diff --git a/resources/celerity/map.php b/resources/celerity/map.php
--- a/resources/celerity/map.php
+++ b/resources/celerity/map.php
@@ -7,7 +7,7 @@
  */
 return array(
   'names' => array(
-    'core.pkg.css' => '04a24e98',
+    'core.pkg.css' => '8815f87d',
     'core.pkg.js' => 'efa12ecc',
     'darkconsole.pkg.js' => '8ab24e01',
     'differential.pkg.css' => '8af45893',
@@ -125,7 +125,7 @@
     'rsrc/css/phui/phui-action-list.css' => '9ee9910a',
     'rsrc/css/phui/phui-box.css' => '7b3a2eed',
     'rsrc/css/phui/phui-button.css' => '008ba5e2',
-    'rsrc/css/phui/phui-crumbs-view.css' => '3e362700',
+    'rsrc/css/phui/phui-crumbs-view.css' => '646a8830',
     'rsrc/css/phui/phui-document.css' => 'bbeb1890',
     'rsrc/css/phui/phui-feed-story.css' => 'c9f3a0b5',
     'rsrc/css/phui/phui-fontkit.css' => '9c3d2dce',
@@ -137,7 +137,7 @@
     'rsrc/css/phui/phui-info-panel.css' => '27ea50a1',
     'rsrc/css/phui/phui-list.css' => '53deb25c',
     'rsrc/css/phui/phui-object-box.css' => '0d47b3c8',
-    'rsrc/css/phui/phui-object-item-list-view.css' => '832c58fe',
+    'rsrc/css/phui/phui-object-item-list-view.css' => '2686a80e',
     'rsrc/css/phui/phui-pinboard-view.css' => '3dd4a269',
     'rsrc/css/phui/phui-property-list-view.css' => '51480060',
     'rsrc/css/phui/phui-remarkup-preview.css' => '19ad512b',
@@ -770,7 +770,7 @@
     'phui-calendar-day-css' => 'de035c8a',
     'phui-calendar-list-css' => 'c1d0ca59',
     'phui-calendar-month-css' => 'a92e47d2',
-    'phui-crumbs-view-css' => '3e362700',
+    'phui-crumbs-view-css' => '646a8830',
     'phui-document-view-css' => 'bbeb1890',
     'phui-feed-story-css' => 'c9f3a0b5',
     'phui-font-icon-base-css' => '3dad2ae3',
@@ -783,7 +783,7 @@
     'phui-info-panel-css' => '27ea50a1',
     'phui-list-view-css' => '53deb25c',
     'phui-object-box-css' => '0d47b3c8',
-    'phui-object-item-list-view-css' => '832c58fe',
+    'phui-object-item-list-view-css' => '2686a80e',
     'phui-pinboard-view-css' => '3dd4a269',
     'phui-property-list-view-css' => '51480060',
     'phui-remarkup-preview-css' => '19ad512b',
diff --git a/scripts/repository/commit_hook.php b/scripts/repository/commit_hook.php
--- a/scripts/repository/commit_hook.php
+++ b/scripts/repository/commit_hook.php
@@ -1,6 +1,15 @@
-#!/usr/bin/env php
+#!/usr/bin/env TERM=dumb php
 <?php
 
+// NOTE: Note that we're specifying TERM=dumb above when invoking the PHP
+// interpreter. This suppresses an error which looks like this:
+//
+//   No entry for terminal type "unknown";
+//   using dumb terminal settings.
+//
+// This arises from somewhere in the PHP startup machinery if TERM is not
+// set to a recognized value.
+
 // Commit hooks execute in an unusual context where the environment may be
 // unavailable, particularly in SVN. The first parameter to this script is
 // either a bare repository identifier ("X"), or a repository identifier
diff --git a/src/applications/diffusion/ssh/DiffusionGitReceivePackSSHWorkflow.php b/src/applications/diffusion/ssh/DiffusionGitReceivePackSSHWorkflow.php
--- a/src/applications/diffusion/ssh/DiffusionGitReceivePackSSHWorkflow.php
+++ b/src/applications/diffusion/ssh/DiffusionGitReceivePackSSHWorkflow.php
@@ -14,9 +14,7 @@
   }
 
   protected function executeRepositoryOperations() {
-    $args = $this->getArgs();
-    $path = head($args->getArg('dir'));
-    $repository = $this->loadRepository($path);
+    $repository = $this->getRepository();
 
