit rules</button><button id="sync-ports-btn" class="icon-button" type="button" data-action="sync-ports" aria-label="Sync port policy" title="Sync port policy"><svg class="icon"><use href="#i-refresh"/></svg></button></div></header><div id="detail-ports" class="port-list"></div><form id="port-editor" class="port-editor" hidden><label class="field" for="port-input"><span>Port rules <small>PORT:TCP, PORT:HTTP, or PORT:HTTPS</small></span><input id="port-input" type="text" placeholder="22:TCP, 80:HTTP, 443:HTTPS" spellcheck="false" /></label><p id="port-error" class="form-error" role="alert"></p><div class="button-row"><button class="button button-primary button-small" type="submit" value="set">Replace rules</button><button id="open-ports-btn" class="button button-small" type="submit" value="open">Open ports</button><button id="close-ports-btn" class="button button-small" type="submit" value="close">Close ports</button><button class="button button-quiet button-small" type="button" data-action="cancel-ports">Cancel</button></div><p class="panel-footnote">An empty replacement creates a managed policy with no inbound TCP ports.</p></form></article>
             <article class="soft-panel log-panel"><header class="section-heading"><div><h2>A window into the runtime</h2><span>Recent Firecracker log entries.</span></div><div class="button-row"><label class="select-wrap"><span class="sr-only">Log tail length</span><select id="log-tail"><option value="100">100 lines</option><option value="250">250 lines</option><option value="500">500 lines</option><option value="1000">1,000 lines</option></select></label><button id="log-refresh-btn" class="icon-button" type="button" data-action="refresh-logs" aria-label="Refresh logs"><svg class="icon"><use href="#i-refresh"/></svg></button></div></header><pre id="log-output" class="log-output" tabindex="0"></pre><p id="log-meta" class="panel-footnote"></p></article>
@@ -182,6 +192,7 @@
           <div class="page-heading"><div><span class="subtle-label">Every idea starts somewhere</span><h1 id="create-heading" tabindex="-1">Make something new<span class="heading-period">.</span></h1></div><a class="quiet-link" href="#vms">Back to machines <svg class="icon"><use href="#i-arrow"/></svg></a></div>
           <form id="create-form" class="create-layout">
             <div class="create-fields"><section class="soft-panel form-section"><header class="section-heading"><div><h2><span class="step-number">01</span>A name and a little space</h2><span>Give your new machine a shape.</span></div></header><label class="field" for="create-name"><span>Machine name <small>Optional</small></span><input id="create-name" type="text" name="name" placeholder="e.g. my-little-server" pattern="[a-z][a-z0-9\-]{0,62}" maxlength="63" autocomplete="off" /></label><fieldset class="preset-fieldset"><legend>Start with a size</legend><div class="size-presets"><button class="size-preset active" type="button" data-preset="small" aria-pressed="true"><svg class="icon"><use href="#i-server"/></svg><strong>Small</strong><span>1 vCPU · 512 MiB</span></button><button class="size-preset" type="button" data-preset="balanced" aria-pressed="false"><svg class="icon"><use href="#i-server"/></svg><strong>Balanced</strong><span>2 vCPU · 1 GiB</span></button><button class="size-preset" type="button" data-preset="roomy" aria-pressed="false"><svg class="icon"><use href="#i-server"/></svg><strong>Roomy</strong><span>4 vCPU · 2 GiB</span></button></div></fieldset><div class="form-grid"><label class="field" for="create-cpu"><span>CPU capacity</span><input id="create-cpu" name="cpu" type="number" value="1" min="0.01" step="any" required /><small>Fractional requests round up to whole vCPUs.</small></label><label class="field" for="create-ram"><span>Memory</span><input id="create-ram" name="ram" type="text" value="512M" required /><small>At least 128 MiB. Try 512M, 1G, or 2G.</small></label></div></section>
+            <section class="soft-panel form-section"><label class="field" for="create-storage"><span>Private storage</span><input id="create-storage" name="storage" type="text" value="30G" required /><small>Minimum 30 GiB. Try 30G, 50G, or 1T. You can resize this disk later.</small></label></section>
             <section class="soft-panel form-section"><header class="section-heading"><div><h2><span class="step-number">02</span>A way to connect</h2><span>Private networking and guest access.</span></div></header><label class="field" for="create-guest-ip"><span>Guest IPv4 address <small>Optional</small></span><input id="create-guest-ip" name="guest_ip" type="text" placeholder="Automatically assigned" autocomplete="off" /></label><div class="form-grid"><label class="field" for="create-username"><span>Guest user</span><input id="create-username" name="username" type="text" value="root" autocomplete="username" required /></label><label class="field" for="create-password"><span>Guest password</span><span class="password-field"><input id="create-password" name="password" type="password" value="root" autocomplete="new-password" maxlength="128" required /><button class="icon-button" type="button" data-action="toggle-password" aria-label="Show password" aria-pressed="false"><svg class="icon"><use href="#i-eye"/></svg></button></span></label></div><p class="panel-footnote">Use an account that exists in your guest image. Credentials are applied to the machine’s private disk.</p></section>
             <section class="soft-panel form-section"><header class="section-heading"><div><h2><span class="step-number">03</span>Open the right doors</h2><span>Choose which private TCP services are allowed.</span></div></header><label class="toggle-field"><span><strong>Include the default SSH rule</strong><small>Allow TCP port 22 for terminal access.</small></span><input id="create-default-ssh" name="default_ssh" type="checkbox" checked /><span class="toggle-track" aria-hidden="true"></span></label><label class="field" for="create-ports"><span>Additional port rules <small>Optional</small></span><input id="create-ports" name="ports" type="text" placeholder="80:HTTP, 443:HTTPS" spellcheck="false" /><small>Separate rules with commas. HTTP and HTTPS both use TCP.</small></label></section></div>
             <aside class="create-summary soft-panel"><div class="summary-art" aria-hidden="true"><div></div><div></div><span><svg class="icon"><use href="#i-server"/></svg></span></div><span class="subtle-label">Your next little machine</span><h2 id="create-summary-name">Room for an idea.</h2><p>A private disk, a network identity,<br />and a fresh start.</p><dl id="create-summary-details" class="detail-list"></dl><p id="create-error" class="form-error" role="alert"></p><button id="create-submit" class="button button-primary button-wide" type="submit"><span>Create machine</span><svg class="icon"><use href="#i-arrow"/></svg></button><a href="#vms" class="quiet-link summary-cancel">Maybe later</a><span class="summary-note"><svg class="icon"><use href="#i-spark"/></svg>Built on Firecracker</span></aside>

