diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 8b41753..957dd1a 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -15,7 +15,7 @@ on:
   workflow_dispatch:
 
 permissions:
-  contents: write
+  contents: read
 
 jobs:
   build:
@@ -51,6 +51,8 @@ jobs:
     needs: build
     if: startsWith(github.ref, 'refs/tags/')
     runs-on: ubuntu-latest
+    permissions:
+      contents: write
 
     steps:
       - name: Download Artifacts
diff --git a/Makefile b/Makefile
index 375506a..78ce2e4 100644
--- a/Makefile
+++ b/Makefile
@@ -2,13 +2,17 @@
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 TOOLS		= host-run host-multiview host-shell host-path host-reveal host-notify host-edit host-clip host-info
-TESTS		= tests/test_host_edit_command.out
-COMMON_HEADERS	= src/host_common.h src/host_path.h src/host_capture.h src/host_edit_command.h src/uae_pragmas.h
+TESTS		= tests/test_host_common.out tests/test_host_command_builders.out tests/test_host_edit_command.out
+COMMON_HEADERS	= src/host_common.h src/host_path.h src/host_capture.h src/host_clip_command.h src/host_edit_command.h src/host_notify_command.h src/host_reveal_command.h src/uae_pragmas.h
 PACKAGE		= Host-Tools-$(VERSION).lha
 
+.PHONY: all test debug package clean
+
 all: $(TOOLS)
 test: $(TESTS)
-	./$(TESTS)
+	@for test in $(TESTS); do \
+		./$$test || exit $$?; \
+	done
 
 VERSION		= 2.3
 DATE		= 2026-04-30
@@ -21,7 +25,7 @@ CFLAGS		= -mcpu=68020 -noixemul -Os -fomit-frame-pointer -std=c99 -Wall -Wextra
 VERFLAGS	= -DVERSION_STR="\"$(VERSION)\"" -DDATE_STR="\"$(DATE)\""
 HOST_CC		?= $(shell command -v x86_64-linux-gnu-gcc 2>/dev/null || command -v cc 2>/dev/null || printf cc)
 HOST_NATIVE_FLAGS = $(if $(findstring x86_64-linux-gnu-gcc,$(notdir $(HOST_CC))),-B/usr/bin/x86_64-linux-gnu- -fuse-ld=bfd,)
-HOST_CFLAGS	= -std=c99 -Wall -Wextra -Isrc
+HOST_CFLAGS	= -std=c99 -Wall -Wextra -Wstrict-prototypes -Isrc
 
 host-run: src/host-run.c $(COMMON_HEADERS)
 	$(CC) $(CFLAGS) $(VERFLAGS) $(INCLUDES) src/host-run.c -o $@
@@ -50,6 +54,12 @@ host-clip: src/host-clip.c $(COMMON_HEADERS)
 host-info: src/host-info.c $(COMMON_HEADERS)
 	$(CC) $(CFLAGS) $(VERFLAGS) $(INCLUDES) src/host-info.c -o $@
 
+tests/test_host_common.out: tests/test_host_common.c src/host_common.h
+	$(HOST_CC) $(HOST_NATIVE_FLAGS) $(HOST_CFLAGS) tests/test_host_common.c -o $@
+
+tests/test_host_command_builders.out: tests/test_host_command_builders.c src/host_clip_command.h src/host_common.h src/host_notify_command.h src/host_reveal_command.h
+	$(HOST_CC) $(HOST_NATIVE_FLAGS) $(HOST_CFLAGS) tests/test_host_command_builders.c -o $@
+
 tests/test_host_edit_command.out: tests/test_host_edit_command.c src/host_edit_command.h src/host_common.h
 	$(HOST_CC) $(HOST_NATIVE_FLAGS) $(HOST_CFLAGS) tests/test_host_edit_command.c -o $@
 
diff --git a/src/host-clip.c b/src/host-clip.c
index ef27f40..7543aa7 100644
--- a/src/host-clip.c
+++ b/src/host-clip.c
@@ -6,6 +6,7 @@
 #include <stdio.h>
 #include <string.h>
 #include "host_capture.h"
+#include "host_clip_command.h"
 
 static const char version[] = "$VER: Host-Clip v" VERSION_STR " (" DATE_STR ")";
 