     // This is a write, and must have write access.
     $this->requireWriteAccess();
diff --git a/src/applications/diffusion/ssh/DiffusionGitSSHWorkflow.php b/src/applications/diffusion/ssh/DiffusionGitSSHWorkflow.php
--- a/src/applications/diffusion/ssh/DiffusionGitSSHWorkflow.php
+++ b/src/applications/diffusion/ssh/DiffusionGitSSHWorkflow.php
@@ -7,6 +7,12 @@
     return parent::writeError($message."\n");
   }
 
+  protected function identifyRepository() {
+    $args = $this->getArgs();
+    $path = head($args->getArg('dir'));
+    return $this->loadRepositoryWithPath($path);
+  }
+
   protected function waitForGitClient() {
     $io_channel = $this->getIOChannel();
 
diff --git a/src/applications/diffusion/ssh/DiffusionGitUploadPackSSHWorkflow.php b/src/applications/diffusion/ssh/DiffusionGitUploadPackSSHWorkflow.php
--- a/src/applications/diffusion/ssh/DiffusionGitUploadPackSSHWorkflow.php
+++ b/src/applications/diffusion/ssh/DiffusionGitUploadPackSSHWorkflow.php
@@ -14,9 +14,7 @@
   }
 
   protected function executeRepositoryOperations() {
-    $args = $this->getArgs();
-    $path = head($args->getArg('dir'));
-    $repository = $this->loadRepository($path);
+    $repository = $this->getRepository();
 
     $command = csprintf('git-upload-pack -- %s', $repository->getLocalPath());
     $command = PhabricatorDaemon::sudoCommandAsDaemonUser($command);
diff --git a/src/applications/diffusion/ssh/DiffusionMercurialServeSSHWorkflow.php b/src/applications/diffusion/ssh/DiffusionMercurialServeSSHWorkflow.php
--- a/src/applications/diffusion/ssh/DiffusionMercurialServeSSHWorkflow.php
+++ b/src/applications/diffusion/ssh/DiffusionMercurialServeSSHWorkflow.php
@@ -24,11 +24,14 @@
       ));
   }
 
-  protected function executeRepositoryOperations() {
+  protected function identifyRepository() {
     $args = $this->getArgs();
     $path = $args->getArg('repository');
-    $repository = $this->loadRepository($path);
+    return $this->loadRepositoryWithPath($path);
+  }
 
+  protected function executeRepositoryOperations() {
+    $repository = $this->getRepository();
     $args = $this->getArgs();
 
     if (!$args->getArg('stdio')) {
diff --git a/src/applications/diffusion/ssh/DiffusionSSHWorkflow.php b/src/applications/diffusion/ssh/DiffusionSSHWorkflow.php
--- a/src/applications/diffusion/ssh/DiffusionSSHWorkflow.php
+++ b/src/applications/diffusion/ssh/DiffusionSSHWorkflow.php
@@ -8,11 +8,16 @@
 
   public function getRepository() {
     if (!$this->repository) {
-      throw new Exception('Call loadRepository() before getRepository()!');
+      throw new Exception(pht('Repository is not available yet!'));
     }
     return $this->repository;
   }
 
+  private function setRepository(PhabricatorRepository $repository) {
+    $this->repository = $repository;
+    return $this;
+  }
+
   public function getArgs() {
     return $this->args;
   }
@@ -33,6 +38,10 @@
     return $env;
   }
 
