diff --git a/Dockerfile b/Dockerfile
index 42dca5e..b79e6fc 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -41,8 +41,8 @@ RUN rm -rf .git build vm src misc Factor.app \
     GNUmakefile Nmakefile LICENSE.txt README.md \
     build.sh build.cmd unmaintained
 
-# Keep only the extra/ source that sequences.extras needs to compile on demand:
-# itself plus extra/assocs.extras and extra/shuffle.
+# Keep only the extra/ source needed to compile sequences.extras and
+# assocs.extras on demand: those two plus extra/shuffle.
 RUN find extra -mindepth 1 -maxdepth 1 \
     ! -name sequences ! -name assocs ! -name shuffle \
     -exec rm -rf {} + && \
diff --git a/bin/run.sh b/bin/run.sh
index 6f069de..f45edc9 100755
--- a/bin/run.sh
+++ b/bin/run.sh
@@ -47,7 +47,11 @@ tmp_dir=$(mktemp -d -t "factor-runner-${slug}-XXXXX")
 trap 'rm -rf "${tmp_dir}"' EXIT
 cp -r "${solution_dir}/." "${tmp_dir}"
 stripped_tests="${tmp_dir}/${slug}/${slug}-tests.factor"
-awk '!/^STOP-HERE$/' "${stripped_tests}" > "${stripped_tests}.new"
+# Blank each STOP-HERE line rather than deleting it: a blank line is a no-op
+# to Factor, and keeping the line count intact means the line numbers Factor
+# reports for failures still match the file the student submitted.
+awk '{ if ($0 ~ /^STOP-HERE$/) print ""; else print }' \
+    "${stripped_tests}" > "${stripped_tests}.new"
 mv "${stripped_tests}.new" "${stripped_tests}"
 
 # Run Factor; capture combined stdout/stderr.
@@ -131,7 +135,7 @@ src_tests=$(awk "${awk_json}"'
 
 # 2. Parse Factor stdout into NDJSON segments and failures:
 #    segments: {"type":"segment","idx":N,"failed":bool,"name":"...","output":"..."}
-#    failures: {"type":"failure","line_no":N,"message":"..."}
+#    failures: {"type":"failure","line_no":N,"location":"...","message":"..."}
 parsed=$(printf '%s\n' "${raw_output}" | awk "${awk_json}"'
     function close_segment(   out, i) {
         if (idx == 0) return
@@ -147,8 +151,8 @@ parsed=$(printf '%s\n' "${raw_output}" | awk "${awk_json}"'
         for (i = 1; i <= fail_n; i++) body = body (i > 1 ? "\n" : "") fail[i]
         sub(/^\n+/, "", body)
         sub(/\n+$/, "", body)
-        printf "{\"type\":\"failure\",\"line_no\":%d,\"message\":%s}\n",
-            fail_line, json_str(body)
+        printf "{\"type\":\"failure\",\"line_no\":%d,\"location\":%s,\"message\":%s}\n",
+            fail_line, json_str(fail_loc), json_str(body)
     }
     # Factor renders each test-word name into a title, e.g.:
     #   unit-test            → "Unit Test:"
@@ -221,8 +225,14 @@ parsed=$(printf '%s\n' "${raw_output}" | awk "${awk_json}"'
             n = substr($0, RSTART, RLENGTH)
             gsub(/[^0-9]/, "", n)
             fail_line = n + 0
+            # exercism-tools prints "<path>: <line#>"; collapse it to the
+            # conventional "<path>:<line#>" so the student can paste it
+            # into an editor. The path is already relative to the solution
+            # root, so it is safe to show as-is.
+            fail_loc = substr($0, 1, RSTART - 1) ":" fail_line
         } else {
             fail_line = 0
+            fail_loc = ""
         }
         fail_n = 0
         delete fail
@@ -276,7 +286,7 @@ jq -n \
     --argjson segs   "$(printf '%s\n' "${segments}"   | jq -s '.')" \
     --argjson fails  "$(printf '%s\n' "${failures}"   | jq -s '.')" \
     '
-    ($fails | map({(.line_no|tostring): .message}) | add // {}) as $fail_by_line
+    ($fails | map({(.line_no|tostring): .}) | add // {}) as $fail_by_line
     | $segs | sort_by(.idx)
     | to_entries
     | map(
@@ -284,7 +294,8 @@ jq -n \
         | (.key) as $i
         | ($srcs[$i] // null) as $src
         | ($src.line_no | tostring) as $ln
-        | ($fail_by_line[$ln] // null) as $msg
+        | ($fail_by_line[$ln] // null) as $fail
+        | ($fail.message // null) as $msg
         | (
             if $seg.failed then
                 if ($msg // "" | startswith("=== Expected:")) then "fail"
@@ -300,7 +311,11 @@ jq -n \
             test_code: ($src.test_code // ""),
           }
           + (if $src.task_id then {task_id: $src.task_id} else {} end)
-          + (if $seg.failed then {message: ($msg // "test failed")} else {} end)
+          + (if $seg.failed then
+               {message: (if $msg == null then "test failed"
+                          elif ($fail.location // "") == "" then $msg
+                          else $fail.location + "\n" + $msg end)}
+             else {} end)
           + (if $seg.output != "" then {output: ($seg.output[0:500])} else {} end)
       )
     | (if all(.status == "pass") then "pass" else "fail" end) as $top
diff --git a/tests/all-fail/exercism-tools/exercism-tools.factor b/tests/all-fail/exercism-tools/exercism-tools.factor
index 428c2d3..df5f692 100644
--- a/tests/all-fail/exercism-tools/exercism-tools.factor
+++ b/tests/all-fail/exercism-tools/exercism-tools.factor
@@ -1,6 +1,7 @@
 USING: accessors command-line continuations debugger io kernel
-       lexer namespaces sequences source-files.errors.debugger
-       system tools.test vocabs vocabs.loader ;
+       lexer namespaces prettyprint.config sequences
+       source-files.errors.debugger system tools.test vocabs
+       vocabs.loader ;
 IN: exercism-tools
 
