fix(sftp): use remote cp for fresh same-host copies (Fixes #4207) (#4226)

* fix(sftp): use remote cp for fresh same-host copies (Fixes #4207)

Ordinary SFTP tasks were marked resumable, which skipped the existing file and directory cp optimizations. Select the non-resumable route only when creating fresh matching-host copies with eligible encodings, keeping transfer-center rows and recursive children consistent. Existing checkpointed transfers retain their saved resumable path; failed cp attempts retain the download/upload fallback.

* fix(sftp): skip same-host directory cp when auto encoding resolves to non-UTF-8

* fix(sftp): preserve dest mode when same-host cp replaces a file

* fix(sftp): skip same-host cp for symlinks and directory merges

* test(sftp): mock missing dest in same-host cp cache fixture

* fix(sftp): expose lstat on session-backed copy clients

application/state/sftp/useSftpTransfers.transferPlan.test.tsx

@@ -6,6 +6,7 @@ import { act, create, type ReactTestRenderer } from "react-test-renderer";
 import { PREFLIGHT_STAT_CONCURRENCY, PREFLIGHT_STAT_MAX_FILES, useSftpTransfers } from "./useSftpTransfers";
 import { sftpTransferCenterStore } from "../sftpTransferCenterStore";
 import type { SftpPane } from "./types";
+import { buildCacheKey } from "./sharedRemoteHostCache";
 
 for (const direction of ["download", "upload"] as const) {
 test(`failed ${direction} connection replaces Waiting with the actual error (#3698)`, async () => {
@@ -999,3 +1000,86 @@ test("no-conflict local copy awaits discovery so a late stat cannot overwrite th
     restore();
   }
 });
+
+for (const scenario of ["folder-cp", "folder-fallback", "file-cp", "different-key", "missing-key", "non-utf8"] as const) {
+  test(`fresh remote copy selects a consistent strategy: ${scenario} (#4207)`, async () => {
+    const isDirectory = scenario.startsWith("folder");
+    const source = makePane("left");
+    const target = makePane("left");
+    target.connection = { ...target.connection!, id: "target-conn", currentPath: "/usr/tmp" };
+    if (scenario === "non-utf8") target.filenameEncoding = "gb18030";
+    const key = buildCacheKey("host-1", "debian", 22, "ssh", false, "user", "sftp");
+    const keys = new Map([["remote-conn", key], ["target-conn", key]]);
+    if (scenario === "different-key") keys.set("target-conn", buildCacheKey("host-2", "debian", 22, "ssh", false, "user", "sftp"));
+    if (scenario === "missing-key") keys.delete("target-conn");
+    const ownerId = `same-host-${scenario}-4207`;
+    const streams: Array<{ resumable: boolean; sameHost?: boolean; parentTaskId?: string }> = [];
+    const copies: unknown[][] = [];
+    let listings = 0;
+    let ops: ReturnType<typeof useSftpTransfers> | undefined;
+    let renderer: ReactTestRenderer | undefined;
+    const restore = installGlobals({
+      statSftp: async (id: string) => id === "sftp-source"
+        ? { type: "file", size: 3626, lastModified: 1758000001000 }
+        : null,
+      mkdirSftp: async () => undefined,
+      sameHostCopyDirectory: async (...args: unknown[]) => {
+        copies.push(args);
+        assert.equal(sftpTransferCenterStore.getTask(args[4] as string)?.resumable, false);
+        return { success: scenario !== "folder-fallback" };
+      },
+      startStreamTransfer: async (options: { transferId: string; resumable: boolean; sameHost?: boolean; parentTaskId?: string }) => {
+        streams.push(options);
+        assert.equal(sftpTransferCenterStore.getTask(options.transferId)?.resumable, options.resumable);
+        sftpTransferCenterStore.ingestBackgroundEvent({
+          type: "completed", transferId: options.transferId,
+          transferred: 3626, totalBytes: 3626, lifecycleEpoch: 0,
+        });
+        return {};
+      },
+    });
+    function Probe() {
+      ops = useSftpTransfers({
+        ownerId,
+        getActivePane: (side) => side === "left" ? source : target,
+        getPaneByConnectionId: () => null,
+        getTabByConnectionId: () => null,
+        updateTab: () => undefined,
+        refresh: async () => undefined,
+        clearCacheForConnection: () => undefined,
+        handleSessionError: () => undefined,
+        sftpSessionsRef: { current: new Map([["remote-conn", "sftp-source"], ["target-conn", "sftp-target"]]) },
+        connectionCacheKeyMapRef: { current: keys },
+        listLocalFiles: async () => [],
+        listRemoteFiles: async () => { listings++; return source.files; },
+      });
+      return null;
+    }
+    try {
+      await act(async () => { renderer = create(React.createElement(Probe)); });
+      await act(async () => {
+        const results = await ops!.startTransfer(
+          [{ name: isDirectory ? "bt_mine" : "aops_dns_view_demo.sh", isDirectory }], "left", "right",
+        );
+        assert.equal(results[0]?.status, "completed");
+      });
+      const eligible = ["folder-cp", "folder-fallback", "file-cp"].includes(scenario);
+      const rows = sftpTransferCenterStore.getOwnerTasks(ownerId);
+      assert.ok(rows.length > 0);
+      assert.ok(rows.every(row => row.resumable === !eligible));
+      assert.equal(copies.length, isDirectory ? 1 : 0);
+      if (isDirectory) assert.deepEqual(copies[0]?.slice(0, 4), ["sftp-source", "/opt/bt_mine", "/usr/tmp/bt_mine", "auto"]);
+      assert.equal(listings, scenario === "folder-fallback" ? 1 : 0);
+      assert.equal(streams.length, scenario === "folder-cp" ? 0 : 1);
+      if (streams.length) {
+        assert.equal(streams[0].resumable, !eligible);
+        assert.equal(streams[0].sameHost, !["different-key", "missing-key"].includes(scenario) || undefined);
+        if (isDirectory) assert.ok(streams[0].parentTaskId);
+      }
+    } finally {
+      await act(async () => { renderer?.unmount(); });
+      for (const row of sftpTransferCenterStore.getOwnerTasks(ownerId)) sftpTransferCenterStore.dismiss(row.id);
+      restore();
+    }
+  });
+}

application/state/sftp/useSftpTransfers.ts

@@ -1348,6 +1348,17 @@ export const useSftpTransfers = ({
       const sourceConnectionId = options?.sourceConnectionId ?? sourcePane.connection.id;
       const batchId = crypto.randomUUID();
       const usesLegacyScp = sourcePane.connection.fileProtocol === "scp" || targetPane.connection.fileProtocol === "scp";
+      const sourceCacheKey = connectionCacheKeyMapRef.current.get(sourcePane.connection.id);
+      const targetCacheKey = connectionCacheKeyMapRef.current.get(targetPane.connection.id);
+      const encodingSafeForExec = [sourcePane.filenameEncoding, targetPane.filenameEncoding]
+        .every((encoding) => !encoding || encoding === "utf-8" || encoding === "auto");
+      // Select the existing non-resumable cp route only for newly created copies.
+      // Resume/recovery keeps its saved strategy and checkpoints. If cp fails,
+      // recursive/download+upload fallback also remains non-resumable.
+      const useSameHostCopy = !usesLegacyScp
+        && !sourcePane.connection.isLocal && !targetPane.connection.isLocal
+        && !!sourceCacheKey && sourceCacheKey === targetCacheKey
+        && encodingSafeForExec;
 
       const newTasks: TransferTask[] = [];
       const skippedResults: TransferResult[] = [];
@@ -1582,8 +1593,10 @@ export const useSftpTransfers = ({
           sourceLastModified,
           preflightStatSkipped: preflightSkippedNames.has(file.name),
           origin: "manual",
-          resumable: !usesLegacyScp,
-          pauseUnavailableReason: usesLegacyScp ? "This server uses legacy SCP; cancel and retry from the beginning instead" : undefined,
+          resumable: !usesLegacyScp && !useSameHostCopy,
+          pauseUnavailableReason: usesLegacyScp
+            ? "This server uses legacy SCP; cancel and retry from the beginning instead"
+            : useSameHostCopy ? "Same-host copies cannot be paused; cancel and retry from the beginning instead" : undefined,
           phase: file.isDirectory ? "scanning" : "transferring",
         });
       }

components/settings/tabs/SettingsFileAssociationsTab.test.ts

@@ -9,6 +9,13 @@ test("SFTP settings imports the shared Toggle used by its option rows", () => {
   assert.match(source, /Toggle,\s*\n\s*Select,/);
 });
 