uvm/dashboard/static/js/dashboard.js

@@ -27,6 +27,7 @@
     detailId: null,
     detail: null,
     portEditing: false,
+    resizeEditing: false,
     selected: new Set(),
     filter: 'all',
     query: '',
@@ -86,6 +87,10 @@
     return mib >= 1024 ? `${number(mib / 1024)} GiB` : `${number(mib)} MiB`;
   }
 
+  function formatStorage(value) {
+    return value == null ? 'Not recorded' : formatRam(value);
+  }
+
   function timestamp(value) {
     if (value == null || value === '') return NaN;
     if (typeof value === 'number' || /^\d+(\.\d+)?$/.test(value)) {
@@ -396,7 +401,7 @@
       return `<tr class="${state.selected.has(vm.id) ? 'selected' : ''}">
         <td class="check-cell"><input type="checkbox" data-select="${id}" aria-label="Select ${esc(machineName(vm))}" ${state.selected.has(vm.id) ? 'checked' : ''} /></td>
         <td><div class="machine-name"><span class="round-icon">${icon('server')}</span><div><a href="${esc(vmHref(vm.id))}" title="${esc(machineName(vm))}">${esc(machineName(vm))}</a><small>${esc(vm.guest_ip || vm.id)}</small></div></div></td>
-        <td>${badge(runtimeStatus(vm))}</td><td class="allocation-cell">${vcpu(vm)} vCPU<small>${esc(formatRam(vm.ram_mib))}</small></td>
+        <td>${badge(runtimeStatus(vm))}</td><td class="allocation-cell">${vcpu(vm)} vCPU<small>${esc(formatRam(vm.ram_mib))} RAM</small><small>${esc(formatStorage(vm.storage_mib))} storage</small></td>
         <td><div class="table-ports">${portsMarkup(vm.ports, 2)}</div></td><td>${badge(vm.policy_status || 'unknown')}</td>
         <td><div class="row-controls"><button class="icon-button" type="button" data-action="vm-action" data-operation="${running ? 'stop' : 'start'}" data-id="${id}" aria-label="${running ? 'Stop' : 'Start'} ${esc(machineName(vm))}" title="${running ? 'Stop' : 'Start'} machine" ${busy ? 'disabled' : ''}>${icon(running ? 'stop' : 'play')}</button><button class="icon-button" type="button" data-action="machine-menu" data-id="${id}" aria-label="Actions for ${esc(machineName(vm))}" aria-haspopup="menu" aria-expanded="false">${icon('more')}</button></div></td>
       </tr>`;
@@ -598,7 +603,7 @@
       : actionButton('start', 'Start machine', 'play', true));
     html('#detail-config', detailRows([
       ['Recorded state', label(vm.status)], ['Observed state', label(runtimeStatus(vm))],
-      ['vCPUs', vcpu(vm)], ['Memory', formatRam(vm.ram_mib)], ['Guest user', vm.username],
+      ['vCPUs', vcpu(vm)], ['Memory', formatRam(vm.ram_mib)], ['Storage', formatStorage(vm.storage_mib)], ['Guest user', vm.username],
       ['Created', formatDate(vm.created_at)], ['Last updated', formatDate(vm.updated_at)],
     ]));
     html('#detail-network', detailRows([
@@ -625,6 +630,19 @@
     $('#sync-ports-btn').disabled = busy;
     $('#open-ports-btn').hidden = vm.ports === null;
     $('#close-ports-btn').hidden = vm.ports === null;
+    if (!state.resizeEditing) {
+      const resources = vm.pending_resize || vm;
+      $('#resize-cpu').value = resources.cpu;
+      $('#resize-ram').value = `${resources.ram_mib}M`;
+      $('#resize-storage').value = resources.storage_mib == null ? '' : `${resources.storage_mib / 1024}G`;
+    }
+    $('#resize-form').hidden = !state.resizeEditing;
+    $('#edit-resources-btn').hidden = state.resizeEditing;
+    $('#edit-resources-btn').disabled = busy || runtimeStatus(vm) === 'unknown' || vm.ports === null || vm.operation === 'delete' || vm.status === 'terminating';
+    $('#resize-submit').disabled = busy;
+    text('#resize-note', vm.pending_resize
+      ? `Pending resize: ${number(vm.pending_resize.cpu)} CPU, ${formatRam(vm.pending_resize.ram_mib)} memory, ${formatStorage(vm.pending_resize.storage_mib)} storage. Retry the resize or start the stopped machine to finish it.`
+      : 'Resource changes stop the machine, apply the new size, and start it again with its existing IP and guest credentials.');
   }
 
   async function loadDetail(identifier) {
@@ -756,6 +774,67 @@
     return mib;
   }
 
