diff --git a/plugins/voyage/lib/parsers/arg-parser.mjs b/plugins/voyage/lib/parsers/arg-parser.mjs
index 7dbafd3..c843eb1 100644
--- a/plugins/voyage/lib/parsers/arg-parser.mjs
+++ b/plugins/voyage/lib/parsers/arg-parser.mjs
@@ -7,33 +7,33 @@
 const FLAG_SCHEMA = {
   trekbrief: {
     boolean: ['--quick', '--fg'],
-    valued: [],
+    valued: ['--profile'],
     aliases: {},
   },
   trekresearch: {
     boolean: ['--quick', '--local', '--external', '--fg'],
-    valued: ['--project'],
+    valued: ['--project', '--profile'],
     aliases: {},
   },
   trekplan: {
     boolean: ['--quick', '--fg'],
-    valued: ['--project', '--brief', '--export', '--decompose'],
+    valued: ['--project', '--brief', '--export', '--decompose', '--profile'],
     multi: ['--research'],
     aliases: {},
   },
   trekexecute: {
     boolean: ['--resume', '--dry-run', '--validate', '--fg'],
-    valued: ['--project', '--step', '--session'],
+    valued: ['--project', '--step', '--session', '--profile'],
     aliases: {},
   },
   trekreview: {
     boolean: ['--quick', '--fg', '--dry-run', '--validate'],
-    valued: ['--project', '--since'],
+    valued: ['--project', '--since', '--profile'],
     aliases: {},
   },
   trekcontinue: {
     boolean: ['--help', '--cleanup', '--confirm', '--dry-run'],
-    valued: [],
+    valued: ['--profile'],
     aliases: {},
   },
 };
diff --git a/plugins/voyage/tests/parsers/arg-parser-profile.test.mjs b/plugins/voyage/tests/parsers/arg-parser-profile.test.mjs
new file mode 100644
index 0000000..7224341
--- /dev/null
+++ b/plugins/voyage/tests/parsers/arg-parser-profile.test.mjs
@@ -0,0 +1,53 @@
+// tests/parsers/arg-parser-profile.test.mjs
+// SC #4: --profile valued flag MUST be recognized on all 6 voyage commands.
+
+import { test } from 'node:test';
+import { strict as assert } from 'node:assert';
+import { parseArgs } from '../../lib/parsers/arg-parser.mjs';
+
+const COMMANDS = ['trekbrief', 'trekresearch', 'trekplan', 'trekexecute', 'trekreview', 'trekcontinue'];
+
+for (const cmd of COMMANDS) {
+  test(`${cmd} — --profile economy parses as valued`, () => {
+    const r = parseArgs('--profile economy', cmd);
+    assert.equal(r.flags['--profile'], 'economy', `${cmd} should accept --profile economy`);
+    assert.equal(r.errors.length, 0, `${cmd} should have no errors`);
+    assert.equal(r.unknown.length, 0, `${cmd} should not mark --profile as unknown`);
+  });
+}
+
+test('trekplan — --profile without value emits ARG_MISSING_VALUE', () => {
+  const r = parseArgs('--profile', 'trekplan');
+  const missing = r.errors.find((e) => e.code === 'ARG_MISSING_VALUE');
+  assert.ok(missing, 'must surface ARG_MISSING_VALUE');
+  assert.match(missing.message, /--profile/);
+});
+
+test('trekplan — --profile economy --quick combines correctly', () => {
+  const r = parseArgs('--profile economy --quick', 'trekplan');
+  assert.equal(r.flags['--profile'], 'economy');
+  assert.equal(r.flags['--quick'], true);
+});
+
+test('trekplan — --profile economy --gates open: --gates is unknown (parsed inline by command prose, not in FLAG_SCHEMA)', () => {
+  // Edge case from plan.md Step 2 (per plan-critic minor): --gates is intentionally
+  // NOT in FLAG_SCHEMA; commands parse it inline. Verify --profile still parses cleanly
+  // and --gates ends up in unknown[] / positional[] rather than colliding with --profile.
+  const r = parseArgs('--profile economy --gates open', 'trekplan');
+  assert.equal(r.flags['--profile'], 'economy');
+  // --gates is unknown to FLAG_SCHEMA; it lands in unknown[] and 'open' becomes positional
+  assert.ok(r.unknown.includes('--gates'), `expected --gates in unknown, got: ${JSON.stringify(r.unknown)}`);
+  assert.ok(r.positional.includes('open'), `expected 'open' as positional, got: ${JSON.stringify(r.positional)}`);
+});
+
+test('trekexecute — --profile balanced --project /tmp/p combines correctly', () => {
+  const r = parseArgs('--profile balanced --project /tmp/p', 'trekexecute');
+  assert.equal(r.flags['--profile'], 'balanced');
+  assert.equal(r.flags['--project'], '/tmp/p');
+});
+
+test('trekcontinue — --profile premium parses without --project', () => {
+  // trekcontinue had empty valued[] before v4.1 — sanity check the array is now extended
+  const r = parseArgs('--profile premium', 'trekcontinue');
+  assert.equal(r.flags['--profile'], 'premium');
+});