+test("folder compression row exposes its settings search anchor", () => {
+  assert.match(
+    source,
+    /<SettingRow\s+anchorId="sftp-compressed-upload"\s+label=\{t\('settings\.sftp\.compressedUpload\.enable'\)\}/,
+  );
+});
+
 function functionBody(functionName: string): string {
   const start = source.indexOf(`const ${functionName} = useCallback`);
   assert.notEqual(start, -1, `${functionName} should exist`);

components/settings/tabs/SettingsFileAssociationsTab.tsx

@@ -180,6 +180,7 @@ export default function SettingsFileAssociationsTab() {
       <SectionHeader title={t('settings.sftp.compressedUpload')} />
       <SettingCard>
         <SettingRow
+          anchorId="sftp-compressed-upload"
           label={t('settings.sftp.compressedUpload.enable')}
           description={t('settings.sftp.compressedUpload.enableDesc')}
         >
@@ -231,12 +232,14 @@ export default function SettingsFileAssociationsTab() {
           </div>
         </SettingRow>
         <SettingRow
+          anchorId="sftp-skip-unchanged"
           label={t('settings.sftp.skipUnchanged.enable')}
           description={t('settings.sftp.skipUnchanged.enableDesc')}
         >
           <Toggle checked={sftpSkipUnchanged} onChange={setSftpSkipUnchanged} />
         </SettingRow>
         <SettingRow
+          anchorId="sftp-transport-idle-ttl"
           label={t('settings.ssh.transportIdleTtl')}
           description={t('settings.ssh.transportIdleTtl.desc')}
         >

components/sftp/localFileDrag.interaction.test.ts

@@ -75,6 +75,9 @@ test('list hook preserves local copy/move routing, remote HTML drag, selection a
     await act(async () => root.render(React.createElement(Harness, { local: false })));
     await act(async () => right.handlePaneDrop(event()));
     assert.equal(actions.at(-1)?.kind, 'copy');
+    actions.length = 0;
+    await act(async () => left.handleEntryDrop(entries[2], event()));
+    assert.deepEqual(actions, [{ kind: 'move', args: [['/files/b.txt'], '/files/folder'] }], 'same-pane remote drag stays a move');
   } finally {
     await act(async () => root.unmount());
     clearLocalFileDrag();

domain/knownHosts.test.ts

@@ -1,6 +1,11 @@
 import test from "node:test";
 import assert from "node:assert/strict";
 import crypto from "node:crypto";
+import { createRequire } from "node:module";
+
+const require = createRequire(import.meta.url);
+const { describeHostKey } = require("../electron/bridges/hostKeyVerifier.cjs");
+const { mintHostCertificates, legacyCertificate, sshString, sshKeygenSkip } = require("../electron/bridges/fixtures/hostCertificates.test.fixture.cjs");
 
 import type { KnownHost } from "./models";
 import {
@@ -139,6 +144,55 @@ test("fingerprintFromPublicKey returns empty string on missing input", () => {
 
 // --- Migration --------------------------------------------------------------
 
+for (const options of [
+  { type: "ed25519" },
+  { type: "rsa", bits: 2048 },
+  ...[256, 384, 521].map((bits) => ({ type: "ecdsa", bits })),
+  { type: "ed25519", sk: true },
+  { type: "ecdsa", bits: 256, sk: true },
+]) {
+  test(`renderer certificate fingerprint and migration agree with verifier: ${JSON.stringify(options)}`, { skip: sshKeygenSkip }, (t) => {
+    const { first, renewed, different } = mintHostCertificates(t, options);
+    const expected = describeHostKey(first.blob).fingerprint;
+    assert.equal(fingerprintFromPublicKey(first.line), expected);
+    assert.equal(expected, first.publicKeyFingerprint);
+    assert.equal(fingerprintFromPublicKey(renewed.line), expected);
+    assert.notEqual(fingerprintFromPublicKey(different.line), expected);
+    assert.equal(fingerprintFromPublicKey(first.plain.line), expected);
+
+    const legacy = knownHost({
+      keyType: first.keyType,
+      publicKey: first.line,
+      fingerprint: crypto.createHash("sha256").update(first.blob).digest("base64").replace(/=+$/g, ""),
+    });
+    const migrated = normalizeKnownHost(legacy);
+    assert.equal(migrated.fingerprint, expected);
+    assert.equal(migrated.keyType, first.keyType);
+    assert.equal(migrated.publicKey, first.line);
+    assert.equal(normalizeKnownHost(migrated), migrated, "migration is idempotent");
+    assert.equal(normalizeKnownHost({ ...legacy, fingerprint: undefined }).fingerprint, expected);
+    assert.equal(normalizeKnownHost({ ...legacy, keyType: "" }).keyType, first.keyType);
+    const unrelated = { ...legacy, fingerprint: "unrelated-explicit-fingerprint" };
+    assert.equal(normalizeKnownHost(unrelated), unrelated);
+    const opaque = { ...legacy, publicKey: `SHA256:${legacy.fingerprint}` };
+    assert.equal(normalizeKnownHost(opaque), opaque);
+    const fingerprintOnly = { ...legacy, publicKey: undefined };
+    assert.equal(normalizeKnownHost(fingerprintOnly), fingerprintOnly);
+  });
+}
+
+test("renderer fingerprints v00 certificates and falls back for unparseable certificates", () => {
+  const cert = legacyCertificate("ssh-rsa", ["exponent", "modulus"]);
+  assert.equal(fingerprintFromPublicKey(cert.line), describeHostKey(cert.plain).fingerprint);
+  const malformed = Buffer.concat([
+    sshString("ssh-ed25519-cert-v01@openssh.com"), sshString("nonce"), sshString(Buffer.alloc(32)),
+  ]);
+  const line = `ssh-ed25519-cert-v01@openssh.com ${malformed.toString("base64")}`;
+  const fullHash = crypto.createHash("sha256").update(malformed).digest("base64").replace(/=+$/g, "");
+  assert.equal(fingerprintFromPublicKey(line), fullHash);
+  assert.equal(fingerprintFromPublicKey(line), describeHostKey(malformed).fingerprint);
+});
+
 test("normalizeKnownHost backfills fingerprint when only publicKey is stored", () => {
   const rawKey = makeRawPublicKey("ssh-ed25519");
   const base64Body = rawKey.toString("base64");

domain/knownHosts.ts

@@ -1,4 +1,5 @@
 import type { KnownHost } from "./models";
+import { extractCertificatePublicKey } from "@/domain/sshPublicKey.shared.cjs";
 
 const normalizeHost = (value: string) => value.trim().toLowerCase();
 
@@ -132,7 +133,7 @@ export const fingerprintFromPublicKey = (publicKey: string | undefined | null):
   const parts = trimmed.split(/\s+/);
   if (parts.length >= 2 && SSH_KEY_TYPE_PREFIX.test(parts[0])) {
     const bytes = base64Decode(parts[1]);
-    if (bytes) return stripPadding(base64Encode(sha256Bytes(bytes)));
+    if (bytes) return stripPadding(base64Encode(sha256Bytes(extractCertificatePublicKey(bytes) || bytes)));
   }
 
   return stripPadding(trimmed);
@@ -145,9 +146,9 @@ const extractKeyTypeFromPublicKey = (publicKey: string | undefined | null): stri
 };
 
 /**
- * Backfill missing `fingerprint` / `keyType` on a stored record so the host
- * verifier can match it without falling back to the brittle re-derivation
- * path. Returns the same reference when nothing changes so callers can skip
+ * Backfill missing `fingerprint` / `keyType` and migrate full-certificate
+ * fingerprints to the underlying key when the certificate body is available.
+ * Returns the same reference when nothing changes so callers can skip
  * persistence writes and React re-renders.
  */
 export const normalizeKnownHost = (knownHost: KnownHost): KnownHost => {
@@ -156,9 +157,17 @@ export const normalizeKnownHost = (knownHost: KnownHost): KnownHost => {
     && knownHost.keyType.length > 0
     && knownHost.keyType !== "unknown";
 
-  if (hasFingerprint && hasKeyType) return knownHost;
+  const parts = knownHost.publicKey?.trim().split(/\s+/) ?? [];
+  const certBytes = /-cert-v0[01]@openssh\.com$/.test(parts[0]) && parts[1]
+    ? base64Decode(parts[1]) : null;
+  const legacyCertFingerprint = certBytes && extractCertificatePublicKey(certBytes)
+    ? stripPadding(base64Encode(sha256Bytes(certBytes))) : "";
+  const migrateCertificate = legacyCertFingerprint
+    && stripPadding((knownHost.fingerprint ?? "").replace(/^SHA256:/i, "")) === legacyCertFingerprint;
 
-  const derivedFingerprint = hasFingerprint
+  if (hasFingerprint && hasKeyType && !migrateCertificate) return knownHost;
+
+  const derivedFingerprint = hasFingerprint && !migrateCertificate
     ? knownHost.fingerprint!
     : fingerprintFromPublicKey(knownHost.publicKey);
   const derivedKeyType = hasKeyType

domain/settingsSearch.test.ts

@@ -125,6 +125,48 @@ test("settings search finds App Lock from the zh-CN locale", () => {
   assert.ok(hits.some((hit) => hit.entry.id === "system-app-lock"));
 });
 
+test("settings search finds folder compression from the real locales", () => {
+  const tZhReal = (key: string) => zhCN[key] ?? key;
+  const tEnReal = (key: string) => en[key] ?? key;
+  for (const [t, queries] of [
+    [tZhReal, ["压缩", "普通传输"]],
+    [tEnReal, ["compress", "tar"]],
+  ] as const) {
+    for (const query of queries) {
+      const hits = filterSettingsSearchCatalog(query, t);
+      assert.ok(hits.some((hit) => hit.entry.id === "sftp-compressed-upload"), query);
+    }
+  }
+});
+
+test("settings search finds skip unchanged files from the real locales", () => {
+  const tZhReal = (key: string) => zhCN[key] ?? key;
+  const tEnReal = (key: string) => en[key] ?? key;
+  for (const [t, queries] of [
+    [tZhReal, ["跳过未改文件", "修改时间"]],
+    [tEnReal, ["skip unchanged", "rsync"]],
+  ] as const) {
+    for (const query of queries) {
+      const hits = filterSettingsSearchCatalog(query, t);
+      assert.ok(hits.some((hit) => hit.entry.id === "sftp-skip-unchanged"), query);
+    }
+  }
+});
+
+test("settings search finds SSH connection keep-alive from the real locales", () => {
+  const tZhReal = (key: string) => zhCN[key] ?? key;
+  const tEnReal = (key: string) => en[key] ?? key;
+  for (const [t, queries] of [
+    [tZhReal, ["保活时间", "重新认证"]],
+    [tEnReal, ["keep-alive", "re-authentication"]],
+  ] as const) {
+    for (const query of queries) {
+      const hits = filterSettingsSearchCatalog(query, t);
+      assert.ok(hits.some((hit) => hit.entry.id === "sftp-transport-idle-ttl"), query);
+    }
+  }
+});
+
 test("settings search finds temporary network device mode", () => {
   const tEnReal = (key: string) => en[key] ?? key;
   const tZhTW = (key: string) => zhTW[key] ?? key;