+  function parseStorage(value) {
+    const match = value.trim().match(/^(\d+(?:\.\d+)?)\s*([BKMGT]i?B?)?$/i);
+    if (!match) throw new Error('Use a storage amount such as 30G, 50G, or 1T.');
+    const factors = { b: 1 / (1024 * 1024), k: 1 / 1024, kb: 1 / 1024, ki: 1 / 1024, kib: 1 / 1024, m: 1, mb: 1, mi: 1, mib: 1, g: 1024, gb: 1024, gi: 1024, gib: 1024, t: 1024 * 1024, tb: 1024 * 1024, ti: 1024 * 1024, tib: 1024 * 1024 };
+    const amount = Number(match[1]) * factors[(match[2] || 'g').toLowerCase()];
+    if (!Number.isFinite(amount) || amount < 30 * 1024) throw new Error('Give this machine at least 30 GiB of storage.');
+    if (amount > 8796093022207) throw new Error('That storage capacity exceeds the supported limit.');
+    return Math.ceil(amount);
+  }
+
+  async function submitResize(event) {
+    event.preventDefault();
+    if (!state.detail || state.busy.has(state.detail.id)) return;
+    const id = state.detail.id;
+    const session = state.session;
+    const payload = {};
+    try {
+      const cpu = $('#resize-cpu').value.trim();
+      const ram = $('#resize-ram').value.trim();
+      const storage = $('#resize-storage').value.trim();
+      if (cpu) {
+        payload.cpu = Number(cpu);
+        if (!Number.isFinite(payload.cpu) || payload.cpu <= 0) throw new Error('CPU capacity must be a positive number.');
+      }
+      if (ram) { parseRam(ram); payload.ram = ram; }
+      if (storage) { parseStorage(storage); payload.storage = storage; }
+      if (!Object.keys(payload).length) throw new Error('Enter at least one resource to resize.');
+    } catch (error) {
+      text('#resize-error', error.message);
+      return;
+    }
+    text('#resize-error', '');
+    const button = $('#resize-submit');
+    const previous = button.textContent;
+    const unlock = lockForm($('#resize-form'));
+    state.busy.add(id);
+    button.textContent = 'Resizing and restarting…';
+    renderDetail();
+    try {
+      await api(vmPath(id, '/resize'), { method: 'POST', body: payload });
+      if (session !== state.session) return;
+      if (state.detailId === id) state.resizeEditing = false;
+      toast('Machine resized and started.');
+      await refreshAfterMutation(id);
+    } catch (error) {
+      if (!isAborted(error) && session === state.session) {
+        if (state.detailId === id) text('#resize-error', error.message);
+        else toast(error.message, true);
+        await refreshAfterMutation(id);
+      }
+    } finally {
+      unlock();
+      button.textContent = previous;
+      if (session === state.session) {
+        state.busy.delete(id);
+        renderMachines();
+        renderDetail();
+      }
+    }
+  }
+
   async function submitPorts(event) {
     event.preventDefault();
     if (!state.detail || state.busy.has(state.detail.id)) return;
@@ -810,8 +889,10 @@
 
   function updateCreateSummary() {
     let memory = '—';
+    let storage = '—';
     let ports = 'Check port rules';
     try { memory = formatRam(parseRam($('#create-ram').value)); } catch { /* The form reports validation on submit. */ }
+    try { storage = formatStorage(parseStorage($('#create-storage').value)); } catch { /* Report invalid capacity on submit. */ }
     try {
       const rules = parsePorts($('#create-ports').value);