@@ -17,27 +18,12 @@ int print_usage()
     return 0;
 }
 
-static int append_copy_command(char *command, size_t command_size, const char *text)
-{
-    return host_append_literal(command, command_size, "printf %s ") &&
-           host_append_shell_arg(command, command_size, text, 0) &&
-           host_append_literal(command, command_size,
-                               " | if command -v pbcopy >/dev/null 2>&1; then pbcopy; elif command -v wl-copy >/dev/null 2>&1; then wl-copy; elif command -v xclip >/dev/null 2>&1; then xclip -selection clipboard; elif command -v xsel >/dev/null 2>&1; then xsel --clipboard --input; else printf 'No host clipboard backend found\\n' >&2; exit 127; fi");
-}
-
 int main(int argc, char *argv[])
 {
     static char command[HOST_MAX_COMMAND_LEN];
     static char text[2048];
     int start = 1;
 
-    static const char paste_command[] =
-        "if command -v pbpaste >/dev/null 2>&1; then pbpaste; "
-        "elif command -v wl-paste >/dev/null 2>&1; then wl-paste -n; "
-        "elif command -v xclip >/dev/null 2>&1; then xclip -selection clipboard -o; "
-        "elif command -v xsel >/dev/null 2>&1; then xsel --clipboard --output; "
-        "else printf 'No host clipboard backend found\\n' >&2; exit 127; fi";
-
     command[0] = '\0';
     text[0] = '\0';
 
@@ -63,7 +49,7 @@ int main(int argc, char *argv[])
             printf("Unexpected argument after paste\n");
             return print_usage();
         }
-        return host_print_command_output(paste_command);
+        return host_print_command_output(HOST_CLIP_PASTE_COMMAND);
     }
 
     if (strcmp(argv[1], "copy") == 0 || strcmp(argv[1], "-c") == 0) {
@@ -80,7 +66,7 @@ int main(int argc, char *argv[])
         return HOST_RETURN_ERROR;
     }
 
-    if (!append_copy_command(command, sizeof(command), text)) {
+    if (!host_append_clip_copy_command(command, sizeof(command), text)) {
         printf("Command is too long\n");
         return HOST_RETURN_ERROR;
     }
diff --git a/src/host-notify.c b/src/host-notify.c
index bc69a86..8127eda 100644
--- a/src/host-notify.c
+++ b/src/host-notify.c
@@ -6,6 +6,7 @@
 #include <stdio.h>
 #include <string.h>
 #include "host_capture.h"
+#include "host_notify_command.h"
 
 static const char version[] = "$VER: Host-Notify v" VERSION_STR " (" DATE_STR ")";
 
@@ -17,21 +18,6 @@ int print_usage()
     return 0;
 }
 
-static int append_notify_command(char *command, size_t command_size,
-                                 const char *title, const char *message)
-{
-    return host_append_literal(command, command_size,
-                              "if command -v notify-send >/dev/null 2>&1; then notify-send ") &&
-           host_append_shell_arg(command, command_size, title, 0) &&
-           host_append_shell_arg(command, command_size, message, 1) &&
-           host_append_literal(command, command_size,
-                               "; elif command -v osascript >/dev/null 2>&1; then osascript -e 'on run argv' -e 'display notification (item 2 of argv) with title (item 1 of argv)' -e 'end run' ") &&
-           host_append_shell_arg(command, command_size, title, 0) &&
-           host_append_shell_arg(command, command_size, message, 1) &&
-           host_append_literal(command, command_size,
-                               "; else exit 127; fi");
-}
-
 int main(int argc, char *argv[])
 {
     static char command[HOST_MAX_COMMAND_LEN];
@@ -39,7 +25,8 @@ int main(int argc, char *argv[])
     static char message[2048];
 
     command[0] = '\0';
-    strcpy(title, "Amiga");
+    title[0] = '\0';
+    host_append_literal(title, sizeof(title), "Amiga");
     message[0] = '\0';
 
     if (!InitUAEResource())
@@ -77,7 +64,7 @@ int main(int argc, char *argv[])
         }
     }
 
-    if (!append_notify_command(command, sizeof(command), title, message)) {
+    if (!host_append_notify_command(command, sizeof(command), title, message)) {
         printf("Command is too long\n");
         return HOST_RETURN_ERROR;
     }
diff --git a/src/host-reveal.c b/src/host-reveal.c
index 3ade285..ecf27ff 100644
--- a/src/host-reveal.c
+++ b/src/host-reveal.c
@@ -7,6 +7,7 @@
 #include <string.h>
 #include "host_capture.h"
 #include "host_path.h"
+#include "host_reveal_command.h"
 
 static const char version[] = "$VER: Host-Reveal v" VERSION_STR " (" DATE_STR ")";
 
@@ -18,18 +19,6 @@ int print_usage()
     return 0;
 }
 
-static int append_reveal_command(char *command, size_t command_size, const char *path)
-{
-    return host_append_literal(command, command_size,
-                              "if [ \"$(uname -s)\" = Darwin ] && command -v open >/dev/null 2>&1; then open -R ") &&
-           host_append_shell_arg(command, command_size, path, 0) &&
-           host_append_literal(command, command_size,
-                               "; elif command -v xdg-open >/dev/null 2>&1; then xdg-open \"$(dirname -- ") &&
-           host_append_shell_arg(command, command_size, path, 0) &&
-           host_append_literal(command, command_size,
-                               ")\"; else exit 127; fi");
-}
-
 int main(int argc, char *argv[])
 {
     static char filename[HOST_MAX_PATH_LEN];
@@ -78,7 +67,7 @@ int main(int argc, char *argv[])
             continue;
         }
 
-        if (!append_reveal_command(command, sizeof(command), target)) {
+        if (!host_append_reveal_command(command, sizeof(command), target)) {
             printf("Command is too long\n");
             status = HOST_RETURN_ERROR;
             continue;
diff --git a/src/host_clip_command.h b/src/host_clip_command.h
new file mode 100644
index 0000000..64738ec
--- /dev/null
+++ b/src/host_clip_command.h
@@ -0,0 +1,28 @@
+/*
+ * SPDX-FileCopyrightText: 2020-2026 Dimitris Panokostas
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#ifndef HOST_CLIP_COMMAND_H
+#define HOST_CLIP_COMMAND_H
+
+#include <stddef.h>
+#include "host_common.h"
+
+#define HOST_CLIP_PASTE_COMMAND \
+    "if command -v pbpaste >/dev/null 2>&1; then pbpaste; " \
+    "elif command -v wl-paste >/dev/null 2>&1; then wl-paste -n; " \
+    "elif command -v xclip >/dev/null 2>&1; then xclip -selection clipboard -o; " \
+    "elif command -v xsel >/dev/null 2>&1; then xsel --clipboard --output; " \
+    "else printf 'No host clipboard backend found\\n' >&2; exit 127; fi"
+
+static inline int host_append_clip_copy_command(char *command, size_t command_size,
+                                                const char *text)
+{
+    return host_append_literal(command, command_size, "printf %s ") &&
+           host_append_shell_arg(command, command_size, text, 0) &&
+           host_append_literal(command, command_size,
+                               " | if command -v pbcopy >/dev/null 2>&1; then pbcopy; elif command -v wl-copy >/dev/null 2>&1; then wl-copy; elif command -v xclip >/dev/null 2>&1; then xclip -selection clipboard; elif command -v xsel >/dev/null 2>&1; then xsel --clipboard --input; else printf 'No host clipboard backend found\\n' >&2; exit 127; fi");
+}
+
+#endif
diff --git a/src/host_notify_command.h b/src/host_notify_command.h
new file mode 100644
index 0000000..b68c9da
--- /dev/null
+++ b/src/host_notify_command.h
@@ -0,0 +1,27 @@
+/*
+ * SPDX-FileCopyrightText: 2020-2026 Dimitris Panokostas
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#ifndef HOST_NOTIFY_COMMAND_H
+#define HOST_NOTIFY_COMMAND_H
+
+#include <stddef.h>
+#include "host_common.h"
+
+static inline int host_append_notify_command(char *command, size_t command_size,
+                                             const char *title, const char *message)
+{
+    return host_append_literal(command, command_size,
+                              "if command -v notify-send >/dev/null 2>&1; then notify-send ") &&
+           host_append_shell_arg(command, command_size, title, 0) &&
+           host_append_shell_arg(command, command_size, message, 1) &&
+           host_append_literal(command, command_size,
+                               "; elif command -v osascript >/dev/null 2>&1; then osascript -e 'on run argv' -e 'display notification (item 2 of argv) with title (item 1 of argv)' -e 'end run' ") &&
+           host_append_shell_arg(command, command_size, title, 0) &&
+           host_append_shell_arg(command, command_size, message, 1) &&
+           host_append_literal(command, command_size,
+                               "; else exit 127; fi");
+}
+
+#endif
diff --git a/src/host_reveal_command.h b/src/host_reveal_command.h
new file mode 100644
index 0000000..542e81f
--- /dev/null
+++ b/src/host_reveal_command.h
@@ -0,0 +1,25 @@
+/*
+ * SPDX-FileCopyrightText: 2020-2026 Dimitris Panokostas
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#ifndef HOST_REVEAL_COMMAND_H
+#define HOST_REVEAL_COMMAND_H
+
+#include <stddef.h>
+#include "host_common.h"
+
+static inline int host_append_reveal_command(char *command, size_t command_size,
+                                             const char *path)
+{
+    return host_append_literal(command, command_size,
+                              "if [ \"$(uname -s)\" = Darwin ] && command -v open >/dev/null 2>&1; then open -R ") &&
+           host_append_shell_arg(command, command_size, path, 0) &&
+           host_append_literal(command, command_size,
+                               "; elif command -v xdg-open >/dev/null 2>&1; then xdg-open \"$(dirname -- ") &&
+           host_append_shell_arg(command, command_size, path, 0) &&
+           host_append_literal(command, command_size,
+                               ")\"; else exit 127; fi");
+}
+
+#endif
diff --git a/tests/test_host_command_builders.c b/tests/test_host_command_builders.c
new file mode 100644
index 0000000..36edc65
--- /dev/null
+++ b/tests/test_host_command_builders.c
@@ -0,0 +1,122 @@
+/*
+ * SPDX-FileCopyrightText: 2020-2026 Dimitris Panokostas
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "host_clip_command.h"
+#include "host_notify_command.h"
+#include "host_reveal_command.h"
+
+static void require(int condition, const char *message)
+{
+    if (!condition) {
+        fprintf(stderr, "%s\n", message);
+        exit(1);
+    }
+}
+
+static void require_contains(const char *value, const char *needle)
+{
+    if (strstr(value, needle) == NULL) {
+        fprintf(stderr, "missing substring: %s\n", needle);
+        fprintf(stderr, "value: %s\n", value);
+        exit(1);
+    }
+}
+
+static void require_shell_syntax(const char *command)
+{
+    char syntax_command[HOST_MAX_COMMAND_LEN * 2];
+
+    syntax_command[0] = '\0';
+    require(host_append_literal(syntax_command, sizeof(syntax_command), "sh -n -c "),
+            "syntax command prefix should fit");
+    require(host_append_shell_arg(syntax_command, sizeof(syntax_command), command, 0),
+            "syntax command should fit");
+    require(system(syntax_command) == 0, "generated shell command should parse");
+}
+
+static void test_reveal_command(void)
+{
+    char command[HOST_MAX_COMMAND_LEN];
+
+    command[0] = '\0';
+    require(host_append_reveal_command(command, sizeof(command), "/tmp/a b's.txt"),
+            "reveal command should build");
+
+    require_contains(command, "open -R '/tmp/a b'\\''s.txt'");
+    require_contains(command, "xdg-open \"$(dirname -- '/tmp/a b'\\''s.txt')\"");
+    require_contains(command, "else exit 127; fi");
+    require_shell_syntax(command);
+}
+
+static void test_notify_command(void)
+{
+    char command[HOST_MAX_COMMAND_LEN];
+
+    command[0] = '\0';
+    require(host_append_notify_command(command, sizeof(command),
+                                       "Build's Done", "Hello $USER & goodbye"),
+            "notify command should build");
+
+    require_contains(command, "notify-send 'Build'\\''s Done' 'Hello $USER & goodbye'");
+    require_contains(command, "osascript -e 'on run argv'");
+    require_contains(command, "'Build'\\''s Done' 'Hello $USER & goodbye'; else exit 127; fi");
+    require_shell_syntax(command);
+}
+
+static void test_clip_copy_command(void)
+{
+    char command[HOST_MAX_COMMAND_LEN];
+
+    command[0] = '\0';
+    require(host_append_clip_copy_command(command, sizeof(command),
+                                          "copy $HOME and 'quotes'"),
+            "clipboard copy command should build");
+
+    require_contains(command, "printf %s 'copy $HOME and '\\''quotes'\\''' |");
+    require_contains(command, "pbcopy");
+    require_contains(command, "wl-copy");
+    require_contains(command, "xclip -selection clipboard");
+    require_contains(command, "xsel --clipboard --input");
+    require_shell_syntax(command);
+}
+
+static void test_clip_paste_command(void)
+{
+    require_contains(HOST_CLIP_PASTE_COMMAND, "pbpaste");
+    require_contains(HOST_CLIP_PASTE_COMMAND, "wl-paste -n");
+    require_contains(HOST_CLIP_PASTE_COMMAND, "xclip -selection clipboard -o");
+    require_contains(HOST_CLIP_PASTE_COMMAND, "xsel --clipboard --output");
+    require_shell_syntax(HOST_CLIP_PASTE_COMMAND);
+}
+
+static void test_small_buffer_failures(void)
+{
+    char command[32];
+
+    command[0] = '\0';
