fix: handle agent frontmatter correctly in OpenCode conversion (#981)

convertClaudeToOpencodeFrontmatter() was designed for commands but is
also called for agents. For agents it incorrectly strips name: (needed
by OpenCode agents), keeps color:/skills:/tools: (should strip), and
doesn't add model: inherit / mode: subagent (required by OpenCode).

Add isAgent option to convertClaudeToOpencodeFrontmatter() so agent
installs get correct frontmatter: name preserved, Claude-only fields
stripped, model/mode injected. Command conversion unchanged (default).

Includes 14 test cases covering agent and command conversion paths.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

tests/opencode-agent-conversion.test.cjs

@@ -0,0 +1,143 @@
+/**
+ * OpenCode Agent Frontmatter Conversion Tests
+ *
+ * Validates that convertClaudeToOpencodeFrontmatter correctly converts
+ * agent frontmatter for OpenCode compatibility when isAgent: true.
+ *
+ * Bug: Without isAgent flag, the function strips name: (agents need it),
+ * keeps color:/skills:/tools: record (should strip), and doesn't add
+ * model: inherit / mode: subagent (required by OpenCode agents).
+ */
+
+const { test, describe } = require('node:test');
+const assert = require('node:assert');
+
+process.env.GSD_TEST_MODE = '1';
+const { convertClaudeToOpencodeFrontmatter } = require('../bin/install.js');
+
+// Sample Claude agent frontmatter (matches actual GSD agent format)
+const SAMPLE_AGENT = `---
+name: gsd-executor
+description: Executes GSD plans with atomic commits
+tools: Read, Write, Edit, Bash, Grep, Glob
+color: yellow
+skills:
+  - gsd-executor-workflow
+# hooks:
+#   PostToolUse:
+#     - matcher: "Write|Edit"
+#       hooks:
+#         - type: command
+#           command: "npx eslint --fix $FILE 2>/dev/null || true"
+---
+
+<role>
+You are a GSD plan executor.
+</role>`;
+
+// Sample Claude command frontmatter (for comparison — commands work differently)
+const SAMPLE_COMMAND = `---
+name: gsd-execute-phase
+description: Execute all plans in a phase
+allowed-tools:
+  - Read
+  - Write
+  - Bash
+---
+
+Execute the phase plan.`;
+
+describe('OpenCode agent conversion (isAgent: true)', () => {
+  test('keeps name: field for agents', () => {
+    const result = convertClaudeToOpencodeFrontmatter(SAMPLE_AGENT, { isAgent: true });
+    const frontmatter = result.split('---')[1];
+    assert.ok(frontmatter.includes('name: gsd-executor'), 'name: should be preserved for agents');
+  });
+
+  test('adds model: inherit', () => {
+    const result = convertClaudeToOpencodeFrontmatter(SAMPLE_AGENT, { isAgent: true });
+    const frontmatter = result.split('---')[1];
+    assert.ok(frontmatter.includes('model: inherit'), 'model: inherit should be added');
+  });
+
+  test('adds mode: subagent', () => {
+    const result = convertClaudeToOpencodeFrontmatter(SAMPLE_AGENT, { isAgent: true });
+    const frontmatter = result.split('---')[1];
+    assert.ok(frontmatter.includes('mode: subagent'), 'mode: subagent should be added');
+  });
+
+  test('strips tools: field', () => {
+    const result = convertClaudeToOpencodeFrontmatter(SAMPLE_AGENT, { isAgent: true });
+    const frontmatter = result.split('---')[1];
+    assert.ok(!frontmatter.includes('tools:'), 'tools: should be stripped for agents');
+    assert.ok(!frontmatter.includes('read: true'), 'tools object should not be generated');
+  });
+
+  test('strips skills: array', () => {
+    const result = convertClaudeToOpencodeFrontmatter(SAMPLE_AGENT, { isAgent: true });
+    const frontmatter = result.split('---')[1];
+    assert.ok(!frontmatter.includes('skills:'), 'skills: should be stripped');
+    assert.ok(!frontmatter.includes('gsd-executor-workflow'), 'skill entries should be stripped');
+  });
+
+  test('strips color: field', () => {
+    const result = convertClaudeToOpencodeFrontmatter(SAMPLE_AGENT, { isAgent: true });
+    const frontmatter = result.split('---')[1];
+    assert.ok(!frontmatter.includes('color:'), 'color: should be stripped for agents');
+  });
+
+  test('strips commented hooks block', () => {
+    const result = convertClaudeToOpencodeFrontmatter(SAMPLE_AGENT, { isAgent: true });
+    const frontmatter = result.split('---')[1];
+    assert.ok(!frontmatter.includes('# hooks:'), 'commented hooks should be stripped');
+    assert.ok(!frontmatter.includes('PostToolUse'), 'hook content should be stripped');
+  });
+
+  test('keeps description: field', () => {
+    const result = convertClaudeToOpencodeFrontmatter(SAMPLE_AGENT, { isAgent: true });
+    const frontmatter = result.split('---')[1];
+    assert.ok(frontmatter.includes('description: Executes GSD plans'), 'description should be kept');
+  });
+
+  test('preserves body content', () => {
+    const result = convertClaudeToOpencodeFrontmatter(SAMPLE_AGENT, { isAgent: true });
+    assert.ok(result.includes('<role>'), 'body should be preserved');
+    assert.ok(result.includes('You are a GSD plan executor.'), 'body content should be intact');
+  });
+
+  test('applies body text replacements', () => {
+    const agentWithClaudePaths = `---
+name: test-agent
+description: Test
+tools: Read
+---
+
+Read ~/.claude/agent-memory/ for context.
+Use $HOME/.claude/skills/ for reference.`;
+
+    const result = convertClaudeToOpencodeFrontmatter(agentWithClaudePaths, { isAgent: true });
+    assert.ok(result.includes('~/.config/opencode/agent-memory/'), '~/.claude should be replaced');
+    assert.ok(result.includes('$HOME/.config/opencode/skills/'), '$HOME/.claude should be replaced');
+  });
+});
+
+describe('OpenCode command conversion (isAgent: false, default)', () => {
+  test('strips name: field for commands', () => {
+    const result = convertClaudeToOpencodeFrontmatter(SAMPLE_COMMAND);
+    const frontmatter = result.split('---')[1];
+    assert.ok(!frontmatter.includes('name:'), 'name: should be stripped for commands');
+  });
+
+  test('does not add model: or mode: for commands', () => {
+    const result = convertClaudeToOpencodeFrontmatter(SAMPLE_COMMAND);
+    const frontmatter = result.split('---')[1];
+    assert.ok(!frontmatter.includes('model:'), 'model: should not be added for commands');
+    assert.ok(!frontmatter.includes('mode:'), 'mode: should not be added for commands');
+  });
+
+  test('keeps description: for commands', () => {
+    const result = convertClaudeToOpencodeFrontmatter(SAMPLE_COMMAND);
+    const frontmatter = result.split('---')[1];
+    assert.ok(frontmatter.includes('description:'), 'description should be kept');
+  });
+});