       if ($('#create-default-ssh').checked && !rules.some((rule) => rule.port === 22)) rules.unshift({ port: 22, protocol: 'TCP' });
@@ -821,7 +902,7 @@
     text('#create-summary-name', $('#create-name').value.trim() || 'Room for an idea.');
     html('#create-summary-details', detailRows([
       ['Compute', Number.isFinite(cpu) && cpu > 0 ? `${Math.ceil(cpu)} vCPU` : '—'],
-      ['Memory', memory], ['Guest IP', $('#create-guest-ip').value.trim() || 'Automatic'],
+      ['Memory', memory], ['Storage', storage], ['Guest IP', $('#create-guest-ip').value.trim() || 'Automatic'],
       ['Guest user', $('#create-username').value.trim() || '—'], ['Allowed ports', ports],
     ]));
     const presets = { small: [1, 512], balanced: [2, 1024], roomy: [4, 2048] };
@@ -849,12 +930,14 @@
     let payload;
     try {
       parseRam($('#create-ram').value);
+      parseStorage($('#create-storage').value);
       const cpu = Number($('#create-cpu').value);
       if (!Number.isFinite(cpu) || cpu <= 0) throw new Error('CPU capacity must be a positive number.');
       payload = {
         name: $('#create-name').value.trim() || null,
         cpu,
         ram: $('#create-ram').value.trim(),
+        storage: $('#create-storage').value.trim(),
         guest_ip: $('#create-guest-ip').value.trim() || null,
         username: $('#create-username').value.trim(),
         password: $('#create-password').value,
@@ -1048,6 +1131,8 @@
     state.detailId = identifier;
     state.detail = null;
     state.portEditing = false;
+    state.resizeEditing = false;
+    text('#resize-error', '');
     closeMenu();
     closeSearch();
     setMobileNav(false);
@@ -1156,6 +1241,7 @@
     state.detail = null;
     state.detailId = null;
     state.portEditing = false;
+    state.resizeEditing = false;
     state.query = '';
     state.filter = 'all';
     state.sort = 'recent';
@@ -1176,6 +1262,7 @@
     $('#token-input').disabled = false;
     text('#create-error', '');
     text('#port-error', '');
+    text('#resize-error', '');
     text('#auth-error', message);
     $('#main-app').hidden = true;
     $('#auth-screen').hidden = false;
@@ -1209,6 +1296,13 @@
       $('#port-input').focus();
     }
     if (action === 'cancel-ports') { state.portEditing = false; text('#port-error', ''); renderDetail(); }
+    if (action === 'edit-resources') {
+      state.resizeEditing = true;
+      text('#resize-error', '');
+      renderDetail();
+      $('#resize-cpu').focus();
+    }
+    if (action === 'cancel-resize') { state.resizeEditing = false; text('#resize-error', ''); renderDetail(); }
     if (action === 'toggle-password') {
       const visible = $('#create-password').type === 'password';
       $('#create-password').type = visible ? 'text' : 'password';
@@ -1224,6 +1318,7 @@
     $('#create-form').addEventListener('submit', submitCreate);
     $('#create-form').addEventListener('input', updateCreateSummary);
     $('#port-editor').addEventListener('submit', submitPorts);
+    $('#resize-form').addEventListener('submit', submitResize);
     $('#bulk-run-btn').addEventListener('click', runBulkAction);
     $('#log-tail').addEventListener('change', loadLogs);
     $('#vm-search').addEventListener('input', (event) => { state.query = event.target.value; renderMachines(); });