 SYNTAX: STOP-HERE
@@ -9,19 +10,15 @@ SYNTAX: STOP-HERE
 SYNTAX: TASK:
     lexer get next-line ;
 
-! Label the test that follows with its description. The marker lets the
-! wrapper strip this line from captured output and attach it to the next
-! test as a name, rather than leaving it in the previous test's output.
+! Label the test that follows with its description.
 : description ( str -- )
     "###DESC### " write print ;
 
-! Print one failure block in a stable, parser-friendly form. Bracketed by
-! markers so a wrapper can split the stream reliably and avoid Factor's
-! noisy callstack output (which is interleaved with subsequent failures).
+! Print one failure block in a stable, parser-friendly form.
 :: print-failure ( failure -- )
     "###FAIL_BEGIN###" print
     failure error-location print
-    failure error>> [ error. ] [ 2drop ] recover
+    [ failure error>> [ error. ] [ 2drop ] recover ] without-limits
     "###FAIL_END###" print
     flush ;
 
@@ -29,6 +26,7 @@ SYNTAX: TASK:
     test-failures get [ print-failure ] each ;
 
 : run-exercism-tests ( -- )
+    vocab-roots [ "." prefix ] change-global
     command-line get first
     [ require ] [ test ] bi
     test-failures get empty?
diff --git a/tests/all-fail/expected_results.json b/tests/all-fail/expected_results.json
index 07f910b..e6f9bb2 100644
--- a/tests/all-fail/expected_results.json
+++ b/tests/all-fail/expected_results.json
@@ -6,13 +6,13 @@
       "name": "greet returns hello",
       "status": "fail",
       "test_code": "{ \"hello\" } [ greet ] unit-test",
-      "message": "=== Expected:\n\"hello\"\n=== Got:\n\"wrong\""
+      "message": "all-fail/all-fail-tests.factor:5\n=== Expected:\n\"hello\"\n=== Got:\n\"wrong\""
     },
     {
       "name": "greet returns world",
       "status": "fail",
       "test_code": "{ \"world\" } [ greet ] unit-test",
-      "message": "=== Expected:\n\"world\"\n=== Got:\n\"wrong\""
+      "message": "all-fail/all-fail-tests.factor:10\n=== Expected:\n\"world\"\n=== Got:\n\"wrong\""
     }
   ]
 }
diff --git a/tests/concept-concurrency/exercism-tools/exercism-tools.factor b/tests/concept-concurrency/exercism-tools/exercism-tools.factor
index 428c2d3..df5f692 100644
--- a/tests/concept-concurrency/exercism-tools/exercism-tools.factor
+++ b/tests/concept-concurrency/exercism-tools/exercism-tools.factor
@@ -1,6 +1,7 @@
 USING: accessors command-line continuations debugger io kernel
-       lexer namespaces sequences source-files.errors.debugger
-       system tools.test vocabs vocabs.loader ;
+       lexer namespaces prettyprint.config sequences
+       source-files.errors.debugger system tools.test vocabs
+       vocabs.loader ;
 IN: exercism-tools
 
 SYNTAX: STOP-HERE
@@ -9,19 +10,15 @@ SYNTAX: STOP-HERE
 SYNTAX: TASK:
     lexer get next-line ;
 
-! Label the test that follows with its description. The marker lets the
-! wrapper strip this line from captured output and attach it to the next
-! test as a name, rather than leaving it in the previous test's output.
+! Label the test that follows with its description.
 : description ( str -- )
     "###DESC### " write print ;
 
-! Print one failure block in a stable, parser-friendly form. Bracketed by
-! markers so a wrapper can split the stream reliably and avoid Factor's
-! noisy callstack output (which is interleaved with subsequent failures).
+! Print one failure block in a stable, parser-friendly form.
 :: print-failure ( failure -- )
     "###FAIL_BEGIN###" print
     failure error-location print
-    failure error>> [ error. ] [ 2drop ] recover
+    [ failure error>> [ error. ] [ 2drop ] recover ] without-limits
     "###FAIL_END###" print
     flush ;
 
@@ -29,6 +26,7 @@ SYNTAX: TASK:
     test-failures get [ print-failure ] each ;
 
 : run-exercism-tests ( -- )
+    vocab-roots [ "." prefix ] change-global
     command-line get first
     [ require ] [ test ] bi
     test-failures get empty?
diff --git a/tests/concept-multiline/exercism-tools/exercism-tools.factor b/tests/concept-multiline/exercism-tools/exercism-tools.factor
index 428c2d3..df5f692 100644
--- a/tests/concept-multiline/exercism-tools/exercism-tools.factor
+++ b/tests/concept-multiline/exercism-tools/exercism-tools.factor
@@ -1,6 +1,7 @@
 USING: accessors command-line continuations debugger io kernel
-       lexer namespaces sequences source-files.errors.debugger
-       system tools.test vocabs vocabs.loader ;
+       lexer namespaces prettyprint.config sequences
+       source-files.errors.debugger system tools.test vocabs
+       vocabs.loader ;
 IN: exercism-tools
 
 SYNTAX: STOP-HERE
@@ -9,19 +10,15 @@ SYNTAX: STOP-HERE
 SYNTAX: TASK:
     lexer get next-line ;
 
-! Label the test that follows with its description. The marker lets the
-! wrapper strip this line from captured output and attach it to the next
-! test as a name, rather than leaving it in the previous test's output.
+! Label the test that follows with its description.
 : description ( str -- )
     "###DESC### " write print ;
 