+  /**
+   * Identify and load the affected repository.
+   */
+  abstract protected function identifyRepository();
   abstract protected function executeRepositoryOperations();
 
   protected function writeError($message) {
@@ -43,6 +52,12 @@
   final public function execute(PhutilArgumentParser $args) {
     $this->args = $args;
 
+    $repository = $this->identifyRepository();
+    $this->setRepository($repository);
+
+    // TODO: Here, we would make a proxying decision, had I implemented
+    // proxying yet.
+
     try {
       return $this->executeRepositoryOperations();
     } catch (Exception $ex) {
@@ -51,7 +66,7 @@
     }
   }
 
-  protected function loadRepository($path) {
+  protected function loadRepositoryWithPath($path) {
     $viewer = $this->getUser();
 
     $regex = '@^/?diffusion/(?P<callsign>[A-Z]+)(?:/|\z)@';
@@ -88,8 +103,6 @@
           pht('This repository is not available over SSH.'));
     }
 
-    $this->repository = $repository;
-
     return $repository;
   }
 
diff --git a/src/applications/diffusion/ssh/DiffusionSubversionServeSSHWorkflow.php b/src/applications/diffusion/ssh/DiffusionSubversionServeSSHWorkflow.php
--- a/src/applications/diffusion/ssh/DiffusionSubversionServeSSHWorkflow.php
+++ b/src/applications/diffusion/ssh/DiffusionSubversionServeSSHWorkflow.php
@@ -20,6 +20,12 @@
 
   private $internalBaseURI;
   private $externalBaseURI;
+  private $peekBuffer;
+  private $command;
+
+  private function getCommand() {
+    return $this->command;
+  }
 
   protected function didConstruct() {
     $this->setName('svnserve');
@@ -32,7 +38,107 @@
       ));
   }
 
+  protected function identifyRepository() {
+    // NOTE: In SVN, we need to read the first few protocol frames before we
+    // can determine which repository the user is trying to access. We're
+    // going to peek at the data on the wire to identify the repository.
+
+    $io_channel = $this->getIOChannel();
+
+    // Before the client will send us the first protocol frame, we need to send
+    // it a connection frame with server capabilities. To figure out the
+    // correct frame we're going to start `svnserve`, read the frame from it,
+    // send it to the client, then kill the subprocess.
+
+    // TODO: This is pretty inelegant and the protocol frame will change very
+    // rarely. We could cache it if we can find a reasonable way to dirty the
+    // cache.
+
+    $command = csprintf('svnserve -t');
+    $command = PhabricatorDaemon::sudoCommandAsDaemonUser($command);
+    $future = new ExecFuture('%C', $command);
+    $exec_channel = new PhutilExecChannel($future);
+    $exec_protocol = new DiffusionSubversionWireProtocol();
+
+    while (true) {
+      PhutilChannel::waitForAny(array($exec_channel));
+      $exec_channel->update();
+
+      $exec_message = $exec_channel->read();
+      if ($exec_message !== null) {
+        $messages = $exec_protocol->writeData($exec_message);
+        if ($messages) {
+          $message = head($messages);
+          $raw = $message['raw'];
+
+          // Write the greeting frame to the client.
+          $io_channel->write($raw);
+
+          // Kill the subprocess.
+          $future->resolveKill();
+          break;
+        }
+      }
+
+      if (!$exec_channel->isOpenForReading()) {
+        throw new Exception(
+          pht(
+            'svnserve subprocess exited before emitting a protocol frame.'));
+      }
+    }
+
+    $io_protocol = new DiffusionSubversionWireProtocol();
+    while (true) {
+      PhutilChannel::waitForAny(array($io_channel));
+      $io_channel->update();
+
+      $in_message = $io_channel->read();
+      if ($in_message !== null) {
+        $this->peekBuffer .= $in_message;
+        if (strlen($this->peekBuffer) > (1024 * 1024)) {
+          throw new Exception(
+            pht(
+              'Client transmitted more than 1MB of data without transmitting '.
+              'a recognizable protocol frame.'));
+        }
+
+        $messages = $io_protocol->writeData($in_message);
+        if ($messages) {
+          $message = head($messages);
+          $struct = $message['structure'];
+
+          // This is the:
+          //
+          //   ( version ( cap1 ... ) url ... )
+          //
+          // The `url` allows us to identify the repository.
+
+          $uri = $struct[2]['value'];
+          $path = $this->getPathFromSubversionURI($uri);
+
+          return $this->loadRepositoryWithPath($path);
+        }
+      }
+
+      if (!$io_channel->isOpenForReading()) {
+        throw new Exception(
+          pht(
+            'Client closed connection before sending a complete protocol '.
+            'frame.'));
+      }
+
+      // If the client has disconnected, kill the subprocess and bail.
+      if (!$io_channel->isOpenForWriting()) {
+        throw new Exception(
+          pht(
+            'Client closed connection before receiving response.'));
+      }
+    }
+  }
+
   protected function executeRepositoryOperations() {
+    $repository = $this->getRepository();
+
     $args = $this->getArgs();
     if (!$args->getArg('tunnel')) {
       throw new Exception('Expected `svnserve -t`!');
@@ -48,12 +154,15 @@
     $this->inProtocol = new DiffusionSubversionWireProtocol();
     $this->outProtocol = new DiffusionSubversionWireProtocol();
 