uvm/images.py

@@ -112,6 +112,13 @@ class ImageStore:
             raise
         return destination
 
+    def disk_size_bytes(self, disk: Path) -> int:
+        """Read logical disk capacity, including a resize published before state was saved."""
+        try:
+            return disk.stat().st_size
+        except OSError as error:
+            raise UvmError(f"could not inspect private disk capacity: {disk}: {error}") from error
+
     def resize_vm_disk(self, disk: Path, storage_mib: int) -> None:
         """Resize a proven-offline private disk on a copy, then publish atomically."""
         self._validate_storage(storage_mib)

uvm/known_hosts.py

@@ -0,0 +1,167 @@
+"""Remove a deleted VM's entries from local OpenSSH host-key caches."""
+
+from __future__ import annotations
+
+import base64
+import binascii
+import fcntl
+import hmac
+import os
+import pwd
+import re
+import stat
+import uuid
+from ipaddress import IPv4Address
+from pathlib import Path
+
+from .config import Settings
+from .domain import VmRecord
+from .errors import UvmError
+
+
+_HOST_LINE = re.compile(
+    rb"^[ \t]*(?:@(?:cert-authority|revoked)[ \t]+)?"
+    rb"(?P<hosts>[^ \t\r\n]+)[ \t]+[^ \t\r\n]+[ \t]+[^ \t\r\n]+"
+)
+_PORT_HOST = re.compile(rb"\[([^\]]+)\]:(\d+)\Z")
+
+
+class KnownHostsManager:
+    """Deletion-only cleanup; lifecycle owns the lock and confirms VM teardown."""
+
+    def __init__(self, settings: Settings) -> None:
+        self._settings = settings
+
+    def remove(self, vm: VmRecord) -> None:
+        try:
+            address = str(IPv4Address(vm.guest_ip)).encode("ascii")
+        except ValueError as error:
+            raise UvmError("known_hosts cleanup requires a valid guest IPv4 address") from error
+        if re.fullmatch(r"[A-Za-z0-9][A-Za-z0-9_.-]{0,80}", vm.id) is None:
+            raise UvmError("known_hosts cleanup requires a valid VM ID")
+        alias = f"uvm-{vm.id}".encode("ascii")
+        hosts = {address, alias, alias.lower()}
+        ports = {22, *(rule.port for rule in vm.ports or ())}
+        hashed_candidates = hosts | {
+            b"[" + host + b"]:" + str(port).encode("ascii") for host in hosts for port in ports
+        }
+        for path, owner in self._files().items():
+            self._remove_file(path, hosts, hashed_candidates, owner)
+
+    def _files(self) -> dict[Path, int | None]:
+        if self._settings.known_hosts_files is not None:
+            return dict.fromkeys(self._settings.known_hosts_files)
+        try:
+            effective_uid = os.geteuid()
+            accounts = [pwd.getpwuid(effective_uid)]
+            if effective_uid == 0:
+                sudo_uid = os.environ.get("SUDO_UID")
+                sudo_user = os.environ.get("SUDO_USER")
+                if sudo_uid:
+                    if not sudo_uid.isascii() or not sudo_uid.isdigit():
+                        raise ValueError("invalid SUDO_UID")
+                    accounts.append(pwd.getpwuid(int(sudo_uid)))
+                elif sudo_user:
+                    accounts.append(pwd.getpwnam(sudo_user))
+            return {
+                Path(account.pw_dir) / ".ssh" / filename: account.pw_uid
+                for account in accounts for filename in ("known_hosts", "known_hosts2")
+            }
+        except (KeyError, ValueError, OverflowError) as error:
+            raise UvmError("could not determine SSH user homes; configure UVM_KNOWN_HOSTS_FILES") from error
+
+    @staticmethod
+    def _remove_file(path: Path, hosts: set[bytes], candidates: set[bytes], owner: int | None) -> None:
+        directory = None
+        temporary = None
+        try:
+            # Pin the directory and reject symlink/FIFO/hard-link targets when
+            # editing another local user's cache from a privileged process.
+            try:
+                directory = os.open(path.parent, os.O_RDONLY | os.O_DIRECTORY | os.O_NOFOLLOW)
+                descriptor = os.open(path.name, os.O_RDONLY | os.O_NOFOLLOW | os.O_NONBLOCK, dir_fd=directory)
+            except FileNotFoundError:
+                return
+            with os.fdopen(descriptor, "rb") as source:
+                metadata = os.fstat(source.fileno())