-! Print one failure block in a stable, parser-friendly form. Bracketed by
-! markers so a wrapper can split the stream reliably and avoid Factor's
-! noisy callstack output (which is interleaved with subsequent failures).
+! Print one failure block in a stable, parser-friendly form.
 :: print-failure ( failure -- )
     "###FAIL_BEGIN###" print
     failure error-location print
-    failure error>> [ error. ] [ 2drop ] recover
+    [ failure error>> [ error. ] [ 2drop ] recover ] without-limits
     "###FAIL_END###" print
     flush ;
 
@@ -29,6 +26,7 @@ SYNTAX: TASK:
     test-failures get [ print-failure ] each ;
 
 : run-exercism-tests ( -- )
+    vocab-roots [ "." prefix ] change-global
     command-line get first
     [ require ] [ test ] bi
     test-failures get empty?
diff --git a/tests/concept-multiline/expected_results.json b/tests/concept-multiline/expected_results.json
index e4d3e49..f6a6e84 100644
--- a/tests/concept-multiline/expected_results.json
+++ b/tests/concept-multiline/expected_results.json
@@ -73,7 +73,7 @@
       "status": "fail",
       "test_code": "{ 6 } [ 4 [ 6 roll-die ] play-seeded ] unit-test",
       "task_id": 5,
-      "message": "=== Expected:\n6\n=== Got:\n2"
+      "message": "concept-multiline/concept-multiline-tests.factor:62\n=== Expected:\n6\n=== Got:\n2"
     },
     {
       "name": "Test 13",
diff --git a/tests/concept-not-parsing/exercism-tools/exercism-tools.factor b/tests/concept-not-parsing/exercism-tools/exercism-tools.factor
index 428c2d3..df5f692 100644
--- a/tests/concept-not-parsing/exercism-tools/exercism-tools.factor
+++ b/tests/concept-not-parsing/exercism-tools/exercism-tools.factor
@@ -1,6 +1,7 @@
 USING: accessors command-line continuations debugger io kernel
-       lexer namespaces sequences source-files.errors.debugger
-       system tools.test vocabs vocabs.loader ;
+       lexer namespaces prettyprint.config sequences
+       source-files.errors.debugger system tools.test vocabs
+       vocabs.loader ;
 IN: exercism-tools
 
 SYNTAX: STOP-HERE
@@ -9,19 +10,15 @@ SYNTAX: STOP-HERE
 SYNTAX: TASK:
     lexer get next-line ;
 
-! Label the test that follows with its description. The marker lets the
-! wrapper strip this line from captured output and attach it to the next
-! test as a name, rather than leaving it in the previous test's output.
+! Label the test that follows with its description.
 : description ( str -- )
     "###DESC### " write print ;
 
-! Print one failure block in a stable, parser-friendly form. Bracketed by
-! markers so a wrapper can split the stream reliably and avoid Factor's
-! noisy callstack output (which is interleaved with subsequent failures).
+! Print one failure block in a stable, parser-friendly form.
 :: print-failure ( failure -- )
     "###FAIL_BEGIN###" print
     failure error-location print
-    failure error>> [ error. ] [ 2drop ] recover
+    [ failure error>> [ error. ] [ 2drop ] recover ] without-limits
     "###FAIL_END###" print
     flush ;
 
@@ -29,6 +26,7 @@ SYNTAX: TASK:
     test-failures get [ print-failure ] each ;
 
 : run-exercism-tests ( -- )
+    vocab-roots [ "." prefix ] change-global
     command-line get first
     [ require ] [ test ] bi
     test-failures get empty?
diff --git a/tests/concept-not-parsing/expected_results.json b/tests/concept-not-parsing/expected_results.json
index 375be78..b18f740 100644
--- a/tests/concept-not-parsing/expected_results.json
+++ b/tests/concept-not-parsing/expected_results.json
@@ -1,5 +1,5 @@
 {
   "version": 3,
   "status": "error",
-  "message": "/opt/test-runner/tests/concept-not-parsing/concept-not-parsing/concept-not-parsing.factor\n\n6: : cube ( n -- n^3 ) ?!?! ;\n                           ^\nNo word named '?!?!' found in current vocabulary search path"
+  "message": "concept-not-parsing/concept-not-parsing.factor\n\n6: : cube ( n -- n^3 ) ?!?! ;\n                           ^\nNo word named '?!?!' found in current vocabulary search path"
 }
diff --git a/tests/concept-partial-fail/exercism-tools/exercism-tools.factor b/tests/concept-partial-fail/exercism-tools/exercism-tools.factor
index 428c2d3..df5f692 100644
--- a/tests/concept-partial-fail/exercism-tools/exercism-tools.factor
+++ b/tests/concept-partial-fail/exercism-tools/exercism-tools.factor
@@ -1,6 +1,7 @@
 USING: accessors command-line continuations debugger io kernel
-       lexer namespaces sequences source-files.errors.debugger
-       system tools.test vocabs vocabs.loader ;
+       lexer namespaces prettyprint.config sequences
+       source-files.errors.debugger system tools.test vocabs
+       vocabs.loader ;
 IN: exercism-tools
 
 SYNTAX: STOP-HERE
@@ -9,19 +10,15 @@ SYNTAX: STOP-HERE
 SYNTAX: TASK:
     lexer get next-line ;
 
-! Label the test that follows with its description. The marker lets the
-! wrapper strip this line from captured output and attach it to the next
-! test as a name, rather than leaving it in the previous test's output.
+! Label the test that follows with its description.
 : description ( str -- )
     "###DESC### " write print ;
 
-! Print one failure block in a stable, parser-friendly form. Bracketed by
-! markers so a wrapper can split the stream reliably and avoid Factor's
-! noisy callstack output (which is interleaved with subsequent failures).
+! Print one failure block in a stable, parser-friendly form.
 :: print-failure ( failure -- )
     "###FAIL_BEGIN###" print
     failure error-location print
-    failure error>> [ error. ] [ 2drop ] recover
+    [ failure error>> [ error. ] [ 2drop ] recover ] without-limits
     "###FAIL_END###" print
     flush ;
 