domain/settingsSearchCatalog.ts

@@ -671,6 +671,13 @@ export const SETTINGS_SEARCH_CATALOG: readonly SettingsSearchEntry[] = [
     descriptionKey: "settings.sftp.autoSync.enableDesc",
     sectionKey: "settings.sftp.autoSync",
   },
+  {
+    id: "sftp-compressed-upload",
+    tab: "file-associations",
+    labelKey: "settings.sftp.compressedUpload.enable",
+    descriptionKey: "settings.sftp.compressedUpload.enableDesc",
+    sectionKey: "settings.sftp.compressedUpload",
+  },
   {
     id: "sftp-follow-terminal-cwd",
     tab: "file-associations",
@@ -691,6 +698,20 @@ export const SETTINGS_SEARCH_CATALOG: readonly SettingsSearchEntry[] = [
     labelKey: "settings.sftp.transferConcurrency",
     descriptionKey: "settings.sftp.transferConcurrency.desc",
   },
+  {
+    id: "sftp-skip-unchanged",
+    tab: "file-associations",
+    labelKey: "settings.sftp.skipUnchanged.enable",
+    descriptionKey: "settings.sftp.skipUnchanged.enableDesc",
+    sectionKey: "settings.sftp.transferConcurrency",
+  },
+  {
+    id: "sftp-transport-idle-ttl",
+    tab: "file-associations",
+    labelKey: "settings.ssh.transportIdleTtl",
+    descriptionKey: "settings.ssh.transportIdleTtl.desc",
+    sectionKey: "settings.sftp.transferConcurrency",
+  },
   {
     id: "sftp-default-opener",
     tab: "file-associations",

domain/sshPublicKey.shared.cjs

@@ -0,0 +1,84 @@
+"use strict";
+
+// Extract only the public-key wire blob for fingerprinting, never CA trust or
+// certificate validation. ssh2's getPublicSSH() preserves the full certificate,
+// and its internal base-type helper is not exported. Keep this byte-only helper
+// shared by Electron and the renderer so migration uses exactly the same bytes.
+// Layouts: OpenSSH PROTOCOL.certkeys (v00/v01) and PROTOCOL.u2f (SK).
+function extractCertificatePublicKey(blob) {
+  let offset = 0;
+  const view = new DataView(blob.buffer, blob.byteOffset, blob.byteLength);
+  const skip = (length) => {
+    if (offset + length > blob.length) throw new Error("Truncated SSH key");
+    offset += length;
+  };
+  const readString = () => {
+    skip(4);
+    const length = view.getUint32(offset - 4, false);
+    const start = offset;
+    skip(length);
+    return blob.subarray(start, offset);
+  };
+  const ascii = (bytes) => String.fromCharCode(...bytes);
+
+  try {
+    const typeBytes = readString();
+    if (typeBytes.length > 128) return null;
+    const match = ascii(typeBytes).match(/^(.*)-cert-v0([01])@openssh\.com$/);
+    if (!match) return null;
+    let baseType = match[1];
+    const v01 = match[2] === "1";
+    if (/^rsa-sha2-(256|512)$/.test(baseType)) baseType = "ssh-rsa";
+    if (baseType === "sk-ssh-ed25519" || baseType === "sk-ecdsa-sha2-nistp256") {
+      baseType += "@openssh.com";
+    }
+    let fields;
+    switch (baseType) {
+      case "ssh-rsa": fields = 2; break;
+      case "ssh-dss": fields = 4; break;
+      case "ssh-ed25519": fields = 1; break;
+      case "sk-ssh-ed25519@openssh.com": fields = 2; break;
+      case "sk-ecdsa-sha2-nistp256@openssh.com": fields = 3; break;
+      case "ecdsa-sha2-nistp256":
+      case "ecdsa-sha2-nistp384":
+      case "ecdsa-sha2-nistp521": fields = 2; break;
+      default: return null;
+    }
+
+    // v00 put its nonce after the constraints, not before the key material.
+    if (v01) readString();
+    const keyStart = offset;
+    for (let i = 0; i < fields; i += 1) {
+      const field = readString();
+      const isApplication = baseType.startsWith("sk-") && i === fields - 1;
+      if (!field.length && !isApplication) return null;
+      if (i === 0 && baseType.includes("ed25519") && field.length !== 32) return null;
+      if (i === 0 && baseType.includes("ecdsa")) {
+        const curve = baseType.replace(/^sk-/, "").replace(/@openssh\.com$/, "").replace(/^ecdsa-sha2-/, "");
+        if (field.length > 8 || ascii(field) !== curve) return null;
+      }
+    }
+    const keyEnd = offset;
+    // Check the outer envelope too; truncated/unsupported certificates retain
+    // their full-blob fingerprint rather than gaining an inner-key match.
+    if (v01) skip(8); // serial
+    skip(4); // host/user type
+    readString(); // key ID
+    readString(); // principals
+    skip(16); // validity
+    readString(); // critical options (v00 constraints)
+    readString(); // extensions (v00 nonce)
+    readString(); // reserved
+    if (!readString().length || !readString().length || offset !== blob.length) return null;
+
+    const result = new Uint8Array(4 + baseType.length + keyEnd - keyStart);
+    new DataView(result.buffer).setUint32(0, baseType.length, false);
+    for (let i = 0; i < baseType.length; i += 1) result[4 + i] = baseType.charCodeAt(i);
+    result.set(blob.subarray(keyStart, keyEnd), 4 + baseType.length);
+    return result;
+  } catch {
+    return null;
+  }
+}
+
+exports.extractCertificatePublicKey = extractCertificatePublicKey;

electron-builder.config.cjs

@@ -84,6 +84,7 @@ module.exports = {
         // is excluded below, so the shared TOTP runtime must be listed.
         'domain/totp.shared.cjs',
         'domain/totpPrompt.shared.cjs',
+        'domain/sshPublicKey.shared.cjs',
         'lib/**/*.cjs',
         'lib/**/*.json',
         'skills/**/*',

electron/bridges/ai/ptyExec.readiness.test.cjs

@@ -281,6 +281,26 @@ test('wall deadline during authorization reports authorization failure rather th
   assert.deepEqual(pty.writes, []);
 });
 
+test('idle Enter-PSSession remoting prompt allows the command to be sent', async () => {
+  const pty = new TestPty();
+  const session = { _promptTrackTail: '', lastIdlePrompt: '' };
+  const prompt = '[192.168.1.10]: PS C:\\Users\\Administrator\\Documents> ';
+  trackSessionIdlePrompt(session, `PowerShell 7\r\n${prompt}`);
+  assert.equal(readyPrompt(session), prompt);
+
+  const result = await startPtyJob(pty, 'Write-Output ok', {
+    shellKind: 'powershell',
+    getReadyPrompt: () => readyPrompt(session),
+    promptWaitTimeoutMs: 200,
+    timeoutMs: 1000,
+    typedInput: true,
+  }).resultPromise;
+  assert.equal(result.ok, true);
+  assert.equal(result.stdout, 'OK');
+  assert.equal(pty.writes.length, 1);
+  assert.match(pty.writes[0], /\$__NCMCP_/);
+});
+
 test('idle PowerShell whose raw tail was CSI-erased still receives the command', async (t) => {
   t.mock.timers.enable({ apis: ['Date', 'setTimeout'] });
   const pty = new TestPty();

electron/bridges/ai/shellUtils.cjs

@@ -50,11 +50,12 @@ function formatSyntheticEcho(command) {
 }
 
 // Default PowerShell prompt (e.g. `PS C:\Users\alice>`, `PS>`,
-// `PS /home/alice>`). Anchored so command output that merely starts with
-// `PS` (e.g. `PSO>`) doesn't match. The `\S` after `\s+` rejects literal
+// `PS /home/alice>`), with optional Enter-PSSession / remoting `[host]: `
+// and debug `[DBG]: ` prefixes. Anchored so command output that merely
+// starts with `PS` (e.g. `PSO>`) doesn't match. The `\S` after `\s+` rejects literal
 // `"PS >"` (which the default prompt never emits) so a script that prints
 // such a line can't trick prompt-driven shell-kind selection.
-const POWERSHELL_PROMPT_PATTERN = /^PS(?:\s+\S.*)?>$/;
+const POWERSHELL_PROMPT_PATTERN = /^(?:\[[^\]\r\n]+\]: )*PS(?:\s+\S.*)?>$/;
 
 // Default cmd.exe prompt (e.g. `C:\>`, `C:\Users\alice>`, `D:\data>`).
 // Drive letter + optional path + `>`. Rejects `C: >` (space before `>`) and
@@ -100,12 +101,6 @@ const OH_MY_ZSH_YS_HOST_LINE_PATTERN = /^#\s+[^\s@]+\s+@\s+[^\s]+(?:\s+[^\n\r]+)
 // within the path so partially entered commands do not count as idle prompts.
 const ALPINE_PROMPT_PATTERN = /^[A-Za-z0-9_][A-Za-z0-9_.-]*:(?:~(?:\/[^#$\n\r]*)?|\/[^#$\n\r]*)[#$]$/;
 
-// Default macOS bash PS1 `\h:\W \u\$` (also seen after `sudo -i`),
-// e.g. `ChrisdeMacBook-Air:~ root#`. Pure shape only; no shellKind gate.
-// Require a username after the path so Alpine `host:~#` / `host:/path#`
-// stay separate; the hostname excludes `@` so POSIX `user@host:...` stays separate.
-const MACOS_SUDO_ROOT_PROMPT_PATTERN = /^[A-Za-z0-9_][A-Za-z0-9_.-]*:(?:~|\/|[^\s:#$]+)\s+[A-Za-z0-9_.-]+[#$]$/;
-
 // Powerlevel10k / similar Unicode prompt-ending ❯ (U+276F). Common idle forms:
 // `~ ❯`, `~/path ❯`, `/tmp ❯`, short-dir `proj ❯`, optional `user@host `
 // prefix (`alice@host ~ ❯`). Require a non-empty prefix and whitespace before
@@ -144,7 +139,6 @@ function isDefaultPosixPromptLine(line) {
     POSIX_PROMPT_PATTERN.test(withoutEnvPrefix) ||
     PAREN_POSIX_PROMPT_PATTERN.test(withoutEnvPrefix) ||
     ALPINE_PROMPT_PATTERN.test(withoutEnvPrefix) ||
-    MACOS_SUDO_ROOT_PROMPT_PATTERN.test(withoutEnvPrefix) ||
     ZSH_PROMPT_PATTERN.test(withoutEnvPrefix) ||
     POWERLEVEL10K_PROMPT_PATTERN.test(withoutEnvPrefix) ||
     OH_MY_ZSH_ROBBYRUSSELL_PROMPT_PATTERN.test(withoutEnvPrefix)

electron/bridges/ai/shellUtils.test.cjs

@@ -112,6 +112,46 @@ test("isDefaultPowerShellPromptLine matches default shapes and rejects look-alik
   assert.equal(isDefaultPowerShellPromptLine(null), false);
 });
 