+    require(!host_append_reveal_command(command, sizeof(command), "/tmp/a.txt"),
+            "small reveal command buffer should fail");
+
+    command[0] = '\0';
+    require(!host_append_notify_command(command, sizeof(command), "Title", "Message"),
+            "small notify command buffer should fail");
+
+    command[0] = '\0';
+    require(!host_append_clip_copy_command(command, sizeof(command), "Text"),
+            "small clipboard copy command buffer should fail");
+}
+
+int main(void)
+{
+    test_reveal_command();
+    test_notify_command();
+    test_clip_copy_command();
+    test_clip_paste_command();
+    test_small_buffer_failures();
+    return 0;
+}
diff --git a/tests/test_host_common.c b/tests/test_host_common.c
new file mode 100644
index 0000000..e568ec3
--- /dev/null
+++ b/tests/test_host_common.c
@@ -0,0 +1,100 @@
+/*
+ * SPDX-FileCopyrightText: 2020-2026 Dimitris Panokostas
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "host_common.h"
+
+static void require(int condition, const char *message)
+{
+    if (!condition) {
+        fprintf(stderr, "%s\n", message);
+        exit(1);
+    }
+}
+
+static void require_string(const char *actual, const char *expected, const char *message)
+{
+    if (strcmp(actual, expected) != 0) {
+        fprintf(stderr, "%s\nexpected: %s\nactual:   %s\n", message, expected, actual);
+        exit(1);
+    }
+}
+
+static void test_append_literal(void)
+{
+    char value[8];
+
+    value[0] = '\0';
+    require(host_append_literal(value, sizeof(value), "abc"), "literal append should fit");
+    require(host_append_literal(value, sizeof(value), "def"), "second literal append should fit");
+    require_string(value, "abcdef", "literal appends should concatenate");
+
+    require(!host_append_literal(value, sizeof(value), "gh"), "oversized append should fail");
+    require_string(value, "abcdef", "failed append should leave buffer unchanged");
+}
+
+static void test_join_args(void)
+{
+    char value[32];
+    char *argv[] = {"host-notify", "Title", "hello", "world"};
+
+    value[0] = '\0';
+    require(host_join_args(value, sizeof(value), 4, argv, 2), "joined args should fit");
+    require_string(value, "hello world", "joined args should use single spaces");
+}
+
+static void test_shell_arg_quoting(void)
+{
+    char command[128];
+    int needs_quote;
+
+    command[0] = '\0';
+    require(host_append_shell_arg(command, sizeof(command), "safe-Path_1:/a+b=c,d@x", 0),
+            "safe shell arg should append");
+    require(host_append_shell_arg(command, sizeof(command), "two words", 1),
+            "spaced shell arg should append");
+    require(host_append_shell_arg(command, sizeof(command), "it's ok", 1),
+            "single quote shell arg should append");
+    require(host_append_shell_arg(command, sizeof(command), "", 1),
+            "empty shell arg should append");
+    require_string(command,
+                   "safe-Path_1:/a+b=c,d@x 'two words' 'it'\\''s ok' ''",
+                   "shell args should be safely quoted");
+
+    require(host_shell_arg_len("plain", &needs_quote) == 5, "plain arg length should match");
+    require(!needs_quote, "plain arg should not need quoting");
+    require(host_shell_arg_len("two words", &needs_quote) == 11, "quoted arg length should include quotes");
+    require(needs_quote, "spaced arg should need quoting");
+}
+
+static void test_shell_arg_buffer_failure(void)
+{
+    char command[8] = "prefix";
+
+    require(!host_append_shell_arg(command, sizeof(command), "toolong", 1),
+            "oversized shell arg should fail");
+    require_string(command, "prefix", "failed shell arg append should leave buffer unchanged");
+}
+
+static void test_uri_detection(void)
+{
+    require(host_is_uri("https://example.com"), "https URL should be treated as URI");
+    require(host_is_uri("MAILTO:user@example.com"), "URI scheme check should be case-insensitive");
+    require(host_is_uri("foo://bar"), "generic scheme with authority should be treated as URI");
+    require(!host_is_uri("Work:Docs/file.txt"), "Amiga volume path should not be treated as URI");
+    require(!host_is_uri("C:Tools/host-run"), "Amiga command path should not be treated as URI");
+}
+
+int main(void)
+{
+    test_append_literal();
+    test_join_args();
+    test_shell_arg_quoting();
+    test_shell_arg_buffer_failure();
+    test_uri_detection();
+    return 0;
+}