@@ -29,6 +26,7 @@ SYNTAX: TASK:
     test-failures get [ print-failure ] each ;
 
 : run-exercism-tests ( -- )
+    vocab-roots [ "." prefix ] change-global
     command-line get first
     [ require ] [ test ] bi
     test-failures get empty?
diff --git a/tests/concept-partial-fail/expected_results.json b/tests/concept-partial-fail/expected_results.json
index 6a1c31c..ccea9fa 100644
--- a/tests/concept-partial-fail/expected_results.json
+++ b/tests/concept-partial-fail/expected_results.json
@@ -21,7 +21,7 @@
       "status": "fail",
       "test_code": "{ 27 } [ \"cubing 3\" print 3 cube ] unit-test",
       "task_id": 2,
-      "message": "=== Expected:\n27\n=== Got:\n12",
+      "message": "concept-partial-fail/concept-partial-fail-tests.factor:12\n=== Expected:\n27\n=== Got:\n12",
       "output": "cubing 3"
     },
     {
@@ -29,42 +29,42 @@
       "status": "fail",
       "test_code": "{ 64 } [ 4 cube ] unit-test",
       "task_id": 2,
-      "message": "=== Expected:\n64\n=== Got:\n20"
+      "message": "concept-partial-fail/concept-partial-fail-tests.factor:13\n=== Expected:\n64\n=== Got:\n20"
     },
     {
       "name": "Test 5",
       "status": "error",
       "test_code": "{ { } } [ { } but-first ] unit-test",
       "task_id": 3,
-      "message": "Cannot create slice: from > to\nfrom 1\nto   0\nseq  { }"
+      "message": "concept-partial-fail/concept-partial-fail-tests.factor:16\nCannot create slice: from > to\nfrom 1\nto   0\nseq  { }"
     },
     {
       "name": "Test 6",
       "status": "error",
       "test_code": "{ 0 } [ 4 0 / ] unit-test",
       "task_id": 4,
-      "message": "Division by zero\nx 4"
+      "message": "concept-partial-fail/concept-partial-fail-tests.factor:19\nDivision by zero\nx 4"
     },
     {
       "name": "Test 7",
       "status": "error",
       "test_code": "{ 0 } [ 10 { 1 2 3 } nth ] unit-test",
       "task_id": 5,
-      "message": "Sequence index out of bounds\nindex 10\nseq   { 1 2 3 }"
+      "message": "concept-partial-fail/concept-partial-fail-tests.factor:22\nSequence index out of bounds\nindex 10\nseq   { 1 2 3 }"
     },
     {
       "name": "Test 8",
       "status": "error",
       "test_code": "{ \"text\" } [ 5 label ] unit-test",
       "task_id": 6,
-      "message": "Generic word label does not define a method for the fixnum class.\nDispatching on object: 5"
+      "message": "concept-partial-fail/concept-partial-fail-tests.factor:25\nGeneric word label does not define a method for the fixnum class.\nDispatching on object: 5"
     },
     {
       "name": "Test 9",
       "status": "error",
       "test_code": "{ 0 } [ 5 [ drop ] call( x -- x ) ] unit-test",
       "task_id": 7,
-      "message": "Quotation's stack effect does not match call site\nquot      [ drop ]\ncall-site ( x -- x )"
+      "message": "concept-partial-fail/concept-partial-fail-tests.factor:28\nQuotation's stack effect does not match call site\nquot      [ drop ]\ncall-site ( x -- x )"
     }
   ]
 }
diff --git a/tests/concept-stub/exercism-tools/exercism-tools.factor b/tests/concept-stub/exercism-tools/exercism-tools.factor
index 428c2d3..df5f692 100644
--- a/tests/concept-stub/exercism-tools/exercism-tools.factor
+++ b/tests/concept-stub/exercism-tools/exercism-tools.factor
@@ -1,6 +1,7 @@
 USING: accessors command-line continuations debugger io kernel
-       lexer namespaces sequences source-files.errors.debugger
-       system tools.test vocabs vocabs.loader ;
+       lexer namespaces prettyprint.config sequences
+       source-files.errors.debugger system tools.test vocabs
+       vocabs.loader ;
 IN: exercism-tools
 
 SYNTAX: STOP-HERE
@@ -9,19 +10,15 @@ SYNTAX: STOP-HERE
 SYNTAX: TASK:
     lexer get next-line ;
 
-! Label the test that follows with its description. The marker lets the
-! wrapper strip this line from captured output and attach it to the next
-! test as a name, rather than leaving it in the previous test's output.
+! Label the test that follows with its description.
 : description ( str -- )
     "###DESC### " write print ;
 
-! Print one failure block in a stable, parser-friendly form. Bracketed by
-! markers so a wrapper can split the stream reliably and avoid Factor's
-! noisy callstack output (which is interleaved with subsequent failures).
+! Print one failure block in a stable, parser-friendly form.
 :: print-failure ( failure -- )
     "###FAIL_BEGIN###" print
     failure error-location print
-    failure error>> [ error. ] [ 2drop ] recover
+    [ failure error>> [ error. ] [ 2drop ] recover ] without-limits
     "###FAIL_END###" print
     flush ;
 
@@ -29,6 +26,7 @@ SYNTAX: TASK:
     test-failures get [ print-failure ] each ;
 