+test("PowerShell prompt helpers recognize remoting and debug prefixes", () => {
+  for (const prompt of [
+    "[192.168.1.10]: PS C:\\Users\\Administrator\\Documents>",
+    "[SERVER01]: PS C:\\>",
+    "[host.example.com]: PS C:\\Windows\\System32>",
+    "[fe80::1]: PS C:\\>",
+    "[DBG]: PS C:\\Users\\alice>",
+    "[SERVER01]: [DBG]: PS C:\\>",
+  ]) {
+    assert.equal(isDefaultPowerShellPromptLine(prompt), true, prompt);
+    assert.equal(extractTrailingIdlePrompt(`welcome\r\n${prompt}`), prompt, prompt);
+  }
+});
+
+test("PowerShell prompt helpers reject malformed remoting prefixes and look-alikes", () => {
+  for (const line of [
+    "[host] PS C:\\>",
+    "prefix [host]: PS C:\\>",
+    "[]: PS C:\\>",
+    "[ho]st]: PS C:\\>",
+    "[ho\rst]: PS C:\\>",
+    "[ho\nst]: PS C:\\>",
+    "[host]:PS C:\\>",
+    "[host]: PS >",
+    "PS >",
+    "PSO>",
+    "ZIPS>",
+    "",
+    null,
+  ]) {
+    assert.equal(isDefaultPowerShellPromptLine(line), false, String(line));
+    assert.equal(extractTrailingIdlePrompt(line), "", String(line));
+  }
+});
+
+test("extractTrailingIdlePrompt preserves trailing space on a remoting prompt", () => {
+  const prompt = "[192.168.1.10]: PS C:\\Users\\Administrator\\Documents> ";
+  assert.equal(extractTrailingIdlePrompt(`welcome\r\n${prompt}`), prompt);
+});
+
 test("extracts a trailing cmd.exe idle prompt", () => {
   // Windows OpenSSH default shell is cmd.exe; without capturing `C:\...>`
   // AI exec cannot select the cmd wrapper when shellKind is still unset.
@@ -298,57 +338,6 @@ test("extracts an Alpine idle prompt while preserving its trailing whitespace",
   assert.equal(extractTrailingIdlePrompt("localhost:~# \r\n"), "");
 });
 
-test("isDefaultPosixPromptLine matches macOS bash host:dir user prompts", () => {
-  for (const prompt of [
-    "ChrisdeMacBook-Air:~ root#",
-    "ChrisdeMacBook-Air:~ root# ",
-    "host:/tmp root#",
-    "host:tmp root#",
-    "host:/ root#",
-    "SomeHost:~ alice$",
-    "(venv) ChrisdeMacBook-Air:~ root# ",
-  ]) {
-    assert.equal(isDefaultPosixPromptLine(prompt), true, prompt);
-  }
-});
-
-test("macOS bash prompt recognition rejects authentication output and pending input", () => {
-  for (const line of [
-    "Password:",
-    "Sorry, try again.",
-    "ChrisdeMacBook-Air:~ root# ls",
-    "ChrisdeMacBook-Air:~ root# echo #",
-    "ChrisdeMacBook-Air:~root#",
-  ]) {
-    assert.equal(isDefaultPosixPromptLine(line), false, line);
-    assert.equal(extractTrailingIdlePrompt(`welcome\r\n${line}`), "", line);
-  }
-  for (const line of ["PS C:\\Users\\alice>", "C:\\Users\\alice>"]) {
-    assert.equal(isDefaultPosixPromptLine(line), false, line);
-  }
-});
-
-test("extracts a macOS bash idle prompt while preserving its trailing whitespace", () => {
-  assert.equal(
-    extractTrailingIdlePrompt("Welcome\r\n\x1b[32mChrisdeMacBook-Air:~ root# \x1b[0m"),
-    "ChrisdeMacBook-Air:~ root# ",
-  );
-  assert.equal(
-    extractTrailingIdlePrompt("(venv) ChrisdeMacBook-Air:~ root# "),
-    "(venv) ChrisdeMacBook-Air:~ root# ",
-  );
-});
-
-test("extracts the macOS root idle prompt after sudo -i finishes authentication", () => {
-  const transcript = "user@MacBook-Pro ~ % sudo -i\r\nPassword:";
-  assert.equal(extractTrailingIdlePrompt(transcript), "");
-  assert.equal(extractTrailingIdlePrompt(`${transcript}\r\nSorry, try again.`), "");
-  assert.equal(
-    extractTrailingIdlePrompt(`${transcript}\r\nChrisdeMacBook-Air:~ root# `),
-    "ChrisdeMacBook-Air:~ root# ",
-  );
-});
-
 test("isDefaultPosixPromptLine matches Powerlevel10k ❯ idle prompts", () => {
   for (const prompt of [
     "~ ❯",

electron/bridges/fixtures/hostCertificates.test.fixture.cjs

@@ -0,0 +1,76 @@
+const fs = require("node:fs");
+const path = require("node:path");
+const { execFileSync } = require("node:child_process");
+
+let sshKeygenSkip = false;
+try {
+  execFileSync("ssh-keygen", ["-h"], { stdio: "ignore" });
+} catch (error) {
+  if (error.code === "ENOENT") sshKeygenSkip = "ssh-keygen is not installed";
+}
+
+const sshString = (value) => {
+  const body = Buffer.from(value);
+  const length = Buffer.alloc(4);
+  length.writeUInt32BE(body.length);
+  return Buffer.concat([length, body]);
+};
+
+// Real local certificates, with no server/network or security-key device.
+function mintHostCertificates(t, { type = "ed25519", bits, sk = false, user = false } = {}) {
+  const dir = fs.mkdtempSync(path.join(__dirname, ".hostcert-"));
+  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  const keygen = (...args) => execFileSync("ssh-keygen", ["-q", ...args], { stdio: "pipe" });
+  const ca = path.join(dir, "ca");
+  keygen("-t", "ed25519", "-N", "", "-f", ca);
+  const readKey = (file) => {
+    const line = fs.readFileSync(file, "utf8").trim();
+    const [keyType, body] = line.split(/\s+/);
+    return { line, keyType, blob: Buffer.from(body, "base64") };
+  };
+  const mint = (name, validity, serial) => {
+    const host = path.join(dir, name);
+    if (!fs.existsSync(host)) {
+      keygen("-t", type, ...(bits ? ["-b", String(bits)] : []), "-N", "", "-f", host);
+      if (sk) {
+        const plain = readKey(`${host}.pub`);
+        const keyMaterial = plain.blob.subarray(4 + plain.keyType.length);
+        const skType = `sk-${plain.keyType}@openssh.com`;
+        const blob = Buffer.concat([sshString(skType), keyMaterial, sshString("ssh:netcatty-test")]);
+        fs.writeFileSync(`${host}.pub`, `${skType} ${blob.toString("base64")}\n`);
+      }
+    }
+    keygen("-s", ca, "-I", "netcatty-hostcert", ...(user ? [] : ["-h"]),
+      "-n", "127.0.0.1", "-V", validity, "-z", String(serial), `${host}.pub`);
+    const cert = readKey(`${host}-cert.pub`);
+    const listing = execFileSync("ssh-keygen", ["-L", "-f", `${host}-cert.pub`], { encoding: "utf8" });
+    const publicKeyFingerprint = listing.match(/Public key: .* SHA256:(\S+)/)?.[1];
+    if (!publicKeyFingerprint) throw new Error("Missing ssh-keygen certificate fingerprint");
+    return { ...cert, publicKeyFingerprint, plain: readKey(`${host}.pub`) };
+  };
+  return {
+    first: mint("host", "20250101:20260101", 1),
+    renewed: mint("host", "20260101:20270101", 2),
+    different: mint("other", "20260101:20270101", 3),
+  };
+}
+
+// Legacy v00 is no longer emitted by ssh-keygen. This follows the original
+// PROTOCOL.certkeys layout: key material first, nonce after constraints.
+function legacyCertificate(keyType, keyFields) {
+  const blob = Buffer.concat([
+    sshString(`${keyType}-cert-v00@openssh.com`),
+    ...keyFields.map(sshString),
+    Buffer.from([0, 0, 0, 2]),
+    sshString("legacy"), sshString(""), Buffer.alloc(16),
+    sshString(""), sshString("nonce"), sshString(""),
+    sshString("signing key"), sshString("signature"),
+  ]);
+  return {
+    blob,
+    plain: Buffer.concat([sshString(keyType), ...keyFields.map(sshString)]),
+    line: `${keyType}-cert-v00@openssh.com ${blob.toString("base64")}`,
+  };
+}
+
+module.exports = { mintHostCertificates, legacyCertificate, sshString, sshKeygenSkip };

electron/bridges/hostKeyVerifier.cjs

@@ -1,6 +1,7 @@
 const crypto = require("node:crypto");
 const { randomUUID } = require("node:crypto");
 const { utils: sshUtils } = require("ssh2");
+const { extractCertificatePublicKey } = require("../../domain/sshPublicKey.shared.cjs");
 
 const REQUEST_TTL_MS = 2 * 60 * 1000;
 const hostKeyRequests = new Map();
@@ -65,8 +66,9 @@ const fingerprintFromPublicKey = (publicKey) => {
   const parts = trimmed.split(/\s+/);
   if (parts.length >= 2 && /^ssh-|^ecdsa-|^sk-/.test(parts[0])) {
     try {
+      const blob = Buffer.from(parts[1], "base64");
       return crypto.createHash("sha256")
-        .update(Buffer.from(parts[1], "base64"))
+        .update(extractCertificatePublicKey(blob) || blob)
         .digest("base64")
         .replace(/=+$/g, "");
     } catch {
@@ -77,7 +79,16 @@ const fingerprintFromPublicKey = (publicKey) => {
 };
 
 const getKnownHostFingerprint = (knownHost) => {
-  return normalizeFingerprint(knownHost?.fingerprint)
+  const stored = normalizeFingerprint(knownHost?.fingerprint);
+  const parts = knownHost?.publicKey?.trim().split(/\s+/) || [];
+  if (parts.length >= 2 && /-cert-v0[01]@openssh\.com$/.test(parts[0])) {
+    const blob = Buffer.from(parts[1], "base64");
+    // Only replace an explicit fingerprint if it is the legacy full-cert hash.
+    // Fingerprint-only records cannot be migrated without the certificate body.
+    const legacy = crypto.createHash("sha256").update(blob).digest("base64").replace(/=+$/g, "");
+    if (!stored || stored === legacy) return fingerprintFromPublicKey(knownHost.publicKey);
+  }
+  return stored
     || fingerprintFromPublicKey(knownHost?.publicKey);
 };
 
