diff --git a/.github/workflows/build-windows.yml b/.github/workflows/build-windows.yml
index ed49a10f..e7082454 100644
--- a/.github/workflows/build-windows.yml
+++ b/.github/workflows/build-windows.yml
@@ -1243,6 +1243,36 @@ jobs:
 
           Compress-Archive -Path (Join-Path $outRoot '*') -DestinationPath (Join-Path $env:GITHUB_WORKSPACE 'nlpengine-compile-libs.zip') -Force
 
+      - name: Compiled analyzer calls interpreter-only builtins
+        shell: bash
+        run: |
+          set -eo pipefail
+          # A builtin added to the interpreter without a compiled Arun:: twin made
+          # every compiled analyzer that called it fail to build: 23 of them, among
+          # them jsonwrite, which the KB template calls. The generator now routes
+          # them through Arun::fnbridge. Build this fixture against the compile
+          # libraries just packaged, run it, and compare with the interpreted run.
+          FIX=.github/workflows/tests/compiled-bridge
+          LIBS="$(cygpath -m "$GITHUB_WORKSPACE")/compile-libs"
+          rm -rf "$FIX/logs" "$FIX/input/text.txt_log" "$FIX/output" "$FIX/run" "$FIX/build"
+          mkdir -p "$FIX/logs"
+          ./bin/Release/nlp.exe -ANA "$FIX" -WORK ./ "$FIX/input/text.txt"
+          tr -d '\r' < "$FIX/input/text.txt_log/output.txt" > bridge-interpreted.txt
+          n=$(wc -l < bridge-interpreted.txt)
+          if [ "$n" -ne 23 ]; then
+            echo "FAIL(compiled-bridge): interpreted run printed $n lines, wanted 23:"; cat bridge-interpreted.txt; exit 1
+          fi
+          rm -rf "$FIX/input/text.txt_log" "$FIX/output"
+          ./bin/Release/nlp.exe -COMPILEANA -ANA "$FIX" -WORK ./ "$FIX/input/text.txt"
+          cmake -S "$FIX" -B "$FIX/build" -A x64 -DENGINE_LIBS="$LIBS"
+          cmake --build "$FIX/build" --config Release
+          rm -rf "$FIX/input/text.txt_log" "$FIX/output"
+          ./bin/Release/nlp.exe -COMPILED -ANA "$FIX" -WORK ./ "$FIX/input/text.txt"
+          if ! diff bridge-interpreted.txt <(tr -d '\r' < "$FIX/input/text.txt_log/output.txt"); then
+            echo "FAIL(compiled-bridge): compiled output differs from interpreted"; exit 1
+          fi
+          echo "[compiled-bridge] interpreter-only builtins work in a compiled analyzer"
+
       - name: Upload nlpengine-compile-libs.zip
         uses: actions/upload-artifact@v4
         with:
diff --git a/.github/workflows/tests/compiled-bridge/.gitignore b/.github/workflows/tests/compiled-bridge/.gitignore
new file mode 100644
index 00000000..24088e45
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/.gitignore
@@ -0,0 +1,10 @@
+run/
+kb/
+build/
+logs/
+output/
+input/*_log/
+*.dll
+*.exp
+*.lib
+*.pdb
diff --git a/.github/workflows/tests/compiled-bridge/CMakeLists.txt b/.github/workflows/tests/compiled-bridge/CMakeLists.txt
new file mode 100644
index 00000000..c5ecee0a
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/CMakeLists.txt
@@ -0,0 +1,50 @@
+# Builds this fixture as a compiled analyzer (analyzer.dll) against the
+# packaged compile libraries, as the VS Code extension and the compile service
+# do (their generated CMakeLists.txt is the model). Used by the Windows CI step
+# "Compiled analyzer calls interpreter-only builtins".
+#
+#   nlp -COMPILEANA -ANA <this folder> ...     (writes run/*.cpp)
+#   cmake -S <this folder> -B <this folder>/build -A x64 -DENGINE_LIBS=<compile-libs>
+#   cmake --build <this folder>/build --config Release
+cmake_minimum_required(VERSION 3.16)
+project(nlp_generated_library LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+if(NOT ENGINE_LIBS)
+    message(FATAL_ERROR "Pass -DENGINE_LIBS=<unpacked nlpengine-compile-libs folder>.")
+endif()
+
+set(ANALYZER_DIR "${CMAKE_CURRENT_SOURCE_DIR}")
+set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${ANALYZER_DIR}")
+set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${ANALYZER_DIR}")
+set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${ANALYZER_DIR}")
+foreach(OUTPUTCONFIG ${CMAKE_CONFIGURATION_TYPES})
+    string(TOUPPER ${OUTPUTCONFIG} OUTPUTCONFIG_UPPER)
+    set(CMAKE_RUNTIME_OUTPUT_DIRECTORY_${OUTPUTCONFIG_UPPER} "${ANALYZER_DIR}")
+    set(CMAKE_LIBRARY_OUTPUT_DIRECTORY_${OUTPUTCONFIG_UPPER} "${ANALYZER_DIR}")
+    set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY_${OUTPUTCONFIG_UPPER} "${ANALYZER_DIR}")
+endforeach()
+
+file(GLOB GENERATED_CPP "${ANALYZER_DIR}/run/*.cpp" "${ANALYZER_DIR}/kb/*.cpp")
+if(NOT GENERATED_CPP)
+    message(FATAL_ERROR "No generated C++ in run/ or kb/. Run nlp -COMPILEANA first.")
+endif()
+
+add_library(nlp_generated SHARED ${GENERATED_CPP})
+set_target_properties(nlp_generated PROPERTIES OUTPUT_NAME "analyzer" PREFIX "")
+
+target_include_directories(nlp_generated PRIVATE
+    "${ANALYZER_DIR}"
+    "${ANALYZER_DIR}/run"
+    "${ANALYZER_DIR}/kb"
+    "${ENGINE_LIBS}/include/Api"
+    "${ENGINE_LIBS}/include/cs"
+    "${ENGINE_LIBS}/include"
+)
+
+file(GLOB ENGINE_LIBS_ALL "${ENGINE_LIBS}/lib/*.lib")
+target_link_libraries(nlp_generated PRIVATE ${ENGINE_LIBS_ALL})
+target_compile_definitions(nlp_generated PRIVATE _CRT_SECURE_NO_WARNINGS)
+target_compile_options(nlp_generated PRIVATE /wd4005 /FI"StdAfx.h" /MP)
diff --git a/.github/workflows/tests/compiled-bridge/StdAfx.h b/.github/workflows/tests/compiled-bridge/StdAfx.h
new file mode 100644
index 00000000..b1e5195d
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/StdAfx.h
@@ -0,0 +1,13 @@
+// Auto-generated stub. Engine-generated .cpp files include "StdAfx.h" by convention.
+#pragma once
+#ifdef _WIN32
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
+#ifndef NOMINMAX
+#define NOMINMAX
+#endif
+#include <windows.h>
+#include <tchar.h>
+#endif
+#include "my_tchar.h"
diff --git a/.github/workflows/tests/compiled-bridge/input/text.txt b/.github/workflows/tests/compiled-bridge/input/text.txt
new file mode 100644
index 00000000..3b18e512
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/input/text.txt
@@ -0,0 +1 @@
+hello world
diff --git a/.github/workflows/tests/compiled-bridge/spec/abs.nlp b/.github/workflows/tests/compiled-bridge/spec/abs.nlp
new file mode 100644
index 00000000..bdf65cd9
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/abs.nlp
@@ -0,0 +1,10 @@
+###############################################
+# FILE:     abs.nlp
+# SUBJ:     abs() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("r") = abs(-5);
+"output.txt" << "abs: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/analyzer.seq b/.github/workflows/tests/compiled-bridge/spec/analyzer.seq
new file mode 100644
index 00000000..c0c68f7a
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/analyzer.seq
@@ -0,0 +1,24 @@
+tokenize	nil	# 
+nlp	abs	# 
+nlp	arrayreverse	# 
+nlp	arrayslice	# 
+nlp	arraysort	# 
+nlp	arrayunique	# 
+nlp	push	# 
+nlp	strindexof	# 
+nlp	strlastindexof	# 
+nlp	striscaps	# 
+nlp	strjoin	# 
+nlp	rematch	# 
+nlp	refind	# 
+nlp	resubst	# 
+nlp	fileexists	# 
+nlp	direxists	# 
+nlp	filesize	# 
+nlp	readfile	# 
+nlp	readlines	# 
+nlp	dirlist	# 
+nlp	deletefile	# 
+nlp	randomint	# 
+nlp	jsonwrite	# 
+nlp	jsonparse	# 
diff --git a/.github/workflows/tests/compiled-bridge/spec/arrayreverse.nlp b/.github/workflows/tests/compiled-bridge/spec/arrayreverse.nlp
new file mode 100644
index 00000000..3ab4c454
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/arrayreverse.nlp
@@ -0,0 +1,12 @@
+###############################################
+# FILE:     arrayreverse.nlp
+# SUBJ:     arrayreverse() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("a")[0] = 1; L("a")[1] = 2; L("a")[2] = 3;
+L("b") = arrayreverse(L("a"));
+L("r") = str(L("b")[0]) + str(L("b")[1]) + str(L("b")[2]);
+"output.txt" << "arrayreverse: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/arrayslice.nlp b/.github/workflows/tests/compiled-bridge/spec/arrayslice.nlp
new file mode 100644
index 00000000..1fe031ae
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/arrayslice.nlp
@@ -0,0 +1,12 @@
+###############################################
+# FILE:     arrayslice.nlp
+# SUBJ:     arrayslice() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("a")[0] = "p"; L("a")[1] = "q"; L("a")[2] = "r";
+L("b") = arrayslice(L("a"), 1);
+L("r") = L("b")[0] + L("b")[1];
+"output.txt" << "arrayslice: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/arraysort.nlp b/.github/workflows/tests/compiled-bridge/spec/arraysort.nlp
new file mode 100644
index 00000000..86aff8f0
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/arraysort.nlp
@@ -0,0 +1,12 @@
+###############################################
+# FILE:     arraysort.nlp
+# SUBJ:     arraysort() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("a")[0] = 30; L("a")[1] = 10; L("a")[2] = 20;
+L("b") = arraysort(L("a"), 1);
+L("r") = str(L("b")[0]) + "," + str(L("b")[1]) + "," + str(L("b")[2]);
+"output.txt" << "arraysort: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/arrayunique.nlp b/.github/workflows/tests/compiled-bridge/spec/arrayunique.nlp
new file mode 100644
index 00000000..035e07fd
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/arrayunique.nlp
@@ -0,0 +1,12 @@
+###############################################
+# FILE:     arrayunique.nlp
+# SUBJ:     arrayunique() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("a")[0] = "x"; L("a")[1] = "x"; L("a")[2] = "y";
+L("b") = arrayunique(L("a"));
+L("r") = str(arraylength(L("b")));
+"output.txt" << "arrayunique: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/deletefile.nlp b/.github/workflows/tests/compiled-bridge/spec/deletefile.nlp
new file mode 100644
index 00000000..7ea30dd8
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/deletefile.nlp
@@ -0,0 +1,10 @@
+###############################################
+# FILE:     deletefile.nlp
+# SUBJ:     deletefile() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("r") = str(deletefile("no-such-file.txt"));
+"output.txt" << "deletefile: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/direxists.nlp b/.github/workflows/tests/compiled-bridge/spec/direxists.nlp
new file mode 100644
index 00000000..81151f3b
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/direxists.nlp
@@ -0,0 +1,10 @@
+###############################################
+# FILE:     direxists.nlp
+# SUBJ:     direxists() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("r") = str(direxists("no-such-dir"));
+"output.txt" << "direxists: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/dirlist.nlp b/.github/workflows/tests/compiled-bridge/spec/dirlist.nlp
new file mode 100644
index 00000000..71cd2a78
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/dirlist.nlp
@@ -0,0 +1,10 @@
+###############################################
+# FILE:     dirlist.nlp
+# SUBJ:     dirlist() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("r") = str(arraylength(dirlist("no-such-dir")));
+"output.txt" << "dirlist: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/fileexists.nlp b/.github/workflows/tests/compiled-bridge/spec/fileexists.nlp
new file mode 100644
index 00000000..fd9dc876
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/fileexists.nlp
@@ -0,0 +1,10 @@
+###############################################
+# FILE:     fileexists.nlp
+# SUBJ:     fileexists() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("r") = str(fileexists("no-such-file.txt"));
+"output.txt" << "fileexists: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/filesize.nlp b/.github/workflows/tests/compiled-bridge/spec/filesize.nlp
new file mode 100644
index 00000000..96a1a01b
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/filesize.nlp
@@ -0,0 +1,10 @@
+###############################################
+# FILE:     filesize.nlp
+# SUBJ:     filesize() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("r") = filesize("no-such-file.txt");
+"output.txt" << "filesize: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/jsonparse.nlp b/.github/workflows/tests/compiled-bridge/spec/jsonparse.nlp
new file mode 100644
index 00000000..508c62d4
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/jsonparse.nlp
@@ -0,0 +1,12 @@
+###############################################
+# FILE:     jsonparse.nlp
+# SUBJ:     jsonparse() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("c") = makeconcept(findroot(), "jp");
+L("ok") = jsonparse("{\"a\": 1}", L("c"));
+L("r") = str(L("ok")) + " " + str(numval(L("c"), "a"));
+"output.txt" << "jsonparse: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/jsonwrite.nlp b/.github/workflows/tests/compiled-bridge/spec/jsonwrite.nlp
new file mode 100644
index 00000000..1be4ce66
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/jsonwrite.nlp
@@ -0,0 +1,14 @@
+###############################################
+# FILE:     jsonwrite.nlp
+# SUBJ:     jsonwrite() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("c") = makeconcept(findroot(), "jw");
+addstrval(L("c"), "k", "v");
+L("f") = G("$apppath") + "/output/bridge.json";
+jsonwrite(L("f"), L("c"));
+L("r") = str(fileexists(L("f"))) + " " + str(strlength(readfile(L("f"))) > 10);
+"output.txt" << "jsonwrite: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/push.nlp b/.github/workflows/tests/compiled-bridge/spec/push.nlp
new file mode 100644
index 00000000..ad472baf
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/push.nlp
@@ -0,0 +1,12 @@
+###############################################
+# FILE:     push.nlp
+# SUBJ:     push() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("a")[0] = 2; L("a")[1] = 3;
+L("b") = push(1, L("a"));
+L("r") = str(L("b")[0]) + str(L("b")[1]) + str(L("b")[2]);
+"output.txt" << "push: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/randomint.nlp b/.github/workflows/tests/compiled-bridge/spec/randomint.nlp
new file mode 100644
index 00000000..384e68fb
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/randomint.nlp
@@ -0,0 +1,11 @@
+###############################################
+# FILE:     randomint.nlp
+# SUBJ:     randomint() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("n") = randomint(5, 5);
+L("r") = L("n");
+"output.txt" << "randomint: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/readfile.nlp b/.github/workflows/tests/compiled-bridge/spec/readfile.nlp
new file mode 100644
index 00000000..8c6d4181
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/readfile.nlp
@@ -0,0 +1,10 @@
+###############################################
+# FILE:     readfile.nlp
+# SUBJ:     readfile() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("r") = "[" + readfile("no-such-file.txt") + "]";
+"output.txt" << "readfile: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/readlines.nlp b/.github/workflows/tests/compiled-bridge/spec/readlines.nlp
new file mode 100644
index 00000000..92d41203
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/readlines.nlp
@@ -0,0 +1,10 @@
+###############################################
+# FILE:     readlines.nlp
+# SUBJ:     readlines() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("r") = str(arraylength(readlines("no-such-file.txt")));
+"output.txt" << "readlines: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/refind.nlp b/.github/workflows/tests/compiled-bridge/spec/refind.nlp
new file mode 100644
index 00000000..3e9272a2
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/refind.nlp
@@ -0,0 +1,10 @@
+###############################################
+# FILE:     refind.nlp
+# SUBJ:     refind() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("r") = refind("abcabc", "c");
+"output.txt" << "refind: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/rematch.nlp b/.github/workflows/tests/compiled-bridge/spec/rematch.nlp
new file mode 100644
index 00000000..2942009f
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/rematch.nlp
@@ -0,0 +1,10 @@
+###############################################
+# FILE:     rematch.nlp
+# SUBJ:     rematch() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("r") = str(rematch("abc", "a.c")) + str(rematch("abc", "x"));
+"output.txt" << "rematch: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/resubst.nlp b/.github/workflows/tests/compiled-bridge/spec/resubst.nlp
new file mode 100644
index 00000000..4f6d2d23
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/resubst.nlp
@@ -0,0 +1,10 @@
+###############################################
+# FILE:     resubst.nlp
+# SUBJ:     resubst() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("r") = resubst("abcabc", "b", "X");
+"output.txt" << "resubst: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/strindexof.nlp b/.github/workflows/tests/compiled-bridge/spec/strindexof.nlp
new file mode 100644
index 00000000..df4dc057
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/strindexof.nlp
@@ -0,0 +1,10 @@
+###############################################
+# FILE:     strindexof.nlp
+# SUBJ:     strindexof() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("r") = strindexof("hello", "l");
+"output.txt" << "strindexof: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/striscaps.nlp b/.github/workflows/tests/compiled-bridge/spec/striscaps.nlp
new file mode 100644
index 00000000..daa9a5ed
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/striscaps.nlp
@@ -0,0 +1,10 @@
+###############################################
+# FILE:     striscaps.nlp
+# SUBJ:     striscaps() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("r") = str(striscaps("Hello")) + str(striscaps("hello"));
+"output.txt" << "striscaps: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/strjoin.nlp b/.github/workflows/tests/compiled-bridge/spec/strjoin.nlp
new file mode 100644
index 00000000..8b18b897
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/strjoin.nlp
@@ -0,0 +1,11 @@
+###############################################
+# FILE:     strjoin.nlp
+# SUBJ:     strjoin() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("a")[0] = "x"; L("a")[1] = "y"; L("a")[2] = "z";
+L("r") = strjoin(L("a"), "-");
+"output.txt" << "strjoin: " << L("r") << "\n";
+@@CODE
diff --git a/.github/workflows/tests/compiled-bridge/spec/strlastindexof.nlp b/.github/workflows/tests/compiled-bridge/spec/strlastindexof.nlp
new file mode 100644
index 00000000..450da5de
--- /dev/null
+++ b/.github/workflows/tests/compiled-bridge/spec/strlastindexof.nlp
@@ -0,0 +1,10 @@
+###############################################
+# FILE:     strlastindexof.nlp
+# SUBJ:     strlastindexof() in interpreted and compiled analyzers. A compiled
+#           analyzer calls it through Arun::fnbridge.
+###############################################
+
+@CODE
+L("r") = strlastindexof("hello", "l");
+"output.txt" << "strlastindexof: " << L("r") << "\n";
+@@CODE
diff --git a/include/Api/lite/Arun.h b/include/Api/lite/Arun.h
index e89bdd38..ac2f4704 100644
--- a/include/Api/lite/Arun.h
+++ b/include/Api/lite/Arun.h
@@ -15,6 +15,7 @@ All rights reserved.
 
 #include <iostream>
 #include <assert.h>
+#include <initializer_list>
 #include "lite.h"
 
 typedef void DELTS;              // Doubly-linked list.  // 07/07/03 AM.
@@ -1269,6 +1270,8 @@ class LITE_API Arun
 	static RFASem *sem(float);												// 03/07/02 AM.
 	static RFASem *sem(_TCHAR*);												// 03/07/02 AM.
 	static RFASem *sem(RFASem*);	// Noop.								// 03/07/02 AM.
+	// Builtins with no compiled twin run through the interpreter (arunbridge.cpp).
+	static RFASem *fnbridge(Nlppp *, _TCHAR *name, std::initializer_list<RFASem *> args);
 
 	static _TCHAR *strtotitle(Nlppp*,_TCHAR*);								// 08/22/00 AM.
 	static _TCHAR *strtotitle(Nlppp*,RFASem*);							// 08/22/00 AM.
diff --git a/lite/arunbridge.cpp b/lite/arunbridge.cpp
new file mode 100644
index 00000000..e7ed8d7d
--- /dev/null
+++ b/lite/arunbridge.cpp
@@ -0,0 +1,82 @@
+/*******************************************************************************
+Copyright (c) 2026 by VisualText.
+All rights reserved.
+********************************************************************************
+*
+* NAME:	ARUNBRIDGE.CPP
+* FILE:	lite/arunbridge.cpp
+* SUBJ:	Compiled-analyzer bridge to builtins that exist only in the
+*			interpreter.
+* NOTE:	The code generator writes a call to a builtin as Arun::<name>(...),
+*			so a builtin added to Fn:: without a compiled Arun:: twin made any
+*			compiled analyzer that called it fail to build. For those builtins
+*			the generator now writes Arun::fnbridge(nlppp, "name", {args}),
+*			which runs the interpreter's own implementation: compiled and
+*			interpreted behave the same, and nothing is reimplemented.
+*
+*******************************************************************************/
+
+#include "StdAfx.h"
+#include "machine.h"
+#include "u_out.h"
+#include "lite/global.h"
+#include "inline.h"
+#include "dlist.h"
+#include "node.h"
+#include "lite/iarg.h"
+#include "str.h"
+#include "io.h"
+#include "tree.h"
+#include "lite/nlppp.h"
+#include "gen.h"
+#include "parse.h"
+#include "iaction.h"
+#include "rfasem.h"
+#include "fn.h"
+#include "lite/Arun.h"
+
+
+/********************************************
+* FN:		FNBRIDGE
+* SUBJ:	Call the interpreter's builtin NAME with already-evaluated ARGS.
+* RET:	The builtin's value (never 0: an error yields 0 as a number).
+* NOTE:	Mirrors Iaction::eval: the arguments become IASEM args of a
+*			temporary action, Fn::fnCall runs the builtin, and the argument
+*			list is freed with Iarg::delete_top, as Iaction::eval frees its
+*			evaluated arguments. The bridge owns ARGS, as an Arun:: builtin
+*			owns the RFASem* args the generated code hands it.
+********************************************/
+
+RFASem *Arun::fnbridge(
+	Nlppp *nlppp,
+	_TCHAR *name,
+	std::initializer_list<RFASem *> args
+	)
+{
+Dlist<Iarg> *iargs = new Dlist<Iarg>();
+for (RFASem *sem : args)
+	iargs->rpush(new Iarg(sem ? sem : new RFASem(0LL)));
+
+Iaction action(name, iargs, 0);
+bool badname = false;
+RFASem *val = 0;
+bool ok = Fn::fnCall(&action, nlppp, /*UP*/ badname, val);
+action.setArgs(0);					// The action doesn't own the list.
+Iarg::delete_top(iargs);
+
+if (!ok && val)
+	{
+	delete val;
+	val = 0;
+	}
+if (!ok)
+	{
+	std::_t_strstream gerrStr;
+	if (badname)
+		gerrStr << _T("[Fncall: Error: Unknown fn/action name=") << name << _T("]") << std::ends;
+	else
+		gerrStr << _T("[Fncall: Error executing fn/action=") << name << _T("]") << std::ends;
+	nlppp->parse_->errOut(&gerrStr,false);
+	}
+return val ? val : new RFASem(0LL);
+}
diff --git a/lite/iaction.cpp b/lite/iaction.cpp
index 3a6c633a..8c9b8eac 100644
--- a/lite/iaction.cpp
+++ b/lite/iaction.cpp
@@ -795,6 +795,47 @@ return true;
 }
 
 
+// Builtins that exist only in the interpreter (Fn::), with no compiled
+// Arun:: twin. A compiled analyzer calls them through Arun::fnbridge,
+// which runs the interpreter's implementation. Before, the generated
+// Arun::<name>(...) call didn't compile. A new builtin without an Arun::
+// function belongs here.
+static const _TCHAR *bridgedFns[] = {
+	_T("abs"),
+	_T("arrayreverse"),
+	_T("arrayslice"),
+	_T("arraysort"),
+	_T("arrayunique"),
+	_T("deletefile"),
+	_T("direxists"),
+	_T("dirlist"),
+	_T("fileexists"),
+	_T("filesize"),
+	_T("jsonparse"),
+	_T("jsonwrite"),
+	_T("push"),
+	_T("randomint"),
+	_T("readfile"),
+	_T("readlines"),
+	_T("refind"),
+	_T("rematch"),
+	_T("resubst"),
+	_T("strindexof"),
+	_T("striscaps"),
+	_T("strjoin"),
+	_T("strlastindexof"),
+	0
+	};
+
+static bool isBridged(const _TCHAR *name)
+{
+for (const _TCHAR **p = bridgedFns; *p; ++p)
+	if (!strcmp_i((_TCHAR *) *p, (_TCHAR *) name))
+		return true;
+return false;
+}
+
+
 /********************************************
 * FN:		GENEVAL
 * CR:		05/07/00 AM.
@@ -940,10 +981,13 @@ else
 _TCHAR callPrefix[MAXSTR + 64];
 callPrefix[0] = '\0';
 bool userdef = false;	// User-defined in NLP++					// 03/11/02 AM.
+bool bridged = false;	// Interpreter-only builtin, via Arun::fnbridge.
 if (!scope_ || !*scope_)													// 02/13/01 AM.
 	{
 //	if (VTRun_Ptr->isBuiltin(fnname))	// 08/28/02 AM.	// [DEGLOB]	// 10/15/20 AM.
-	if (vtrun->isBuiltin(fnname))						// [DEGLOB]	// 10/15/20 AM.
+	if (vtrun->isBuiltin(fnname) && isBridged(fnname))
+		bridged = true;		// No Arun:: twin: Arun::fnbridge.
+	else if (vtrun->isBuiltin(fnname))						// [DEGLOB]	// 10/15/20 AM.
 		_stprintf(callPrefix, _T("Arun::%s"), fnname);
 	else																			// 12/24/01 AM.
 		{
@@ -1056,24 +1100,39 @@ if (wrapLambda)
 	for (Delt<Iarg> *d = args_->getFirst(); d; d = d->Right(), ++idx)
 		{
 		*fcode << _T("auto _a") << idx << _T(" = ");
-		if (userdef) *fcode << _T("Arun::sem(");
+		if (userdef || bridged) *fcode << _T("Arun::sem(");
 		if (!emitArgExpr(d->getData())) return false;
-		if (userdef) *fcode << _T(")");
+		if (userdef || bridged) *fcode << _T(")");
 		*fcode << _T("; ");
 		}
+	if (bridged)
+		{
+		*fcode << _T("return Arun::fnbridge(") << firstArg
+				 << _T(", (_TCHAR*)_T(\"") << fnname << _T("\"), {");
+		for (int i = 0; i < argCount; ++i)
+			*fcode << (i ? _T(", _a") : _T("_a")) << i;
+		*fcode << _T("}); }())");
+		}
+	else
+		{
 	*fcode << _T("return ") << callPrefix << _T("(") << firstArg;
 	for (int i = 0; i < argCount; ++i)
 		*fcode << _T(", _a") << i;
 	*fcode << _T("); }())");
+		}
 	}
 else
 	{
 	// Legacy inline path: preserved for 0/1-arg calls and for calls that
 	// contain IAREF or IAOSTREAM args (the latter intentionally early-
 	// returns from Iaction::genEval — that quirk lives here).
+	if (bridged)
+		*fcode << _T("Arun::fnbridge(") << firstArg
+				 << _T(", (_TCHAR*)_T(\"") << fnname << _T("\"), {");
+	else
 	*fcode << callPrefix << _T("(") << firstArg;
 	Delt<Iarg> *darg = args_ ? args_->getFirst() : 0;
-	if (darg) *fcode << _T(", ");
+	if (darg && !bridged) *fcode << _T(", ");
 	for (; darg; darg = darg->Right())
 		{
 		Iarg *iarg = darg->getData();
@@ -1083,12 +1142,14 @@ else
 				return true;
 			return false;
 			}
-		if (userdef) *fcode << _T("Arun::sem(");
+		if (userdef || bridged) *fcode << _T("Arun::sem(");
 		if (!emitArgExpr(iarg)) return false;
-		if (userdef) *fcode << _T(")");
+		if (userdef || bridged) *fcode << _T(")");
 		if (darg->Right())
 			*fcode << _T(", ");
 		}
+	if (bridged)
+		*fcode << _T("}");
 	*fcode << _T(")");
 	}
 
diff --git a/nlp/main.cpp b/nlp/main.cpp
index 8717f9a4..0b015e40 100644
--- a/nlp/main.cpp
+++ b/nlp/main.cpp
@@ -15,7 +15,7 @@ All rights reserved.
 #include "lite/nlp_engine.h"
 #include "version.h"
 
-#define NLP_ENGINE_VERSION "4.2.24"
+#define NLP_ENGINE_VERSION "4.2.25"
 
 bool cmdReadArgs(int, _TCHAR *argv[], _TCHAR *&, _TCHAR *&, _TCHAR *&, _TCHAR *&, bool &, bool &, bool &, bool &, bool &, bool &, int &, bool &);
 void cmdHelpargs(_TCHAR *);