 : run-exercism-tests ( -- )
+    vocab-roots [ "." prefix ] change-global
     command-line get first
     [ require ] [ test ] bi
     test-failures get empty?
diff --git a/tests/concept-stub/expected_results.json b/tests/concept-stub/expected_results.json
index 7f17360..1cdee9b 100644
--- a/tests/concept-stub/expected_results.json
+++ b/tests/concept-stub/expected_results.json
@@ -7,28 +7,28 @@
       "status": "error",
       "test_code": "{ 9 } [ 3 square ] unit-test",
       "task_id": 1,
-      "message": "unimplemented"
+      "message": "concept-stub/concept-stub-tests.factor:5\nunimplemented"
     },
     {
       "name": "Test 2",
       "status": "error",
       "test_code": "{ 16 } [ 4 square ] unit-test",
       "task_id": 1,
-      "message": "unimplemented"
+      "message": "concept-stub/concept-stub-tests.factor:9\nunimplemented"
     },
     {
       "name": "Test 3",
       "status": "error",
       "test_code": "{ 27 } [ 3 cube ] unit-test",
       "task_id": 2,
-      "message": "unimplemented"
+      "message": "concept-stub/concept-stub-tests.factor:12\nunimplemented"
     },
     {
       "name": "Test 4",
       "status": "error",
       "test_code": "{ 64 } [ 4 cube ] unit-test",
       "task_id": 2,
-      "message": "unimplemented"
+      "message": "concept-stub/concept-stub-tests.factor:13\nunimplemented"
     }
   ]
 }
diff --git a/tests/concept-success/exercism-tools/exercism-tools.factor b/tests/concept-success/exercism-tools/exercism-tools.factor
index 428c2d3..df5f692 100644
--- a/tests/concept-success/exercism-tools/exercism-tools.factor
+++ b/tests/concept-success/exercism-tools/exercism-tools.factor
@@ -1,6 +1,7 @@
 USING: accessors command-line continuations debugger io kernel
-       lexer namespaces sequences source-files.errors.debugger
-       system tools.test vocabs vocabs.loader ;
+       lexer namespaces prettyprint.config sequences
+       source-files.errors.debugger system tools.test vocabs
+       vocabs.loader ;
 IN: exercism-tools
 
 SYNTAX: STOP-HERE
@@ -9,19 +10,15 @@ SYNTAX: STOP-HERE
 SYNTAX: TASK:
     lexer get next-line ;
 
-! Label the test that follows with its description. The marker lets the
-! wrapper strip this line from captured output and attach it to the next
-! test as a name, rather than leaving it in the previous test's output.
+! Label the test that follows with its description.
 : description ( str -- )
     "###DESC### " write print ;
 
-! Print one failure block in a stable, parser-friendly form. Bracketed by
-! markers so a wrapper can split the stream reliably and avoid Factor's
-! noisy callstack output (which is interleaved with subsequent failures).
+! Print one failure block in a stable, parser-friendly form.
 :: print-failure ( failure -- )
     "###FAIL_BEGIN###" print
     failure error-location print
-    failure error>> [ error. ] [ 2drop ] recover
+    [ failure error>> [ error. ] [ 2drop ] recover ] without-limits
     "###FAIL_END###" print
     flush ;
 
@@ -29,6 +26,7 @@ SYNTAX: TASK:
     test-failures get [ print-failure ] each ;
 
 : run-exercism-tests ( -- )
+    vocab-roots [ "." prefix ] change-global
     command-line get first
     [ require ] [ test ] bi
     test-failures get empty?
diff --git a/tests/empty-file/exercism-tools/exercism-tools.factor b/tests/empty-file/exercism-tools/exercism-tools.factor
index 428c2d3..df5f692 100644
--- a/tests/empty-file/exercism-tools/exercism-tools.factor
+++ b/tests/empty-file/exercism-tools/exercism-tools.factor
@@ -1,6 +1,7 @@
 USING: accessors command-line continuations debugger io kernel
-       lexer namespaces sequences source-files.errors.debugger
-       system tools.test vocabs vocabs.loader ;
+       lexer namespaces prettyprint.config sequences
+       source-files.errors.debugger system tools.test vocabs
+       vocabs.loader ;
 IN: exercism-tools
 
 SYNTAX: STOP-HERE
@@ -9,19 +10,15 @@ SYNTAX: STOP-HERE
 SYNTAX: TASK:
     lexer get next-line ;
 
-! Label the test that follows with its description. The marker lets the
-! wrapper strip this line from captured output and attach it to the next
-! test as a name, rather than leaving it in the previous test's output.
+! Label the test that follows with its description.
 : description ( str -- )
     "###DESC### " write print ;
 
-! Print one failure block in a stable, parser-friendly form. Bracketed by
-! markers so a wrapper can split the stream reliably and avoid Factor's
-! noisy callstack output (which is interleaved with subsequent failures).
+! Print one failure block in a stable, parser-friendly form.
 :: print-failure ( failure -- )
     "###FAIL_BEGIN###" print
     failure error-location print
-    failure error>> [ error. ] [ 2drop ] recover
+    [ failure error>> [ error. ] [ 2drop ] recover ] without-limits
     "###FAIL_END###" print
     flush ;
 
@@ -29,6 +26,7 @@ SYNTAX: TASK:
     test-failures get [ print-failure ] each ;
 
 : run-exercism-tests ( -- )
+    vocab-roots [ "." prefix ] change-global
     command-line get first
     [ require ] [ test ] bi
     test-failures get empty?
diff --git a/tests/empty-file/expected_results.json b/tests/empty-file/expected_results.json
index 5b7846b..6586f1b 100644
--- a/tests/empty-file/expected_results.json
+++ b/tests/empty-file/expected_results.json
@@ -1,5 +1,5 @@
 {
   "version": 3,
   "status": "error",
-  "message": "/opt/test-runner/tests/empty-file/empty-file/empty-file-tests.factor\n\n5: { \"hello\" } [ greet ] unit-test\n                      ^\nNo word named 'greet' found in current vocabulary search path"
+  "message": "empty-file/empty-file-tests.factor\n\n5: { \"hello\" } [ greet ] unit-test\n                      ^\nNo word named 'greet' found in current vocabulary search path"
 }
diff --git a/tests/partial-fail/exercism-tools/exercism-tools.factor b/tests/partial-fail/exercism-tools/exercism-tools.factor
index 428c2d3..df5f692 100644
--- a/tests/partial-fail/exercism-tools/exercism-tools.factor
+++ b/tests/partial-fail/exercism-tools/exercism-tools.factor
@@ -1,6 +1,7 @@
 USING: accessors command-line continuations debugger io kernel
-       lexer namespaces sequences source-files.errors.debugger
-       system tools.test vocabs vocabs.loader ;
+       lexer namespaces prettyprint.config sequences
+       source-files.errors.debugger system tools.test vocabs
+       vocabs.loader ;
 IN: exercism-tools
 