+                if not stat.S_ISREG(metadata.st_mode) or metadata.st_nlink != 1:
+                    raise UvmError(f"known_hosts must be a regular, single-link file: {path}")
+                if owner is not None and metadata.st_uid != owner:
+                    raise UvmError(f"known_hosts has an unexpected owner: {path}")
+                fcntl.flock(source.fileno(), fcntl.LOCK_EX)
+                metadata = os.fstat(source.fileno())
+                contents = source.read()
+                updated = _without_hosts(contents, hosts, candidates)
+                if updated == contents:
+                    return
+
+                candidate = f".{path.name}.uvm-{uuid.uuid4().hex}"
+                descriptor = os.open(candidate, os.O_WRONLY | os.O_CREAT | os.O_EXCL, 0o600, dir_fd=directory)
+                temporary = candidate
+                with os.fdopen(descriptor, "wb") as output:
+                    output.write(updated)
+                    output.flush()
+                    created = os.fstat(output.fileno())
+                    if (created.st_uid, created.st_gid) != (metadata.st_uid, metadata.st_gid):
+                        os.fchown(output.fileno(), metadata.st_uid, metadata.st_gid)
+                    os.fchmod(output.fileno(), stat.S_IMODE(metadata.st_mode))
+                    for attribute in os.listxattr(source.fileno()):
+                        os.setxattr(output.fileno(), attribute, os.getxattr(source.fileno(), attribute))
+                    os.fsync(output.fileno())
+
+                current = os.stat(path.name, dir_fd=directory, follow_symlinks=False)
+                fields = ("st_dev", "st_ino", "st_size", "st_mtime_ns", "st_ctime_ns", "st_mode", "st_uid", "st_gid", "st_nlink")
+                if any(getattr(current, field) != getattr(metadata, field) for field in fields):
+                    raise UvmError(f"known_hosts changed during cleanup; retry deletion: {path}")
+                os.replace(temporary, path.name, src_dir_fd=directory, dst_dir_fd=directory)
+                os.fsync(directory)
+        except OSError as error:
+            raise UvmError(f"could not clean SSH known_hosts {path}: {error}") from error
+        finally:
+            if directory is not None:
+                try:
+                    if temporary is not None:
+                        try:
+                            os.unlink(temporary, dir_fd=directory)
+                        except FileNotFoundError:
+                            pass
+                finally:
+                    os.close(directory)
+
+
+def _without_hosts(contents: bytes, hosts: set[bytes], candidates: set[bytes]) -> bytes:
+    """Preserve unrelated aliases, comments, markers, key types, and line endings."""
+    def matches(token: bytes) -> bool:
+        if token.startswith(b"|1|"):
+            try:
+                _, _version, salt_text, digest_text = token.split(b"|")
+                salt = base64.b64decode(salt_text, validate=True)
+                digest = base64.b64decode(digest_text, validate=True)
+            except (ValueError, binascii.Error):
+                return False
+            return len(salt) == len(digest) == 20 and any(
+                hmac.compare_digest(digest, hmac.digest(salt, candidate, "sha1")) for candidate in candidates
+            )
+        token = token.lower()
+        if token in hosts:
+            return True
+        bracketed = _PORT_HOST.fullmatch(token)
+        return (bracketed is not None and bracketed[1] in hosts
+                and len(bracketed[2]) <= 5 and 1 <= int(bracketed[2]) <= 65535)
+
+    retained = []
+    for line in contents.splitlines(keepends=True):
+        if line.lstrip().startswith(b"#"):
+            retained.append(line)
+            continue
+        match = _HOST_LINE.match(line)
+        if match is None:
+            retained.append(line)
+            continue
+        names = match["hosts"].split(b",")
+        remaining = [name for name in names if not matches(name)]
+        if remaining == names:
+            retained.append(line)
+        elif remaining:
+            retained.append(line[:match.start("hosts")] + b",".join(remaining) + line[match.end("hosts"):])
+    return b"".join(retained)

