diff --git a/changelog.d/fixed-278.md b/changelog.d/fixed-278.md
new file mode 100644
index 0000000..2105280
--- /dev/null
+++ b/changelog.d/fixed-278.md
@@ -0,0 +1 @@
+- Bare value-taking flags (e.g. `pluk send s --text hello`, `--run-dir /tmp/x`, `--filter x`) are now rejected with exit code 2 and a `--flag=<value>` hint instead of being parsed as the string `true` (which typed `true` into the agent pane); fixes #278.
diff --git a/src/cli.ts b/src/cli.ts
index 0e1ad75..81a7710 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -58,6 +58,11 @@ ${ANSI_CYAN}Examples:${ANSI_RESET}
 `);
 }
 
+const VALUE_FLAGS = new Set([
+  'text', 'session', 'run-dir', 'cli', 'command', 'cli-args', 'rebuttal',
+  'dir', 'rationguard-bin', 'patterns-dir', 'pane', 'filter',
+]);
+
 function parseArgs(args: string[]): { positional: string[]; flags: Record<string, string> } {
   const positional: string[] = [];
   const flags: Record<string, string> = {};
@@ -68,7 +73,12 @@ function parseArgs(args: string[]): { positional: string[]; flags: Record<string
       if (eqIdx > 0) {
         flags[arg.slice(2, eqIdx)] = arg.slice(eqIdx + 1);
       } else {
-        flags[arg.slice(2)] = 'true';
+        const name = arg.slice(2);
+        if (VALUE_FLAGS.has(name)) {
+          console.error(`${paintStderr(ANSI_RED, 'Error:')} --${name} requires a value: use --${name}=<value>`);
+          process.exit(2);
+        }
+        flags[name] = 'true';
       }
     } else {
       positional.push(arg);
diff --git a/test/cli-error-paths.test.js b/test/cli-error-paths.test.js
index dafc542..1318065 100644
--- a/test/cli-error-paths.test.js
+++ b/test/cli-error-paths.test.js
@@ -311,3 +311,24 @@ test('patterns --cli=unknown warns on stderr and lists available CLIs', () => {
   assert.match(r.stderr, /no pattern set for nonesuch; available CLIs: .*omp/);
   assert.match(r.stdout, /Patterns for nonesuch:/);
 });
+
+test('bare value-taking flags exit 2 with a --flag=<value> hint', () => {
+  for (const [args, flag] of [
+    [['send', 's', '--text', 'hello'], 'text'],
+    [['attach', 's', '--run-dir', '/x'], 'run-dir'],
+    [['subscribe', 's', '--filter', 'rate_limit'], 'filter'],
+  ]) {
+    const r = spawnSync(process.execPath, [CLI, ...args], { encoding: 'utf8' });
+    assert.equal(r.status, 2, args.join(' '));
+    assert.match(r.stderr, new RegExp(`--${flag} requires a value: use --${flag}=<value>`));
+  }
+});
+
+test('bare boolean switches are still accepted', () => {
+  const r = spawnSync(process.execPath, [CLI, 'sessions', '--json'], {
+    encoding: 'utf8',
+    env: { ...process.env, PATH: `${stubBin}:${process.env.PATH}` },
+  });
+  assert.equal(r.status, 0);
+  assert.doesNotMatch(r.stderr, /requires a value/);
+});