 SYNTAX: STOP-HERE
@@ -9,19 +10,15 @@ SYNTAX: STOP-HERE
 SYNTAX: TASK:
     lexer get next-line ;
 
-! Label the test that follows with its description. The marker lets the
-! wrapper strip this line from captured output and attach it to the next
-! test as a name, rather than leaving it in the previous test's output.
+! Label the test that follows with its description.
 : description ( str -- )
     "###DESC### " write print ;
 
-! Print one failure block in a stable, parser-friendly form. Bracketed by
-! markers so a wrapper can split the stream reliably and avoid Factor's
-! noisy callstack output (which is interleaved with subsequent failures).
+! Print one failure block in a stable, parser-friendly form.
 :: print-failure ( failure -- )
     "###FAIL_BEGIN###" print
     failure error-location print
-    failure error>> [ error. ] [ 2drop ] recover
+    [ failure error>> [ error. ] [ 2drop ] recover ] without-limits
     "###FAIL_END###" print
     flush ;
 
@@ -29,6 +26,7 @@ SYNTAX: TASK:
     test-failures get [ print-failure ] each ;
 
 : run-exercism-tests ( -- )
+    vocab-roots [ "." prefix ] change-global
     command-line get first
     [ require ] [ test ] bi
     test-failures get empty?
diff --git a/tests/partial-fail/expected_results.json b/tests/partial-fail/expected_results.json
index 9f73a6a..4cdac9f 100644
--- a/tests/partial-fail/expected_results.json
+++ b/tests/partial-fail/expected_results.json
@@ -12,8 +12,14 @@
       "name": "greet returns world",
       "status": "fail",
       "test_code": "{ \"world\" } [ 2 . greet ] unit-test",
-      "message": "=== Expected:\n\"world\"\n=== Got:\n\"hello\"",
+      "message": "partial-fail/partial-fail-tests.factor:10\n=== Expected:\n\"world\"\n=== Got:\n\"hello\"",
       "output": "2"
+    },
+    {
+      "name": "registering the same name twice throws",
+      "status": "error",
+      "test_code": "{ H{ { \"ada\" \"hello\" } } }\n[ H{ } clone \"hello\" \"ada\" register \"world\" \"ada\" register ] unit-test",
+      "message": "partial-fail/partial-fail-tests.factor:14\nkey-exists\nvalue \"ada\"\nkey   H{ { \"ada\" \"hello\" } }\nassoc \"hello\""
     }
   ]
 }
diff --git a/tests/partial-fail/partial-fail/partial-fail-tests.factor b/tests/partial-fail/partial-fail/partial-fail-tests.factor
index 5f7c85b..633fbb3 100644
--- a/tests/partial-fail/partial-fail/partial-fail-tests.factor
+++ b/tests/partial-fail/partial-fail/partial-fail-tests.factor
@@ -1,4 +1,4 @@
-USING: exercism-tools io partial-fail prettyprint tools.test ;
+USING: exercism-tools io kernel partial-fail prettyprint tools.test ;
 IN: partial-fail.tests
 
 "greet returns hello" description
@@ -8,3 +8,7 @@ STOP-HERE
 
 "greet returns world" description
 { "world" } [ 2 . greet ] unit-test
+
+"registering the same name twice throws" description
+{ H{ { "ada" "hello" } } }
+[ H{ } clone "hello" "ada" register "world" "ada" register ] unit-test
diff --git a/tests/partial-fail/partial-fail/partial-fail.factor b/tests/partial-fail/partial-fail/partial-fail.factor
index 427d1d1..3a33c63 100644
--- a/tests/partial-fail/partial-fail/partial-fail.factor
+++ b/tests/partial-fail/partial-fail/partial-fail.factor
@@ -1,4 +1,8 @@
-USING: kernel ;
+USING: assocs.extras kernel ;
 IN: partial-fail
 
 : greet ( -- str ) "hello" ;
+
+! set-once-at throws key-exists when the key is already present
+! (assocs.extras), so registering the same name twice fails at runtime.
+: register ( assoc greeting name -- assoc ) pick set-once-at ;
diff --git a/tests/practice-stub/exercism-tools/exercism-tools.factor b/tests/practice-stub/exercism-tools/exercism-tools.factor
index 428c2d3..df5f692 100644
--- a/tests/practice-stub/exercism-tools/exercism-tools.factor
+++ b/tests/practice-stub/exercism-tools/exercism-tools.factor
@@ -1,6 +1,7 @@
 USING: accessors command-line continuations debugger io kernel
-       lexer namespaces sequences source-files.errors.debugger
-       system tools.test vocabs vocabs.loader ;
+       lexer namespaces prettyprint.config sequences
+       source-files.errors.debugger system tools.test vocabs
+       vocabs.loader ;
 IN: exercism-tools
 
 SYNTAX: STOP-HERE
@@ -9,19 +10,15 @@ SYNTAX: STOP-HERE
 SYNTAX: TASK:
     lexer get next-line ;
 
-! Label the test that follows with its description. The marker lets the
-! wrapper strip this line from captured output and attach it to the next
-! test as a name, rather than leaving it in the previous test's output.
+! Label the test that follows with its description.
 : description ( str -- )
     "###DESC### " write print ;
 
-! Print one failure block in a stable, parser-friendly form. Bracketed by
-! markers so a wrapper can split the stream reliably and avoid Factor's
-! noisy callstack output (which is interleaved with subsequent failures).
+! Print one failure block in a stable, parser-friendly form.
 :: print-failure ( failure -- )
     "###FAIL_BEGIN###" print
     failure error-location print
-    failure error>> [ error. ] [ 2drop ] recover
+    [ failure error>> [ error. ] [ 2drop ] recover ] without-limits
     "###FAIL_END###" print
     flush ;
 
@@ -29,6 +26,7 @@ SYNTAX: TASK:
     test-failures get [ print-failure ] each ;
 
 : run-exercism-tests ( -- )
+    vocab-roots [ "." prefix ] change-global
     command-line get first
     [ require ] [ test ] bi
     test-failures get empty?
diff --git a/tests/practice-stub/expected_results.json b/tests/practice-stub/expected_results.json
index 56de0c1..e9a10e6 100644
--- a/tests/practice-stub/expected_results.json
+++ b/tests/practice-stub/expected_results.json
@@ -6,13 +6,13 @@
       "name": "greet returns hello",
       "status": "error",
       "test_code": "{ \"hello\" } [ greet ] unit-test",
-      "message": "unimplemented"
+      "message": "practice-stub/practice-stub-tests.factor:5\nunimplemented"
     },
     {
       "name": "greet returns world",
       "status": "error",
       "test_code": "{ \"world\" } [ greet ] unit-test",
-      "message": "unimplemented"
+      "message": "practice-stub/practice-stub-tests.factor:10\nunimplemented"
     }
   ]
 }
diff --git a/tests/success/exercism-tools/exercism-tools.factor b/tests/success/exercism-tools/exercism-tools.factor
index 428c2d3..df5f692 100644
--- a/tests/success/exercism-tools/exercism-tools.factor
+++ b/tests/success/exercism-tools/exercism-tools.factor
@@ -1,6 +1,7 @@
 USING: accessors command-line continuations debugger io kernel
-       lexer namespaces sequences source-files.errors.debugger
-       system tools.test vocabs vocabs.loader ;
+       lexer namespaces prettyprint.config sequences
+       source-files.errors.debugger system tools.test vocabs
+       vocabs.loader ;
 IN: exercism-tools
 
 SYNTAX: STOP-HERE
@@ -9,19 +10,15 @@ SYNTAX: STOP-HERE
 SYNTAX: TASK:
     lexer get next-line ;
 
-! Label the test that follows with its description. The marker lets the
-! wrapper strip this line from captured output and attach it to the next
-! test as a name, rather than leaving it in the previous test's output.
+! Label the test that follows with its description.
 : description ( str -- )
     "###DESC### " write print ;
 
-! Print one failure block in a stable, parser-friendly form. Bracketed by
-! markers so a wrapper can split the stream reliably and avoid Factor's
-! noisy callstack output (which is interleaved with subsequent failures).
+! Print one failure block in a stable, parser-friendly form.
 :: print-failure ( failure -- )
     "###FAIL_BEGIN###" print
     failure error-location print
-    failure error>> [ error. ] [ 2drop ] recover
+    [ failure error>> [ error. ] [ 2drop ] recover ] without-limits
     "###FAIL_END###" print
     flush ;
 
@@ -29,6 +26,7 @@ SYNTAX: TASK:
     test-failures get [ print-failure ] each ;
 
 : run-exercism-tests ( -- )
+    vocab-roots [ "." prefix ] change-global
     command-line get first
     [ require ] [ test ] bi
     test-failures get empty?
diff --git a/tests/syntax-error/exercism-tools/exercism-tools.factor b/tests/syntax-error/exercism-tools/exercism-tools.factor
index 428c2d3..df5f692 100644
--- a/tests/syntax-error/exercism-tools/exercism-tools.factor
+++ b/tests/syntax-error/exercism-tools/exercism-tools.factor
@@ -1,6 +1,7 @@
 USING: accessors command-line continuations debugger io kernel
-       lexer namespaces sequences source-files.errors.debugger
-       system tools.test vocabs vocabs.loader ;
+       lexer namespaces prettyprint.config sequences
+       source-files.errors.debugger system tools.test vocabs
+       vocabs.loader ;
 IN: exercism-tools
 
 SYNTAX: STOP-HERE
@@ -9,19 +10,15 @@ SYNTAX: STOP-HERE
 SYNTAX: TASK:
     lexer get next-line ;
 
-! Label the test that follows with its description. The marker lets the
-! wrapper strip this line from captured output and attach it to the next
-! test as a name, rather than leaving it in the previous test's output.
+! Label the test that follows with its description.
 : description ( str -- )
     "###DESC### " write print ;
 
-! Print one failure block in a stable, parser-friendly form. Bracketed by
-! markers so a wrapper can split the stream reliably and avoid Factor's
-! noisy callstack output (which is interleaved with subsequent failures).
+! Print one failure block in a stable, parser-friendly form.
 :: print-failure ( failure -- )
     "###FAIL_BEGIN###" print
     failure error-location print
-    failure error>> [ error. ] [ 2drop ] recover
+    [ failure error>> [ error. ] [ 2drop ] recover ] without-limits
     "###FAIL_END###" print
     flush ;
 
@@ -29,6 +26,7 @@ SYNTAX: TASK:
     test-failures get [ print-failure ] each ;
 
 : run-exercism-tests ( -- )
+    vocab-roots [ "." prefix ] change-global
     command-line get first
     [ require ] [ test ] bi
     test-failures get empty?
diff --git a/tests/syntax-error/expected_results.json b/tests/syntax-error/expected_results.json
index 040ef79..7f0623f 100644
--- a/tests/syntax-error/expected_results.json
+++ b/tests/syntax-error/expected_results.json
@@ -1,5 +1,5 @@
 {
   "version": 3,
   "status": "error",
-  "message": "/opt/test-runner/tests/syntax-error/syntax-error/syntax-error.factor\n\n4: : greet ( -- str ) @#$% ;\n                          ^\nNo word named '@#$%' found in current vocabulary search path"
+  "message": "syntax-error/syntax-error.factor\n\n4: : greet ( -- str ) @#$% ;\n                          ^\nNo word named '@#$%' found in current vocabulary search path"
 }
diff --git a/tests/wishlist-vocabs/exercism-tools/exercism-tools.factor b/tests/wishlist-vocabs/exercism-tools/exercism-tools.factor
index 428c2d3..df5f692 100644
--- a/tests/wishlist-vocabs/exercism-tools/exercism-tools.factor
+++ b/tests/wishlist-vocabs/exercism-tools/exercism-tools.factor
@@ -1,6 +1,7 @@
 USING: accessors command-line continuations debugger io kernel
-       lexer namespaces sequences source-files.errors.debugger
-       system tools.test vocabs vocabs.loader ;
+       lexer namespaces prettyprint.config sequences
+       source-files.errors.debugger system tools.test vocabs
+       vocabs.loader ;
 IN: exercism-tools
 
 SYNTAX: STOP-HERE
@@ -9,19 +10,15 @@ SYNTAX: STOP-HERE
 SYNTAX: TASK:
     lexer get next-line ;
 
-! Label the test that follows with its description. The marker lets the
-! wrapper strip this line from captured output and attach it to the next
-! test as a name, rather than leaving it in the previous test's output.
+! Label the test that follows with its description.
 : description ( str -- )
     "###DESC### " write print ;
 
-! Print one failure block in a stable, parser-friendly form. Bracketed by
-! markers so a wrapper can split the stream reliably and avoid Factor's
-! noisy callstack output (which is interleaved with subsequent failures).
+! Print one failure block in a stable, parser-friendly form.
 :: print-failure ( failure -- )
     "###FAIL_BEGIN###" print
     failure error-location print
-    failure error>> [ error. ] [ 2drop ] recover
+    [ failure error>> [ error. ] [ 2drop ] recover ] without-limits
     "###FAIL_END###" print
     flush ;
 
@@ -29,6 +26,7 @@ SYNTAX: TASK:
     test-failures get [ print-failure ] each ;
 
 : run-exercism-tests ( -- )
+    vocab-roots [ "." prefix ] change-global
     command-line get first
     [ require ] [ test ] bi
     test-failures get empty?
diff --git a/tests/wishlist-vocabs/expected_results.json b/tests/wishlist-vocabs/expected_results.json
index 625540c..b579b5f 100644
--- a/tests/wishlist-vocabs/expected_results.json
+++ b/tests/wishlist-vocabs/expected_results.json
@@ -36,6 +36,11 @@
       "name": "pair-rocket builds an assoc",
       "status": "pass",
       "test_code": "{ H{ { \"ada\" 1 } { \"bob\" 2 } } } [ scores ] unit-test"
+    },
+    {
+      "name": "assoc-invert swaps keys and values",
+      "status": "pass",
+      "test_code": "{ H{ { 1 \"ada\" } { 2 \"bob\" } } } [ H{ { \"ada\" 1 } { \"bob\" 2 } } invert-assoc ] unit-test"
     }
   ]
 }
diff --git a/tests/wishlist-vocabs/wishlist-vocabs/wishlist-vocabs-tests.factor b/tests/wishlist-vocabs/wishlist-vocabs/wishlist-vocabs-tests.factor
index fa4fb54..69ad50a 100644
--- a/tests/wishlist-vocabs/wishlist-vocabs/wishlist-vocabs-tests.factor
+++ b/tests/wishlist-vocabs/wishlist-vocabs/wishlist-vocabs-tests.factor
@@ -21,3 +21,6 @@ IN: wishlist-vocabs.tests
 
 "pair-rocket builds an assoc" description
 { H{ { "ada" 1 } { "bob" 2 } } } [ scores ] unit-test
+
+"assoc-invert swaps keys and values" description
+{ H{ { 1 "ada" } { 2 "bob" } } } [ H{ { "ada" 1 } { "bob" 2 } } invert-assoc ] unit-test
diff --git a/tests/wishlist-vocabs/wishlist-vocabs/wishlist-vocabs.factor b/tests/wishlist-vocabs/wishlist-vocabs/wishlist-vocabs.factor
index 0abd2f8..3eff6ca 100644
--- a/tests/wishlist-vocabs/wishlist-vocabs/wishlist-vocabs.factor
+++ b/tests/wishlist-vocabs/wishlist-vocabs/wishlist-vocabs.factor
@@ -1,6 +1,6 @@
-USING: arrays circular hashtables infix interpolate kernel math
-       namespaces pair-rocket qw sequences sequences.extras
-       sequences.repeating ;
+USING: arrays assocs.extras circular hashtables infix interpolate
+       kernel math namespaces pair-rocket qw sequences
+       sequences.extras sequences.repeating ;
 IN: wishlist-vocabs
 
 ! qw{ ... } reads a whitespace-separated literal sequence of strings (qw).
@@ -25,3 +25,6 @@ INFIX:: add ( x y -- z ) x + y ;
 
 ! => pairs each key with the next value, building assoc literals (pair-rocket).
 : scores ( -- assoc ) { "ada" => 1 "bob" => 2 } >hashtable ;
+
+! assoc-invert swaps every key with its value (assocs.extras).
+: invert-assoc ( assoc -- newassoc ) assoc-invert ;