diff --git a/completions/bun.bash b/completions/bun.bash
index 7040f0ca51b2..d13fccfde3b2 100644
--- a/completions/bun.bash
+++ b/completions/bun.bash
@@ -53,24 +53,21 @@ _read_scripts_in_package_json() {
         COMPREPLY+=( $(compgen -W "${package_json_compreply[*]}" -- "${cur_word}") );
     }
 
-    # when a script is passed as an option, do not show other scripts as part of the completion anymore
-    local re_prev_script="(^| )${prev}($| )";
-    [[
-        ( "${COMPREPLY[*]}" =~ ${re_prev_script} && -n "${COMP_WORDS[2]}" ) || \
-            ( "${COMPREPLY[*]}" =~ ${re_comp_word_script} )
-    ]] && {
-        local filtered_reply=();
-        local reply_word script_name keep;
-        for reply_word in "${COMPREPLY[@]}"; do
-            keep=1;
-            for script_name in "${package_json_compreply[@]}"; do
-                [[ "${reply_word}" == "${script_name}" ]] && { keep=""; break; };
-            done
-            [[ -n "${keep}" ]] && filtered_reply+=( "${reply_word}" );
+    # Do not offer package.json scripts once a script/file has already been typed. This block used
+    # to be gated on a regex match against an undeclared variable, which made it unconditional under
+    # GNU regex and an "empty (sub)expression" error under BSD regex (#24847); running it
+    # unconditionally preserves the long-standing GNU behaviour portably.
+    local filtered_reply=();
+    local reply_word script_name keep;
+    for reply_word in "${COMPREPLY[@]}"; do
+        keep=1;
+        for script_name in "${package_json_compreply[@]}"; do
+            [[ "${reply_word}" == "${script_name}" ]] && { keep=""; break; };
         done
-        COMPREPLY=( "${filtered_reply[@]}" );
-        replaced_script="${prev}";
-    }
+        [[ -n "${keep}" ]] && filtered_reply+=( "${reply_word}" );
+    done
+    COMPREPLY=( "${filtered_reply[@]}" );
+    replaced_script="${prev}";
 }
 
 
diff --git a/completions/bun.fish b/completions/bun.fish
index 6b2dc5bc9bcd..6d5e7ef255dc 100644
--- a/completions/bun.fish
+++ b/completions/bun.fish
@@ -32,8 +32,8 @@ function __fish__get_bun_bun_js_files
 	string split ' ' (bun getcompletes j)
 end
 
-set -l bun_install_boolean_flags yarn production optional development no-save dry-run force no-cache silent verbose global
-set -l bun_install_boolean_flags_descriptions "Write a yarn.lock file (yarn v1)" "Don't install devDependencies" "Add dependency to optionalDependencies" "Add dependency to devDependencies" "Don't update package.json or save a lockfile" "Don't install anything" "Always request the latest versions from the registry & reinstall all dependencies" "Ignore manifest cache entirely" "Don't output anything" "Excessively verbose logging" "Use global folder"
+set -l bun_install_boolean_flags yarn production optional development no-save frozen-lockfile dry-run force no-cache silent verbose global
+set -l bun_install_boolean_flags_descriptions "Write a yarn.lock file (yarn v1)" "Don't install devDependencies" "Add dependency to optionalDependencies" "Add dependency to devDependencies" "Don't update package.json or save a lockfile" "Disallow changes to lockfile" "Perform a dry run without making changes" "Always request the latest versions from the registry & reinstall all dependencies" "Ignore manifest cache entirely" "Don't output anything" "Excessively verbose logging" "Use global folder"
 