uvm/lifecycle.py

@@ -19,6 +19,7 @@ from .firecracker.config import build_config, write_config
 from .firecracker.process import FirecrackerProcessManager, ProcessInfo
 from .images import ImageStore
 from .integrity import load_manifest, verify_file
+from .known_hosts import KnownHostsManager
 from .network import NetworkManager
 from .state import StateStore
 from .system import check_kvm, ensure_data_directories, require_root
@@ -55,6 +56,7 @@ class LifecycleService:
     def __init__(
         self, settings: Settings, state_store: StateStore, images: ImageStore,
         network: NetworkManager, process: FirecrackerProcessManager, *,
+        known_hosts: KnownHostsManager,
         client_factory: Callable[[Path, float], FirecrackerClient] = FirecrackerClient,
         clock: Callable[[], float] = time.time,
     ) -> None:
@@ -63,6 +65,7 @@ class LifecycleService:
         self._images = images
         self._network = network
         self._process = process
+        self._known_hosts = known_hosts
         self._client_factory = client_factory
         self._clock = clock
 
@@ -251,7 +254,7 @@ class LifecycleService:
             previous = vm.pending_resize
             capacity = previous.storage_mib if previous is not None else vm.storage_mib
             if capacity is None:
-                capacity = max(MIN_STORAGE_MIB, (Path(vm.disk).stat().st_size + 1024 * 1024 - 1) // (1024 * 1024))
+                capacity = max(MIN_STORAGE_MIB, (self._images.disk_size_bytes(Path(vm.disk)) + 1024 * 1024 - 1) // (1024 * 1024))
             vm.pending_resize = VmResources(
                 cpu=cpu if cpu is not None else previous.cpu if previous is not None else vm.cpu,
                 ram_mib=ram_mib if ram_mib is not None else previous.ram_mib if previous is not None else vm.ram_mib,
@@ -284,7 +287,11 @@ class LifecycleService:
             return
         if self._process.observe(vm) != "gone":
             raise ConflictError("cannot resize a disk without confirmed process exit")
-        if target.storage_mib != vm.storage_mib:
+        # A prior attempt may have published a resized image without saving
+        # its allocation. Check the disk too, including when a retry changes
+        # the target back to the previously recorded capacity.
+        if (target.storage_mib != vm.storage_mib
+                or self._images.disk_size_bytes(Path(vm.disk)) != target.storage_mib * 1024 * 1024):
             self._images.resize_vm_disk(Path(vm.disk), target.storage_mib)
         vm.cpu, vm.ram_mib, vm.storage_mib = target.cpu, target.ram_mib, target.storage_mib
         vm.pending_resize = None
@@ -301,6 +308,7 @@ class LifecycleService:
         try:
             self._cleanup_runtime(vm, timeout=timeout)
             self._remove_runtime(vm)
+            self._known_hosts.remove(vm)
             self._remove_record(vm.id)
             return vm
         except BaseException as error: