fix(#442): --config-dir= no longer truncates paths containing equals signs (#475)

Extract a pure `parseConfigDirFromArgs(argsArray)` seam from the
closure-based `parseConfigDirArg()` and fix the equals-form parser to
use `slice(indexOf('=') + 1)` instead of `split('=')[1]`, so that
paths like `/tmp/gsd=a` or `/tmp/a=b=c` are preserved in full.

Both `--config-dir=<path>` and `-c=<path>` are fixed.  The pure seam
is exported via `module.exports` so the 12-case unit test can assert
on typed return values without spawning a child process.

Co-authored-by: CI Rebase Check <ci@gsd-redux>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/bug-442-config-dir-equals-in-path.test.cjs

@@ -0,0 +1,99 @@
+'use strict';
+const { test, describe } = require('node:test');
+const assert = require('node:assert/strict');
+
+// parseConfigDirArg is not exported directly from bin/install.js (it closes
+// over the module-level `args` array).  We expose a pure seam here:
+// parseConfigDirFromArgs(args) that mirrors the function's logic so we can
+// test the equals-form parsing without spawning a child process.
+//
+// The implementation under test is inlined below (RED: before the fix it will
+// reproduce the truncation bug).  Once the fix lands, we swap in the real
+// implementation via require.
+
+/**
+ * Pure seam that replicates the equals-form parse logic from bin/install.js.
+ * We import it via a thin wrapper so that the function can be tested without
+ * executing the entire install script.
+ *
+ * During RED the bug is: `split('=')[1]` drops everything after the second `=`.
+ */
+const { parseConfigDirFromArgs } = require('../bin/install.js');
+
+describe('bug-442: --config-dir= equals-form path parsing', () => {
+  // ── Happy-path: single = in path ─────────────────────────────────────────
+  test('--config-dir=<path> with one = in value returns full value', () => {
+    const result = parseConfigDirFromArgs(['--config-dir=/tmp/gsd=a']);
+    assert.equal(result, '/tmp/gsd=a');
+  });
+
+  // ── Happy-path: multiple = in path ───────────────────────────────────────
+  test('--config-dir=<path> with multiple = in value returns full value', () => {
+    const result = parseConfigDirFromArgs(['--config-dir=/tmp/a=b=c']);
+    assert.equal(result, '/tmp/a=b=c');
+  });
+
+  // ── Short form -c= ────────────────────────────────────────────────────────
+  test('-c=<path> with = in value returns full value', () => {
+    const result = parseConfigDirFromArgs(['-c=/tmp/gsd=a']);
+    assert.equal(result, '/tmp/gsd=a');
+  });
+
+  test('-c=<path> with multiple = in value returns full value', () => {
+    const result = parseConfigDirFromArgs(['-c=/tmp/a=b=c']);
+    assert.equal(result, '/tmp/a=b=c');
+  });
+
+  // ── Contract: empty value ─────────────────────────────────────────────────
+  // --config-dir= (no value after the =) → returns empty string ''.
+  // The caller (parseConfigDirArg) treats '' as missing and errors; the seam
+  // itself should faithfully return '' rather than null/undefined so the
+  // caller can make the error decision.
+  test('--config-dir= with no value returns empty string', () => {
+    const result = parseConfigDirFromArgs(['--config-dir=']);
+    assert.equal(result, '');
+  });
+
+  test('-c= with no value returns empty string', () => {
+    const result = parseConfigDirFromArgs(['-c=']);
+    assert.equal(result, '');
+  });
+
+  // ── Space-separated form is unaffected (regression guard) ─────────────────
+  test('--config-dir <path> space-separated still returns the path', () => {
+    const result = parseConfigDirFromArgs(['--config-dir', '/tmp/gsd=a']);
+    assert.equal(result, '/tmp/gsd=a');
+  });
+
+  test('-c <path> space-separated still returns the path', () => {
+    const result = parseConfigDirFromArgs(['-c', '/tmp/gsd=a']);
+    assert.equal(result, '/tmp/gsd=a');
+  });
+
+  // ── No config-dir flag → null ─────────────────────────────────────────────
+  test('returns null when no --config-dir flag is present', () => {
+    const result = parseConfigDirFromArgs(['--global', '--claude']);
+    assert.equal(result, null);
+  });
+
+  // ── Negative matrix (CLI edge cases) ─────────────────────────────────────
+  // Flag-looking value after space form: next arg starts with - → null (no
+  // valid value; the real function would process.exit but the seam returns null
+  // so tests stay in-process).
+  test('space form with next arg being a flag returns null (flag-looking value)', () => {
+    const result = parseConfigDirFromArgs(['--config-dir', '--other-flag']);
+    assert.equal(result, null);
+  });
+
+  // Equals form where value is a path with no = (plain path, no regression)
+  test('--config-dir=<plain-path> without any = in path still works', () => {
+    const result = parseConfigDirFromArgs(['--config-dir=/tmp/plain']);
+    assert.equal(result, '/tmp/plain');
+  });
+
+  // Flag appears after other args (positional ordering should not matter)
+  test('--config-dir= flag after other args is parsed correctly', () => {
+    const result = parseConfigDirFromArgs(['--global', '--config-dir=/tmp/a=b', '--claude']);
+    assert.equal(result, '/tmp/a=b');
+  });
+});