fix(tier2): override top-level model to MiniMax-M3

The clone's opencode.json inherited the main repo's top-level 'model'
field (zai/glm-5) via 'git clone'. The tier2-autonomous agent has its
own 'model: minimax-coding-plan/MiniMax-M3' override, so the default
agent path was technically correct, but any other agent spawned without
an explicit model (or if the user manually switched to build/plan)
would have used zai/glm-5 instead of MiniMax-M3.

Fix:
1. Add top-level 'model: minimax-coding-plan/MiniMax-M3' to
   conductor/tier2/opencode.json.fragment.
2. setup_tier2_clone.ps1 merge now overrides 'model' from the fragment
   (was only overriding agent, permission, default_agent).
3. Added test_config_fragment_has_top_level_model (default-on) to
   assert the fragment's model field.
4. Added test_setup_script_overrides_model (opt-in TIER2_SANDBOX_TESTS=1)
   to assert the merge code.

All 17 tests pass (14 default-on + 3 opt-in).

Verified: re-ran setup against the live clone; opencode.json's
top-level 'model' is now minimax-coding-plan/MiniMax-M3.

conductor/tier2/opencode.json.fragment

@@ -1,6 +1,7 @@
 {
   "$schema": "https://opencode.ai/config.json",
   "default_agent": "tier2-autonomous",
+  "model": "minimax-coding-plan/MiniMax-M3",
   "permission": {
     "edit": "deny",
     "read": {

scripts/tier2/setup_tier2_clone.ps1

@@ -80,6 +80,7 @@ if ($PSCmdlet.ShouldProcess("Bootstrap Tier 2 clone at $Tier2ClonePath")) {
             if (-not $existing.permission) { $existing | Add-Member -MemberType NoteProperty -Name permission -Value ([PSCustomObject]@{}) }
             $existing.permission = $fragment.permission
             $existing | Add-Member -MemberType NoteProperty -Name default_agent -Value "tier2-autonomous" -Force
+            $existing | Add-Member -MemberType NoteProperty -Name model -Value $fragment.model -Force
             $existing | ConvertTo-Json -Depth 10 | Set-Content $cloneConfig
         } else {
             Copy-Item -Force "$MainRepoPath\conductor\tier2\opencode.json.fragment" $cloneConfig

tests/test_tier2_setup_bootstrap.py

@@ -52,3 +52,12 @@ def test_setup_script_overrides_mcp_server() -> None:
  assert "mcp.'manual-slop'.environment.PYTHONPATH" in content, "script must override MCP server PYTHONPATH"
  assert "mcp_paths.toml" in content, "script must reset mcp_paths.toml"
  assert "extra_dirs = []" in content, "script must set extra_dirs to empty"
+
+
+def test_setup_script_overrides_model() -> None:
+ """Regression test: setup_tier2_clone.ps1 MUST override the top-level
+ 'model' field in the clone's opencode.json to the Tier 2 model
+ (minimax-coding-plan/MiniMax-M3), not the main repo's zai/glm-5."""
+ script = Path("scripts/tier2/setup_tier2_clone.ps1").resolve()
+ content = script.read_text(encoding="utf-8")
+ assert 'Name model -Value $fragment.model' in content, "script must override top-level model from fragment"

tests/test_tier2_slash_command_spec.py

@@ -89,6 +89,18 @@ def test_config_fragment_valid_json() -> None:
  assert "git reset*" in perms["bash"]
 
 
+def test_config_fragment_has_top_level_model() -> None:
+ """Top-level model MUST be minimax-coding-plan/MiniMax-M3 (the Tier 2
+ model), NOT the main repo's zai/glm-5. Regression test for the bug
+ where the clone inherited the main repo's default model and Tier 2
+ ran on zai/glm-5 instead of MiniMax-M3 (2026-06-17)."""
+ data = json.loads(CONFIG_PATH.read_text(encoding="utf-8"))
+ assert "model" in data, "top-level model field is required"
+ assert data["model"] == "minimax-coding-plan/MiniMax-M3", (
+  f"top-level model must be MiniMax-M3, got: {data['model']}"
+ )
+
+
 def test_config_fragment_has_top_level_permission() -> None:
  """Top-level permission.read/write MUST allow the sandbox dirs (added
  2026-06-17 after the bug where the agent's permission.read was not