@@ -134,7 +145,7 @@ const classifyHostKey = ({ knownHosts = [], hostname, port = 22, keyType, finger
 const describeHostKey = (rawKey) => {
   const key = Buffer.isBuffer(rawKey) ? rawKey : Buffer.from(rawKey || "");
   const fingerprint = crypto.createHash("sha256")
-    .update(key)
+    .update(extractCertificatePublicKey(key) || key)
     .digest("base64")
     .replace(/=+$/g, "");
   let keyType = "unknown";
@@ -149,7 +160,9 @@ const describeHostKey = (rawKey) => {
   try {
     const parsed = sshUtils.parseKey(key);
     const parsedKey = Array.isArray(parsed) ? parsed[0] : parsed;
-    if (parsedKey && !(parsedKey instanceof Error)) {
+    // Keep the presented certificate identity, even if a parser returns its
+    // base algorithm or underlying public key as metadata.
+    if (parsedKey && !(parsedKey instanceof Error) && !/-cert-v0[01]@openssh\.com$/.test(keyType)) {
       keyType = parsedKey.type || keyType;
       const publicSsh = parsedKey.getPublicSSH?.();
       if (publicSsh) publicKey = publicSsh.toString("utf8");

electron/bridges/hostKeyVerifier.test.cjs

@@ -1,11 +1,13 @@
 const test = require("node:test");
 const assert = require("node:assert/strict");
 const crypto = require("node:crypto");
+const { mintHostCertificates, legacyCertificate, sshString, sshKeygenSkip } = require("./fixtures/hostCertificates.test.fixture.cjs");
 
 const {
   classifyHostKey,
   createHostVerifier,
   describeHostKey,
+  getKnownHostFingerprint,
   handleResponse,
   normalizeFingerprint,
 } = require("./hostKeyVerifier.cjs");
@@ -17,6 +19,84 @@ const makeRawPublicKey = (keyType, body = "trusted imported host key") => {
   return Buffer.concat([length, type, Buffer.from(body)]);
 };
 
+const hashKey = (blob) => crypto.createHash("sha256").update(blob).digest("base64").replace(/=+$/g, "");
+
+test("host certificate renewals trust the inner key, including legacy saved fingerprints", { skip: sshKeygenSkip }, (t) => {
+  const { first, renewed, different } = mintHostCertificates(t);
+  const original = describeHostKey(first.blob);
+  const live = describeHostKey(renewed.blob);
+  const changed = describeHostKey(different.blob);
+  assert.notDeepEqual(first.blob, renewed.blob);
+  assert.equal(original.fingerprint, first.publicKeyFingerprint);
+  assert.equal(live.fingerprint, original.fingerprint);
+  assert.notEqual(changed.fingerprint, live.fingerprint);
+  assert.equal(original.keyType, "ssh-ed25519-cert-v01@openssh.com");
+  assert.equal(original.publicKey, `${first.keyType} ${first.blob.toString("base64")}`);
+  assert.equal(describeHostKey(first.plain.blob).fingerprint, hashKey(first.plain.blob));
+
+  const stored = { id: "kh-cert", hostname: "cert.local", port: 2222, ...original };
+  const classify = (key, record = stored) => classifyHostKey({
+    knownHosts: [record], hostname: "cert.local", port: 2222, ...key,
+  });
+  assert.equal(classify(live).status, "trusted");
+  assert.equal(classify(changed).status, "changed");
+  assert.equal(classify(changed, { ...stored, keyType: "ssh-rsa" }).status, "unknown");
+
+  const legacy = { ...stored, fingerprint: hashKey(first.blob) };
+  assert.notEqual(legacy.fingerprint, live.fingerprint);
+  assert.equal(getKnownHostFingerprint(legacy), live.fingerprint);
+  assert.equal(classify(live, legacy).status, "trusted");
+  assert.equal(classify(changed, legacy).status, "changed");
+  assert.equal(classify(live, { ...legacy, publicKey: undefined }).status, "changed");
+  assert.equal(classify(live, { ...legacy, publicKey: `SHA256:${legacy.fingerprint}` }).status, "changed");
+  assert.equal(classify(live, { ...legacy, fingerprint: "unrelated-explicit-fingerprint" }).status, "changed");
+  assert.equal(classify(live, { ...legacy, fingerprint: undefined }).status, "trusted");
+
+  // Renewal is trusted on reconnect, but changing the raw certificate during
+  // an established connection must still be rejected synchronously on rekey.
+  const verifier = createHostVerifier({ hostname: stored.hostname, port: stored.port, knownHosts: [legacy] });
+  const results = [];
+  verifier(first.blob, (accepted) => results.push(accepted));
+  verifier(Buffer.from(first.blob), (accepted) => results.push(accepted));
+  verifier(renewed.blob, (accepted) => results.push(accepted));
+  assert.deepEqual(results, [true, true, false]);
+});
+
+for (const options of [
+  { type: "rsa", bits: 2048 },
+  ...[256, 384, 521].map((bits) => ({ type: "ecdsa", bits })),
+  { type: "ed25519", sk: true },
+  { type: "ecdsa", bits: 256, sk: true },
+  { type: "ed25519", user: true },
+]) {
+  test(`certificate fingerprint matches ssh-keygen for ${JSON.stringify(options)}`, { skip: sshKeygenSkip }, (t) => {
+    const { first, renewed, different } = mintHostCertificates(t, options);
+    assert.equal(describeHostKey(first.blob).fingerprint, first.publicKeyFingerprint);
+    assert.equal(describeHostKey(first.blob).fingerprint, hashKey(first.plain.blob));
+    assert.equal(describeHostKey(renewed.blob).fingerprint, first.publicKeyFingerprint);
+    assert.notEqual(describeHostKey(different.blob).fingerprint, first.publicKeyFingerprint);
+  });
+}
+
+test("v00 certificates extract the key before the nonce", () => {
+  for (const [type, fields] of [["ssh-rsa", ["exponent", "modulus"]], ["ssh-dss", ["p", "q", "g", "y"]]]) {
+    const cert = legacyCertificate(type, fields);
+    assert.equal(describeHostKey(cert.blob).fingerprint, hashKey(cert.plain));
+    assert.equal(describeHostKey(cert.blob).keyType, `${type}-cert-v00@openssh.com`);
+  }
+});
+
+test("malformed and unsupported certificates keep their full-blob fingerprint", () => {
+  const truncated = Buffer.concat([
+    sshString("ssh-ed25519-cert-v01@openssh.com"), sshString("nonce"), sshString(Buffer.alloc(32)),
+  ]);
+  const badLength = Buffer.concat([sshString("ssh-ed25519-cert-v01@openssh.com"), Buffer.from([255, 255, 255, 255])]);
+  const unsupported = Buffer.concat([sshString("unknown-cert-v01@openssh.com"), sshString("nonce")]);
+  for (const blob of [truncated, badLength, unsupported]) {
+    assert.equal(describeHostKey(blob).fingerprint, hashKey(blob));
+  }
+});
+
 test("classifyHostKey prompts for unknown hosts", () => {
   const result = classifyHostKey({
     knownHosts: [],

electron/bridges/sftpBridge.cjs

@@ -1913,6 +1913,16 @@ function createSessionBackedSftpClient(sessionId, sshClient, options = {}) {
       const attrs = await statAsync(sftp, remotePath);
       return statResultFromAttrs(attrs);
     },
+    async lstat(remotePath) {
+      const sftp = await requireSftpChannel(client);
+      // Copy preflights must inspect link nodes, never their followed targets.
+      // lstatAsync falls back to STAT when LSTAT is absent, so reject first.
+      if (typeof sftp.lstat !== "function") {
+        throw Object.assign(new Error("Remote server does not support LSTAT"), { code: "ENOTSUP" });
+      }
+      const attrs = await lstatAsync(sftp, remotePath);
+      return statResultFromAttrs(attrs);
+    },
     async realPath(remotePath) {
       const sftp = await requireSftpChannel(client);
       return await realpathAsync(sftp, remotePath);

electron/bridges/sftpBridge.sessionBackedCopy.test.cjs

@@ -0,0 +1,94 @@
+const test = require("node:test");
+const assert = require("node:assert/strict");
+const { EventEmitter } = require("node:events");
+const { Readable, PassThrough } = require("node:stream");
+const sftpBridge = require("./sftpBridge.cjs");
+const transferBridge = require("./transferBridge.cjs");
+
+const missing = () => Object.assign(new Error("ENOENT"), { code: 2 });
+
+async function openSessionClient(t, { sourceIsLink = false, targetExists = false } = {}) {
+  const commands = [];
+  const channel = new EventEmitter();
+  channel.readdir = (_path, callback) => callback(null, []);
+  channel.mkdir = (_path, callback) => callback(null);
+  channel.unlink = (_path, callback) => callback(null);
+  channel.stat = (remotePath, callback) => {
+    if (String(remotePath) === "/target/file" && !targetExists) return callback(missing());
+    callback(null, { size: 66, mode: 0o100640, mtime: 1 });
+  };
+  channel.lstat = (remotePath, callback) => {
+    if (String(remotePath) === "/target" && !targetExists) return callback(missing());
+    callback(null, { size: 66, mode: sourceIsLink ? 0o120777 : 0o100640, mtime: 1 });
+  };
+  channel.createReadStream = () => Readable.from([Buffer.alloc(66)]);
+  const connection = {
+    sftp(callback) { callback(null, channel); },
+    exec(command, callback) {
+      commands.push(command);
+      const stream = new PassThrough();
+      stream.stderr = new PassThrough();
+      callback(null, stream);
+      setImmediate(() => stream.emit("close", 0));
+    },
+  };
+  const clients = new Map();
+  sftpBridge.init({
+    electronModule: { webContents: { fromId: () => null } },
+    sessions: new Map([["copy-session", { conn: connection }]]),
+    sftpClients: clients,
+  });
+  transferBridge.init({ sftpClients: clients });
+  const { sftpId } = await sftpBridge.openSftpForSession(null, {
+    sessionId: "copy-session", fileProtocol: "sftp",
+  });
+  t.after(() => sftpBridge.closeSftp(null, { sftpId }));
+  return { client: clients.get(sftpId), channel, commands, sftpId };
+}
+
+test("same-host file copy executes cp using the actual session-backed client (#4207)", async (t) => {
+  const { commands, sftpId } = await openSessionClient(t);
+  const result = await transferBridge.startTransfer({ sender: { send() {} } }, {
+    transferId: "session-backed-file-copy",
+    sourcePath: "/source/file", targetPath: "/target/file",
+    sourceType: "sftp", targetType: "sftp",
+    sourceSftpId: sftpId, targetSftpId: sftpId,
+    sourceEncoding: "utf-8", targetEncoding: "utf-8",
+    totalBytes: 66, sameHost: true, resumable: false,
+  });
+  assert.deepEqual(commands, ["cp -a '/source/file' '/target/file'"]);
+  assert.equal(result.error, undefined);
+});
+
+for (const sourceIsLink of [false, true]) {
+  test(`session-backed LSTAT preserves link classification (${sourceIsLink})`, async (t) => {
+    const { client } = await openSessionClient(t, { sourceIsLink });
+    assert.equal((await client.lstat("/source/file")).isSymbolicLink, sourceIsLink);
+    assert.equal((await client.stat("/source/file")).isSymbolicLink, false);
+  });
+}
+
+for (const unsupported of ["missing-method", "server-error"]) {
+  test(`session-backed LSTAT never follows STAT on ${unsupported}`, async (t) => {
+    const { client, channel } = await openSessionClient(t);
+    let statCalls = 0;
+    channel.stat = () => { statCalls++; throw new Error("must not follow symlinks"); };
+    if (unsupported === "missing-method") delete channel.lstat;
+    else channel.lstat = (_path, callback) => callback(Object.assign(new Error("unsupported"), { code: 8 }));
+    await assert.rejects(() => client.lstat("/source/file"), error =>
+      error.code === (unsupported === "missing-method" ? "ENOTSUP" : 8));
+    assert.equal(statCalls, 0);
+  });
+}
+
+for (const targetExists of [false, true]) {
+  test(`session-backed directory cp preserves the destination merge guard (${targetExists})`, async (t) => {
+    const { commands, sftpId } = await openSessionClient(t, { targetExists });
+    const result = await transferBridge.sameHostCopyDirectory({ sender: { send() {} } }, {
+      transferId: `session-backed-directory-copy-${targetExists}`,
+      sftpId, sourcePath: "/source", targetPath: "/target", encoding: "utf-8",
+    });
+    assert.equal(result.success, !targetExists);
+    assert.deepEqual(commands, targetExists ? [] : ["cp -ra '/source/.' '/target/'"]);
+  });
+}

electron/bridges/sshBridge/systemKnownHosts.cjs

@@ -41,6 +41,8 @@
  * leaves the Mosh stats bar empty (graceful degradation), never weakens
  * security.
  */
+const { extractCertificatePublicKey } = require("../../../domain/sshPublicKey.shared.cjs");
+
 function createSystemKnownHostsApi(ctx) {
   const { fs, path, os, crypto, log } = ctx;
 
@@ -64,7 +66,7 @@ function createSystemKnownHostsApi(ctx) {
     }
     if (blob.length === 0) return "";
     return stripFingerprintPadding(
-      crypto.createHash("sha256").update(blob).digest("base64"),
+      crypto.createHash("sha256").update(extractCertificatePublicKey(blob) || blob).digest("base64"),
     );
   };
 
@@ -176,7 +178,7 @@ function createSystemKnownHostsApi(ctx) {
 
   // Parse one known_hosts line into { revoked, certAuthority, hostField,
   // keyType, fingerprint } or null when it is a comment / blank / malformed.
-  // The fingerprint is the SHA-256 of the line's key blob.
+  // Certificates pin their underlying key, just like the live verifier.
   const parseKnownHostsLine = (rawLine) => {
     const line = String(rawLine || "").trim();
     if (!line || line.startsWith("#")) return null;

electron/bridges/sshBridge/systemKnownHosts.test.cjs

@@ -1,6 +1,8 @@
 const test = require("node:test");
 const assert = require("node:assert/strict");
 const crypto = require("node:crypto");
+const { mintHostCertificates, sshKeygenSkip } = require("../fixtures/hostCertificates.test.fixture.cjs");
+const { describeHostKey } = require("../hostKeyVerifier.cjs");
 const path = require("node:path");
 const os = require("node:os");
 
@@ -59,6 +61,22 @@ function hashedHostField(token, salt = crypto.randomBytes(20)) {
 
 const HOME_KH = path.join(os.homedir(), ".ssh", "known_hosts");
 
+test("system certificate entries pin the inner key across renewals without CA trust", { skip: sshKeygenSkip }, (t) => {
+  const { first, renewed, different } = mintHostCertificates(t);
+  const { api } = makeApi({ [HOME_KH]: `example.com ${first.line}\n` });
+  const liveFingerprint = describeHostKey(renewed.blob).fingerprint;
+  assert.equal(api.parseKnownHostsLine(`example.com ${first.line}`).fingerprint, liveFingerprint);
+  assert.equal(api.isHostKeyTrustedBySystem({ hostname: "example.com", fingerprint: liveFingerprint }), true);
+  assert.equal(api.isHostKeyTrustedBySystem({
+    hostname: "example.com", fingerprint: describeHostKey(different.blob).fingerprint,
+  }), false);
+
+  const revoked = makeApi({ [HOME_KH]: `example.com ${first.line}\n@revoked example.com ${renewed.line}\n` });
+  assert.equal(revoked.api.isHostKeyTrustedBySystem({ hostname: "example.com", fingerprint: liveFingerprint }), false);
+  const ca = makeApi({ [HOME_KH]: `@cert-authority example.com ${first.line}\n` });
+  assert.equal(ca.api.isHostKeyTrustedBySystem({ hostname: "example.com", fingerprint: liveFingerprint }), false);
+});
+
 test("system known_hosts paths include the OpenSSH defaults for the platform", () => {
   const { api } = makeApi();
   const paths = api.getSystemKnownHostsPaths();

electron/bridges/transferBridge.cjs

@@ -7174,6 +7174,13 @@ async function startTransferNow(event, payload, onProgress) {
         const singleChannelCopy = srcClient.__netcattySingleChannelSsh || sshClient?.__netcattySingleChannelSsh;
         if (sshClient && typeof sshClient.exec === 'function' && !singleChannelCopy) {
           try {
+            // cp -a preserves link nodes; the SFTP fallback follows target bytes.
+            // A failed lstat also falls through to that existing route.
+            const sourceAttrs = await runCancelablePreflight(() => srcClient.lstat(
+              encodePathForSession(sourceSftpId, sourcePath, resolvedSourceEnc),
+            ));
+            if (sourceAttrs.isSymbolicLink) throw new Error("Source is a symbolic link");
+
             const dir = path.dirname(targetPath).replace(/\\/g, '/');
             try {
               await runTransferAbortableOperation(transfer, (signal) => ensureRemoteDirForSession(
@@ -7186,6 +7193,18 @@ async function startTransferNow(event, payload, onProgress) {
               if (transfer.cancelled || transfer.signal?.aborted) throw new Error("Transfer cancelled");
             }
 
+            const targetClient = sftpClients.get(targetSftpId);
+            let existingRemoteMode = null;
+            try {
+              const attrs = await runCancelablePreflight(() => targetClient.stat(
+                encodePathForSession(targetSftpId, targetPath, resolvedTargetEnc),
+              ));
+              if (Number.isFinite(attrs?.mode)) existingRemoteMode = attrs.mode & 0o7777;
+            } catch {
+              // Missing destinations or failed stats need no permission restore.
+              if (transfer.cancelled || transfer.signal?.aborted) throw new Error("Transfer cancelled");
+            }
+
             const escapedSource = sourcePath.replace(/'/g, "'\\''");
             const escapedTarget = targetPath.replace(/'/g, "'\\''");
             const command = `cp -a '${escapedSource}' '${escapedTarget}'`;
@@ -7194,6 +7213,13 @@ async function startTransferNow(event, payload, onProgress) {
             if (result.code === 0) {
               sendProgress(fileSize, fileSize);
               sameHostDone = true;
+              await restoreRemoteUploadModeBestEffort(
+                targetClient,
+                targetSftpId,
+                targetPath,
+                resolvedTargetEnc,
+                existingRemoteMode,
+              );
             } else if (result.code === 127) {
               // Exit 127 = command not found — cache to skip future attempts
               cpUnavailableSet.add(srcClient);
@@ -8204,11 +8230,28 @@ async function sameHostCopyDirectory(event, payload) {
     }
     if (cpUnavailableSet.has(client)) return { success: false };
 
