Index: client/pkgr.eagle
==================================================================
--- client/pkgr.eagle
+++ client/pkgr.eagle
@@ -433,10 +433,64 @@
           [namespace current] :: tclMustBeReady]]]
 
       return [eagle $script(outer)]
     }
   }
+
+  proc hookPackageUnknownHandler {} {
+    set varName [appendArgs [getLookupVarNamePrefix] saved_package_unknown]
+
+    if {[info exists $varName]} then {
+      error "package unknown handler already hooked"
+    }
+
+    set $varName [package unknown]
+    package unknown [appendArgs [namespace current] ::packageUnknownHandler]
+  }
+
+  proc unhookPackageUnknownHandler {} {
+    set varName [appendArgs [getLookupVarNamePrefix] saved_package_unknown]
+
+    if {![info exists $varName]} then {
+      error "package unknown handler is not hooked"
+    }
+
+    package unknown [set $varName]
+    unset $varName
+  }
+
+  proc packageUnknownHandler { package {version ""} } {
+    if {[catch {main $package $version} error(1)] == 0} then {
+      return
+    } else {
+      tclLog [appendArgs \
+          "pkgr: new handler failed for \"" $package " " $version \
+          "\", error: " $error(1)]
+    }
+
+    set varName [appendArgs [getLookupVarNamePrefix] saved_package_unknown]
+
+    if {[info exists $varName]} then {
+      set oldHandler [set $varName]
+    } else {
+      set oldHandler ""
+    }
+
+    if {[string length $oldHandler] > 0} then {
+      lappend oldHandler $package $version
+
+      if {[catch {uplevel #0 $oldHandler} error(2)] == 0} then {
+        return
+      } else {
+        tclLog [appendArgs \
+            "pkgr: old handler failed for \"" $package " " $version \
+            "\", error: " $error(2)]
+      }
+    }
+
+    error [array get error]
+  }
 
   proc main { package version } {
     #
     # NOTE: Issue the lookup request to the remote package repository.
     #

Index: client/pkgr.eagle.harpy
==================================================================
--- client/pkgr.eagle.harpy
+++ client/pkgr.eagle.harpy
@@ -19,32 +19,32 @@
 <Certificate xmlns="https://eagle.to/2011/harpy"
              xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
              xmlns:xsd="http://www.w3.org/2001/XMLSchema">
   <Protocol>None</Protocol>
   <Vendor>Mistachkin Systems</Vendor>
-  <Id>9f926fa1-99a4-41ab-bb33-50e8576a6d21</Id>
+  <Id>69cd6be1-1651-4b2b-b188-21b47f431860</Id>
   <HashAlgorithm>SHA512</HashAlgorithm>
   <EntityType>Script</EntityType>
-  <TimeStamp>2016-08-15T05:05:47.5290547Z</TimeStamp>
+  <TimeStamp>2016-08-15T18:30:19.8005391Z</TimeStamp>
   <Duration>-1.00:00:00</Duration>
   <Key>0x2c322765603b5278</Key>
   <Signature>
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   </Signature>
 </Certificate>