-    $err = id($this->newPassthruCommand())
+    $this->command = id($this->newPassthruCommand())
       ->setIOChannel($this->getIOChannel())
       ->setCommandChannelFromExecFuture($future)
       ->setWillWriteCallback(array($this, 'willWriteMessageCallback'))
-      ->setWillReadCallback(array($this, 'willReadMessageCallback'))
-      ->execute();
+      ->setWillReadCallback(array($this, 'willReadMessageCallback'));
+
+    $this->command->setPauseIOReads(true);
+
+    $err = $this->command->execute();
 
     if (!$err && $this->didSeeWrite) {
       $this->getRepository()->writeStatusMessage(
@@ -161,6 +270,19 @@
           switch ($this->outPhaseCount) {
             case 0:
               // This is the "greeting", which announces capabilities.
+
+              // We already sent this when we were figuring out which
+              // repository this request is for, so we aren't going to send
+              // it again.
+
+              // Instead, we're going to replay the client's response (which
+              // we also already read).
+
+              $command = $this->getCommand();
+              $command->writeIORead($this->peekBuffer);
+              $command->setPauseIOReads(false);
+
+              $message_raw = null;
               break;
             case 1:
               // This responds to the client greeting, and announces auth.
@@ -203,7 +325,9 @@
 
       }
 
-      $result[] = $message_raw;
+      if ($message_raw !== null) {
+        $result[] = $message_raw;
+      }
     }
 
     if (!$result) {
@@ -213,7 +337,7 @@
     return implode('', $result);
   }
 
-  private function makeInternalURI($uri_string) {
+  private function getPathFromSubversionURI($uri_string) {
     $uri = new PhutilURI($uri_string);
 
     $proto = $uri->getProtocol();
@@ -223,11 +347,10 @@
           'Protocol for URI "%s" MUST be "svn+ssh".',
           $uri_string));
     }
-
     $path = $uri->getPath();
 
     // Subversion presumably deals with this, but make sure there's nothing
-    // skethcy going on with the URI.
+    // sketchy going on with the URI.
     if (preg_match('(/\\.\\./)', $path)) {
       throw new Exception(
         pht(
@@ -235,8 +358,17 @@
           $uri_string));
     }
 
-    $repository = $this->loadRepository($path);
+    $path = $this->normalizeSVNPath($path);
 