+    const resolvedEncoding = resolveEncodingForRequest(sftpId, encoding);
+    if (resolvedEncoding && resolvedEncoding !== 'utf-8') {
+      return { success: false };
+    }
+
     const sshClient = client.client;
     if (!sshClient || typeof sshClient.exec !== 'function') {
       return { success: false };
     }
 
+    // Merges must use recursive SFTP transfers to preserve destination child modes.
+    // Only a clearly missing target is safe for the remote cp optimization.
+    try {
+      await runTransferCancelablePreflight(transfer, () => client.lstat(
+        encodePathForSession(sftpId, targetPath, resolvedEncoding),
+      ));
+      return { success: false };
+    } catch (error) {
+      if (transfer.cancelled) throw new Error("Transfer cancelled");
+      if (!isMissingRemoteStageError(error)) return { success: false };
+    }
+
     if (transfer.cancelled) throw new Error("Transfer cancelled");
     const lifecyclePayload = {
       ...payload,
@@ -8233,8 +8276,7 @@ async function sameHostCopyDirectory(event, payload) {
       if (transfer.cancelled) throw new Error("Transfer cancelled");
     }
 
-    // Use "source/." to copy directory *contents* into target, preserving merge
-    // semantics consistent with the recursive per-file transfer path.
+    // Use "source/." to copy directory *contents* into the newly created target.
     // Without "/.", `cp -ra source target` would create target/source/ when target exists.
     const escapedSource = sourcePath.replace(/'/g, "'\\''");
     const escapedTarget = targetPath.replace(/'/g, "'\\''");

electron/bridges/transferBridge.globalFanout.test.cjs

@@ -106,6 +106,7 @@ test("same-host cp capability cache follows the live SFTP client, not a recycled
   bridge.init({ sftpClients });
 
   const makeClient = (exitCode, calls) => ({
+    async lstat() { throw Object.assign(new Error("ENOENT"), { code: 2 }); },
     client: {
       exec(_command, callback) {
         calls.count += 1;

electron/bridges/transferBridge.test.cjs

@@ -1294,7 +1294,9 @@ test("server-to-server resume cancellation settles while source identity verific
   t.after(async () => fs.promises.rm(tempPath, { force: true }));
   let markPrefixStarted;
   const prefixStarted = new Promise((resolve) => { markPrefixStarted = resolve; });
+  let execCalls = 0;
   const sourceClient = {
+    client: { exec() { execCalls += 1; throw new Error("checkpointed copies must not exec cp"); } },
     sftp: createFastSftp({
       createReadStream() {
         markPrefixStarted();
@@ -1317,7 +1319,7 @@ test("server-to-server resume cancellation settles while source identity verific
     targetSftpId: "target",
     totalBytes: 8,
     resumable: true,
-    sameHost: false,
+    sameHost: true,
     resumeStage: "download",
     checkpointBytes: 4,
     downloadCheckpointBytes: 4,
@@ -1332,6 +1334,7 @@ test("server-to-server resume cancellation settles while source identity verific
   ]);
 
   assert.match(result.error || "", /cancel/i);
+  assert.equal(execCalls, 0, "same-host resume must verify its saved prefix instead of running cp");
   assert.equal(sender.sent.some((entry) => entry.channel === "netcatty:transfer:cancelled"), true);
   assert.equal(sender.sent.some((entry) => entry.channel === "netcatty:transfer:complete"), false);
 });
@@ -13243,6 +13246,119 @@ test("same-host directory copy rejected by a committed close leaves no lease or
   assert.equal(sftpTransferSessionLeaseStore.getLeaseCount(sftpId), 0);
 });
 