 set -l bun_builtin_cmds_without_run dev create help bun upgrade discord install remove add update init pm x repl
 set -l bun_builtin_cmds_accepting_flags create help bun upgrade discord run init link unlink pm x update
diff --git a/completions/bun.zsh b/completions/bun.zsh
index 9ab15deedf66..9ea31c69a520 100644
--- a/completions/bun.zsh
+++ b/completions/bun.zsh
@@ -483,7 +483,7 @@ _bun_run_completion() {
         '--watch[Automatically restart bun'"'"'s JavaScript runtime on file change]' \
         '--no-install[Disable auto install in bun'"'"'s JavaScript runtime]' \
         '--install[Install dependencies automatically when no node_modules are present, default: "auto". "force" to ignore node_modules, fallback to install any missing]: :->install_' \
-        '-i[Automatically install dependencies and use global cache in bun'"'"'s runtime, equivalent to --install=fallback'] \
+        '-i[Automatically install dependencies and use global cache in bun'"'"'s runtime, equivalent to --install=fallback]' \
         '--prefer-offline[Skip staleness checks for packages in bun'"'"'s JavaScript runtime and resolve from disk]' \
         '--prefer-latest[Use the latest matching versions of packages in bun'"'"'s JavaScript runtime, always checking npm]' \
         '--silent[Don'"'"'t repeat the command for bun run]' \
@@ -991,7 +991,7 @@ _set_remove() {
 _bun_add_param_package_completion() {
 
     IFS=$'\n' inexact=($(history -n bun | grep -E "^bun add " | cut -c 9- | uniq))
-    IFS=$'\n' exact=($($inexact | grep -E "^$words[$CURRENT]"))
+    IFS=$'\n' exact=($(print -l -- $inexact | grep -E "^$words[$CURRENT]"))
     IFS=$'\n' packages=($(SHELL=zsh bun getcompletes a $words[$CURRENT]))
 
     to_print=$inexact
diff --git a/test/cli/shell-completion-scripts.test.ts b/test/cli/shell-completion-scripts.test.ts
new file mode 100644
index 000000000000..ca664c3397b3
--- /dev/null
+++ b/test/cli/shell-completion-scripts.test.ts
@@ -0,0 +1,141 @@
+import { describe, expect, test } from "bun:test";
+import { bunEnv, bunExe, isWindows, tempDir } from "harness";
+
+// `bun completions` writes the embedded completion script for the shell named
+// by $SHELL to stdout when stdout is not a TTY. This lets us assert on the
+// bytes that ship inside the binary (from completions/bun.{zsh,bash,fish}).
+// HOME / BUN_INSTALL are cleared so the `install_bunx_symlink` step that runs
+// before the piped-stdout write has nowhere outside the build tree to land.
+async function emitCompletions(shell: "zsh" | "bash" | "fish"): Promise<string> {
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), "completions"],
+    env: {
+      ...bunEnv,
+      SHELL: `/bin/${shell}`,
+      IS_BUN_AUTO_UPDATE: undefined,
+      HOME: undefined,
+      BUN_INSTALL: undefined,
+    },
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+  const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+  expect(stderr).not.toContain("error");
+  expect(exitCode).toBe(0);
+  return stdout;
+}
+
+// completions/bun.bash uses `declare -A` (associative arrays, bash >= 4.0).
+// macOS ships /bin/bash 3.2, so the functional probe can only run where a
+// modern bash is on PATH.
+const bashMajor = (() => {
+  if (isWindows) return 0;
+  try {
+    const { stdout } = Bun.spawnSync({ cmd: ["bash", "-c", "echo ${BASH_VERSINFO[0]}"], env: bunEnv });
+    return parseInt(stdout.toString().trim(), 10) || 0;
+  } catch {
+    return 0;
+  }
+})();
+
+// `bun completions` is a no-op on Windows (PowerShell completions are not
+// implemented), so these tests can only run on POSIX.
+describe.skipIf(isWindows)("shell completion scripts", () => {
+  test.concurrent("zsh: -i optspec has closing bracket inside the quote", async () => {
+    // #31665: the line was `...=fallback'] \` (bracket outside the quote),
+    // which zsh _arguments sees as a stray literal `]` argument.
+    const script = await emitCompletions("zsh");
+    expect(script).toContain("--install=fallback]' \\");
+    expect(script).not.toContain("--install=fallback'] \\");
+  });
+
+  test.concurrent("zsh: _bun_add_param_package_completion prints history instead of executing it", async () => {
+    // #34062: `$($inexact | grep ...)` runs the first history entry as a
+    // command. It should be `$(print -l -- $inexact | grep ...)`.
+    const script = await emitCompletions("zsh");
+    expect(script).toContain("print -l -- $inexact | grep");
+    expect(script).not.toContain("($($inexact | grep");
+  });
+
+  test.concurrent("bash: no reference to undeclared re_comp_word_script", async () => {
+    // #28744 / #24847: ${re_comp_word_script} was never defined; under BSD
+    // regex (macOS bash) `=~ <empty>` is rejected as "empty (sub)expression".
+    const script = await emitCompletions("bash");
+    expect(script).not.toContain("${re_comp_word_script}");
+  });
+
+  test.concurrent.skipIf(bashMajor < 1)("bash: script passes bash -n", async () => {
+    const script = await emitCompletions("bash");
+    using dir = tempDir("bun-bash-completion", { "bun.bash": script });
+    await using proc = Bun.spawn({
+      cmd: ["bash", "-n", "bun.bash"],
+      cwd: String(dir),
+      env: bunEnv,
+      stdout: "pipe",
+      stderr: "pipe",
+    });
+    const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+    expect(stderr).toBe("");
+    expect(stdout).toBe("");
+    expect(exitCode).toBe(0);
+  });
+
+  // Drives _bun_completions directly. Skipped when PATH bash is < 4 (macOS
+  // stock /bin/bash is 3.2 and rejects the script's `declare -A`).
+  test.concurrent.skipIf(bashMajor < 4)("bash: `bun <entrypoint> <TAB>` still offers global flags", async () => {
+    // Regression guard for the #24847 fix: the removed guard was always-true
+    // under GNU regex, so the `replaced_script` assignment it protected has
+    // always run. Dropping the arm outright would leave `bun somefile.js <TAB>`
+    // with zero completions instead of the global flag list, so the fix makes
+    // the block unconditional instead.
+    const script = await emitCompletions("bash");
+    using dir = tempDir("bun-bash-completion-run", {
+      "bun.bash": script,
+      "probe.sh":
+        "source ./bun.bash\n" +
+        'COMP_WORDS=(bun somefile.js "")\n' +
+        "COMP_CWORD=2\n" +
+        "COMPREPLY=()\n" +
+        "_bun_completions\n" +
+        'echo "count=${#COMPREPLY[@]}"\n' +
+        "printf '%s\\n' \"${COMPREPLY[@]}\"\n",
+    });
+    await using proc = Bun.spawn({
+      cmd: ["bash", "probe.sh"],
+      cwd: String(dir),
+      env: bunEnv,
+      stdout: "pipe",
+      stderr: "pipe",
+    });
+    const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+    expect(stderr).toBe("");
+    const lines = stdout.trim().split("\n");
+    expect(lines[0]).toMatch(/^count=\d+$/);
+    expect(Number(lines[0].slice("count=".length))).toBeGreaterThan(0);
+    expect(lines).toContain("--help");
+    expect(lines).toContain("--version");
+    expect(exitCode).toBe(0);
+  });
+
+  test.concurrent("fish: install boolean flags include frozen-lockfile and descriptions line up", async () => {
+    // #29364: frozen-lockfile was missing and dry-run's description was wrong.
+    const script = await emitCompletions("fish");
+    const flagsLine = script.split("\n").find(l => l.startsWith("set -l bun_install_boolean_flags "));
+    const descLine = script.split("\n").find(l => l.startsWith("set -l bun_install_boolean_flags_descriptions "));
+    expect(flagsLine).toBeDefined();
+    expect(descLine).toBeDefined();
+
+    const flags = flagsLine!.replace("set -l bun_install_boolean_flags ", "").trim().split(/\s+/);
+    // Descriptions are a flat sequence of "..." literals separated by spaces.
+    const descs = [...descLine!.matchAll(/"([^"]*)"/g)].map(m => m[1]);
+
+    // The two parallel lists are zipped by index at runtime; length equality
+    // alone cannot catch an insertion at the wrong position, so spot-check
+    // the pairings this change touched as well.
+    expect(descs.length).toBe(flags.length);
+    expect(flags).toContain("frozen-lockfile");
+    expect(descs[flags.indexOf("frozen-lockfile")]).toContain("lockfile");
+    expect(descs[flags.indexOf("dry-run")]).toMatch(/dry run/i);
+    expect(descs[flags.indexOf("global")]).toMatch(/global/i);
+  });
+});