+    return $path;
+  }
+
+  private function makeInternalURI($uri_string) {
+    $uri = new PhutilURI($uri_string);
+
+    $repository = $this->getRepository();
+
+    $path = $this->getPathFromSubversionURI($uri_string);
     $path = preg_replace(
       '(^/diffusion/[A-Z]+)',
       rtrim($repository->getLocalPath(), '/'),
@@ -246,14 +378,25 @@
       $path = rtrim($path, '/');
     }
 
+    // NOTE: We are intentionally NOT removing username information from the
+    // URI. Subversion retains it over the course of the request and considers
+    // two repositories with different username identifiers to be distinct and
+    // incompatible.
+
     $uri->setPath($path);
 
     // If this is happening during the handshake, these are the base URIs for
     // the request.
     if ($this->externalBaseURI === null) {
       $pre = (string)id(clone $uri)->setPath('');
-      $this->externalBaseURI = $pre.'/diffusion/'.$repository->getCallsign();
-      $this->internalBaseURI = $pre.rtrim($repository->getLocalPath(), '/');
+
+      $external_path = '/diffusion/'.$repository->getCallsign();
+      $external_path = $this->normalizeSVNPath($external_path);
+      $this->externalBaseURI = $pre.$external_path;
+
+      $internal_path = rtrim($repository->getLocalPath(), '/');
+      $internal_path = $this->normalizeSVNPath($internal_path);
+      $this->internalBaseURI = $pre.$internal_path;
     }
 
     return (string)$uri;
@@ -270,4 +413,12 @@
     return $uri;
   }
 
+  private function normalizeSVNPath($path) {
+    // Subversion normalizes redundant slashes internally, so normalize them
+    // here as well to make sure things match up.
+    $path = preg_replace('(/+)', '/', $path);
+
+    return $path;
+  }
+
 }
diff --git a/src/infrastructure/ssh/PhabricatorSSHPassthruCommand.php b/src/infrastructure/ssh/PhabricatorSSHPassthruCommand.php
--- a/src/infrastructure/ssh/PhabricatorSSHPassthruCommand.php
+++ b/src/infrastructure/ssh/PhabricatorSSHPassthruCommand.php
@@ -43,6 +43,7 @@
   private $execFuture;
   private $willWriteCallback;
   private $willReadCallback;
+  private $pauseIOReads;
 
   public function setCommandChannelFromExecFuture(ExecFuture $exec_future) {
     $exec_channel = new PhutilExecChannel($exec_future);
@@ -78,6 +79,11 @@
     $this->errorChannel->write($data);
   }
 
+  public function setPauseIOReads($pause) {
+    $this->pauseIOReads = $pause;
+    return $this;
+  }
+
   public function execute() {
     $command_channel = $this->commandChannel;
     $io_channel = $this->ioChannel;
@@ -140,16 +146,15 @@
       $done = !$command_channel->isOpenForReading() &&
                $command_channel->isReadBufferEmpty();
 
-      $in_message = $io_channel->read();
-      if ($in_message !== null) {
-        $in_message = $this->willWriteData($in_message);
+      if (!$this->pauseIOReads) {
+        $in_message = $io_channel->read();
         if ($in_message !== null) {
-          $command_channel->write($in_message);
+          $this->writeIORead($in_message);
         }
       }
 
       $out_message = $command_channel->read();
-      if ($out_message !== null) {
+      if (strlen($out_message)) {
         $out_message = $this->willReadData($out_message);
         if ($out_message !== null) {
           $io_channel->write($out_message);
@@ -185,6 +190,13 @@
     return $err;
   }
 
+  public function writeIORead($in_message) {
+    $in_message = $this->willWriteData($in_message);
+    if (strlen($in_message)) {
+      $this->commandChannel->write($in_message);
+    }
+  }
+
   public function willWriteData($message) {
     if ($this->willWriteCallback) {
       return call_user_func($this->willWriteCallback, $this, $message);