+test("same-host directory copy skips cp when auto encoding resolves to non-UTF-8", async (t) => {
+  const {
+    sftpTransferSessionLeaseStore,
+  } = require("./sftpTransferSessionLease.cjs");
+  sftpTransferSessionLeaseStore.resetForTests();
+  t.after(() => sftpTransferSessionLeaseStore.resetForTests());
+
+  const sftpId = "same-host-directory-auto-gb18030";
+  // Seed the session's resolved encoding before the copy requests auto.
+  sftpBridge.resolveEncodingForRequest(sftpId, "gb18030");
+  let execCalls = 0;
+  transferBridge.init({
+    sftpClients: new Map([[sftpId, {
+      client: {
+        exec(_command, callback) {
+          execCalls += 1;
+          const stream = new EventEmitter();
+          stream.stderr = new EventEmitter();
+          callback(null, stream);
+          setImmediate(() => stream.emit("close", 0));
+        },
+      },
+    }]]),
+  });
+  const sender = createSender();
+
+  const result = await transferBridge.sameHostCopyDirectory(
+    { sender },
+    {
+      transferId: "same-host-directory-auto-gb18030-copy",
+      sftpId,
+      sourcePath: "/source",
+      targetPath: "/\u76ee\u6807",
+      encoding: "auto",
+    },
+  );
+
+  assert.equal(execCalls, 0);
+  assert.equal(result.success, false);
+  assert.deepEqual(sender.sent, []);
+  assert.equal(transferBridge._getActiveTransferCountForTests(), 0);
+  assert.equal(sftpTransferSessionLeaseStore.getLeaseCount(sftpId), 0);
+});
+
+for (const targetState of ["existing", "missing", "stat-error"]) {
+  test(`same-host directory copy ${targetState} target uses cp only for a fresh destination`, async (t) => {
+    const { sftpTransferSessionLeaseStore } = require("./sftpTransferSessionLease.cjs");
+    sftpTransferSessionLeaseStore.resetForTests();
+    t.after(() => sftpTransferSessionLeaseStore.resetForTests());
+    const sftpId = `same-host-directory-${targetState}`;
+    const commands = [];
+    const mkdirs = [];
+    let targetExists = targetState === "existing";
+    const client = {
+      async lstat(remotePath) {
+        assert.equal(String(remotePath), "/target");
+        assert.deepEqual(mkdirs, [], "check the destination before ensuring it");
+        if (targetState === "stat-error") {
+          throw Object.assign(new Error("Permission denied"), { code: 3 });
+        }
+        if (!targetExists) throw Object.assign(new Error("ENOENT"), { code: 2 });
+        return { isDirectory: true };
+      },
+      sftp: createFastSftp({
+        stat(_remotePath, callback) {
+          if (!targetExists) {
+            callback(Object.assign(new Error("ENOENT"), { code: 2 }));
+            return;
+          }
+          callback(null, { isDirectory: () => true });
+        },
+        mkdir(remotePath, callback) {
+          mkdirs.push(String(remotePath));
+          targetExists = true;
+          callback(null);
+        },
+      }),
+      client: {
+        exec(command, callback) {
+          commands.push(command);
+          assert.equal(targetExists, true, "create the fresh destination before cp");
+          const stream = new PassThrough();
+          stream.stderr = new PassThrough();
+          callback(null, stream);
+          setImmediate(() => stream.emit("close", 0));
+        },
+      },
+    };
+    const sftpClients = new Map([[sftpId, client]]);
+    transferBridge.init({ sftpClients });
+    sftpBridge.init({ sftpClients });
+    const sender = createSender();
+    const result = await transferBridge.sameHostCopyDirectory({ sender }, {
+      transferId: `${sftpId}-copy`, sftpId,
+      sourcePath: "/source", targetPath: "/target", encoding: "utf-8",
+    });
+
+    if (targetState === "missing") {
+      assert.deepEqual(result, { success: true });
+      assert.deepEqual(commands, ["cp -ra '/source/.' '/target/'"]);
+      assert.deepEqual(mkdirs, ["/target"]);
+      assert.equal(sender.sent.some(entry => entry.channel === "netcatty:transfer:complete"), true);
+    } else {
+      assert.deepEqual(result, { success: false });
+      assert.deepEqual(commands, []);
+      assert.deepEqual(mkdirs, []);
+      assert.deepEqual(sender.sent, []);
+    }
+    assert.equal(transferBridge._getActiveTransferCountForTests(), 0);
+    assert.equal(sftpTransferSessionLeaseStore.getLeaseCount(sftpId), 0);
+  });
+}
+
 test("same-host directory copy cancellation aborts cp and releases its lease", async (t) => {
   const {
     sftpTransferSessionLeaseStore,
@@ -13259,6 +13375,7 @@ test("same-host directory copy cancellation aborts cp and releases its lease", a
   stream.end = () => {};
   stream.destroy = () => {};
   const client = {
+    async lstat() { throw Object.assign(new Error("ENOENT"), { code: 2 }); },
     client: {
       exec(_command, callback) {
         callback(null, stream);
@@ -13342,6 +13459,7 @@ test("same-host file cp cancellation releases the shared session lease", async (
   stream.end = () => {};
   stream.destroy = () => {};
   const client = {
+    lstat: async () => ({ isSymbolicLink: false }),
     client: {
       exec(_command, callback) {
         callback(null, stream);
@@ -15139,3 +15257,209 @@ test("pending channel-open skips the fastPut reopen and uses the shared channel"
   assert.ok(sharedWrites >= 1);
   assert.deepEqual(remoteFiles.get(targetPath), payload);
 });
+
+test("same-host file cp restores existing destination mode", async () => {
+  const commands = [];
+  const chmods = [];
+  let targetMode = 0o100600;
+  let downloads = 0;
+  let uploads = 0;
+  const sourceSftp = createFastSftp({
+    open() { downloads++; throw new Error("unexpected download"); },
+  });
+  const sourceClient = {
+    sftp: sourceSftp,
+    lstat: async () => ({ isSymbolicLink: false }),
+    stat: async () => ({ size: 64, mode: 0o100644 }),
+    client: {
+      sftp: (callback) => callback(null, sourceSftp),
+      exec(command, callback) {
+        commands.push(command);
+        targetMode = 0o100644;
+        const stream = new PassThrough();
+        stream.stderr = new PassThrough();
+        callback(null, stream);
+        setImmediate(() => stream.emit("close", 0));
+      },
+    },
+  };
+  const targetClient = {
+    sftp: createFastSftp({
+      open() { uploads++; throw new Error("unexpected upload"); },
+    }),
+    stat: async () => ({ size: 64, mode: targetMode }),
+    chmod: async (remotePath, mode) => {
+      chmods.push([String(remotePath), mode]);
+      targetMode = mode;
+    },
+  };
+  transferBridge.init({ sftpClients: new Map([["source", sourceClient], ["target", targetClient]]) });
+  const result = await transferBridge.startTransfer({ sender: createSender() }, {
+    transferId: `same-host-cp-mode-${crypto.randomUUID()}`,
+    sourcePath: "/source/payload.bin", targetPath: "/target/payload.bin",
+    sourceType: "sftp", targetType: "sftp",
+    sourceSftpId: "source", targetSftpId: "target",
+    sourceEncoding: "utf-8", targetEncoding: "utf-8",
+    totalBytes: 64,
+    sameHost: true, resumable: false,
+  });
+  assert.equal(result.error, undefined, result.error);
+  assert.deepEqual(commands, ["cp -a '/source/payload.bin' '/target/payload.bin'"]);
+  assert.deepEqual(chmods, [["/target/payload.bin", 0o600]]);
+  assert.equal(targetMode, 0o600);
+  assert.equal(downloads, 0);
+  assert.equal(uploads, 0);
+});
+
+for (const sourceState of ["symlink", "lstat-error"]) {
+  test(`same-host file cp skips a source ${sourceState} and downloads/uploads target bytes`, async (t) => {
+    const transferId = `same-host-cp-fallback-${crypto.randomUUID()}`;
+    const sourcePath = "/opt/app/config";
+    const targetPath = "/tmp/app/config";
+    const payload = Buffer.from("contents of ../shared/config");
+    const commands = [];
+    let reads = 0;
+    let remote = Buffer.alloc(0);
+    let promoted = false;
+    const { sftp: sourceSftp } = createPipelinedDownloadSftp(payload);
+    const originalRead = sourceSftp.read;
+    sourceSftp.read = (...args) => { reads++; originalRead(...args); };
+    const sourceClient = {
+      sftp: sourceSftp,
+      async lstat(remotePath) {
+        assert.equal(String(remotePath), sourcePath);
+        if (sourceState === "lstat-error") throw new Error("lstat unsupported");
+        return { isSymbolicLink: true, size: "../shared/config".length };
+      },
+      stat: async () => ({ size: payload.length }),
+      client: {
+        sftp: (callback) => callback(null, sourceSftp),
+        exec(command, callback) {
+          commands.push(command);
+          callback(new Error("unexpected exec"));
+        },
+      },
+    };
+    const targetSftp = createFastSftp({
+      open(_path, _flags, callback) { callback(null, Buffer.from("target-handle")); },
+      write(_handle, buffer, offset, length, position, callback) {
+        if (remote.length < position + length) {
+          remote = Buffer.concat([remote, Buffer.alloc(position + length - remote.length)]);
+        }
+        buffer.copy(remote, position, offset, offset + length);
+        callback(null);
+      },
+      close(_handle, callback) { callback(null); },
+    });
+    const targetClient = {
+      sftp: targetSftp,
+      client: { sftp: (callback) => callback(null, targetSftp) },
+      async stat(remotePath) {
+        if (String(remotePath) === targetPath && remote.length === 0) {
+          throw Object.assign(new Error("ENOENT"), { code: 2 });
+        }
+        return { size: remote.length };
+      },
+      rename: async () => { promoted = true; },
+      delete: async () => {},
+    };
+    transferBridge.init({ sftpClients: new Map([["source", sourceClient], ["target", targetClient]]) });
+    const localStage = tempDirBridge.getTransferTempFilePath(transferId, "config");
+    t.after(async () => fs.promises.rm(localStage, { force: true }));
+    const result = await transferBridge.startTransfer({ sender: createSender() }, {
+      transferId, sourcePath, targetPath,
+      sourceType: "sftp", targetType: "sftp",
+      sourceSftpId: "source", targetSftpId: "target",
+      sourceEncoding: "utf-8", targetEncoding: "utf-8",
+      totalBytes: payload.length, sameHost: true, resumable: false,
+    });
+
+    assert.equal(result.error, undefined, result.error);
+    assert.deepEqual(commands, [], "source symlinks and lstat failures must bypass cp -a");
+    assert.ok(reads > 0, "fallback must download the followed source contents");
+    assert.deepEqual(remote, payload, "fallback must upload target bytes rather than the link node");
+    assert.equal(promoted, true);
+  });
+}
+
+for (const cpResult of [0, 127, 1, "exec-error"]) {
+  test(`fresh same-host file cp result ${cpResult} preserves copy/fallback behavior (#4207)`, async (t) => {
+    const transferId = `same-host-cp-${crypto.randomUUID()}`;
+    const payload = Buffer.from("same-host ordinary SFTP copy");
+    const commands = [];
+    const chmods = [];
+    let reads = 0;
+    let remote = Buffer.alloc(0);
+    let promoted = false;
+    const { sftp: sourceSftp } = createPipelinedDownloadSftp(payload);
+    const originalRead = sourceSftp.read;
+    sourceSftp.read = (...args) => { reads++; originalRead(...args); };
+    const sourceClient = {
+      sftp: sourceSftp,
+      lstat: async () => ({ isSymbolicLink: false }),
+      stat: async () => ({ size: payload.length }),
+      client: {
+        sftp: (callback) => callback(null, sourceSftp),
+        exec(command, callback) {
+          commands.push(command);
+          if (cpResult === "exec-error") { callback(new Error("exec denied")); return; }
+          const stream = new PassThrough();
+          stream.stderr = new PassThrough();
+          callback(null, stream);
+          setImmediate(() => stream.emit("close", cpResult));
+        },
+      },
+    };
+    const targetSftp = createFastSftp({
+      open(_path, _flags, callback) { callback(null, Buffer.from("target-handle")); },
+      write(_handle, buffer, offset, length, position, callback) {
+        if (remote.length < position + length) {
+          remote = Buffer.concat([remote, Buffer.alloc(position + length - remote.length)]);
+        }
+        buffer.copy(remote, position, offset, offset + length);
+        callback(null);
+      },
+      close(_handle, callback) { callback(null); },
+    });
+    const targetClient = {
+      sftp: targetSftp,
+      client: { sftp: (callback) => callback(null, targetSftp) },
+      stat: async (remotePath) => {
+        if (String(remotePath) === "/target/payload.bin" && remote.length === 0) {
+          throw Object.assign(new Error("ENOENT"), { code: 2 });
+        }
+        return { size: remote.length };
+      },
+      chmod: async (...args) => { chmods.push(args); },
+      rename: async () => { promoted = true; },
+      delete: async () => {},
+    };
+    transferBridge.init({ sftpClients: new Map([["source", sourceClient], ["target", targetClient]]) });
+    const localStage = tempDirBridge.getTransferTempFilePath(transferId, "payload.bin");
+    t.after(async () => fs.promises.rm(localStage, { force: true }));
+    const sender = createSender();
+    const result = await transferBridge.startTransfer({ sender }, {
+      transferId,
+      sourcePath: "/source/payload.bin",
+      targetPath: "/target/payload.bin",
+      sourceType: "sftp", targetType: "sftp",
+      sourceSftpId: "source", targetSftpId: "target",
+      sourceEncoding: "utf-8", targetEncoding: "utf-8",
+      totalBytes: payload.length,
+      sameHost: true, resumable: false,
+    });
+    assert.equal(result.error, undefined, result.error);
+    assert.deepEqual(commands, ["cp -a '/source/payload.bin' '/target/payload.bin'"]);
+    assert.equal(sender.sent.some(entry => entry.channel === "netcatty:transfer:complete"), true);
+    if (cpResult === 0) {
+      assert.deepEqual(chmods, [], "fresh cp must not restore destination permissions");
+      assert.equal(reads, 0, "successful cp must not download the source");
+      assert.equal(remote.length, 0, "successful cp must not upload through SFTP");
+      assert.equal(fs.existsSync(localStage), false);
+    } else {
+      assert.ok(reads > 0, "cp failure must fall back to SFTP download");
+      assert.deepEqual(remote, payload, "fallback must upload the downloaded contents");
+      assert.equal(promoted, true);
+    }
+  });
+}

vite.config.ts

@@ -111,7 +111,7 @@ export default defineConfig(() => {
       build: {
         // The shared runtime is also required by Electron; convert it for browser builds.
         commonjsOptions: {
-          include: [/node_modules/, /domain\/systemManager\/containerRuntime\.shared\.cjs$/, /domain\/plugin(?:RuntimePolicy|PermissionDescriptions|ThemePack|RemoteTreePolicy|ViewStylePolicy|GitHubRepository)\.cjs$/],
+          include: [/node_modules/, /domain\/sshPublicKey\.shared\.cjs$/, /domain\/systemManager\/containerRuntime\.shared\.cjs$/, /domain\/plugin(?:RuntimePolicy|PermissionDescriptions|ThemePack|RemoteTreePolicy|ViewStylePolicy|GitHubRepository)\.cjs$/],
         },
         chunkSizeWarningLimit: 3000,
         target: 'esnext', // Required for top-level await in WASM modules
@@ -134,6 +134,7 @@ export default defineConfig(() => {
         include: [
           // Keep the renderer alias pre-bundled so dev serves ESM instead of raw CommonJS.
           '@/domain/systemManager/containerRuntime.shared.cjs',
+          '@/domain/sshPublicKey.shared.cjs',
           '@/domain/pluginRuntimePolicy.cjs',
           '@/domain/pluginGitHubRepository.cjs',
           '@/domain/pluginPermissionDescriptions.cjs',