diff --git a/agent/tests/reliability/test_environment_contract.py b/agent/tests/reliability/test_environment_contract.py
new file mode 100644
index 00000000..aa44e0e3
--- /dev/null
+++ b/agent/tests/reliability/test_environment_contract.py
@@ -0,0 +1,146 @@
+"""Phase 0.5 readiness checks for the IRR-AGL environment contract."""
+
+from __future__ import annotations
+
+import importlib.util
+import os
+from pathlib import Path
+
+import pydantic
+
+
+REPO_ROOT = Path(__file__).resolve().parents[3]
+INVENTORY_SCRIPT = REPO_ROOT / "agent" / "scripts" / "dump_tool_inventory.py"
+VALID_MODES = {"off", "observe", "warn", "enforce"}
+
+
+def _expand_config_path(raw: str) -> Path:
+    return Path(os.path.expandvars(os.path.expanduser(raw))).resolve(strict=False)
+
+
+def _default_artifact_root() -> Path:
+    return (Path.home() / ".vibe-trading" / "artifacts").resolve(strict=False)
+
+
+def _default_ledger_path() -> Path:
+    return (Path.home() / ".vibe-trading" / "research-ledger" / "ledger.sqlite").resolve(strict=False)
+
+
+def _parse_mode(raw: str | None, *, default: str = "observe") -> str:
+    value = (raw or default).strip().lower()
+    if value not in VALID_MODES:
+        raise ValueError(f"unsupported IRR-AGL mode: {raw!r}")
+    return value
+
+
+def _load_inventory_module():
+    spec = importlib.util.spec_from_file_location("dump_tool_inventory", INVENTORY_SCRIPT)
+    assert spec is not None
+    assert spec.loader is not None
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+
+
+def test_pydantic_major_version_is_2() -> None:
+    assert int(pydantic.VERSION.split(".", 1)[0]) == 2
+
+
+def test_scipy_is_importable() -> None:
+    scipy_spec = importlib.util.find_spec("scipy")
+
+    assert scipy_spec is not None
+
+
+def test_default_artifact_root_resolves_under_user_home() -> None:
+    artifact_root = _default_artifact_root()
+
+    artifact_root.relative_to(Path.home().resolve(strict=False))
+    assert artifact_root.name == "artifacts"
+    assert artifact_root.parent.name == ".vibe-trading"
+
+
+def test_artifact_root_override_can_resolve_outside_user_home(tmp_path: Path, monkeypatch) -> None:
+    override = tmp_path / "custom-artifacts"
+    monkeypatch.setenv("VIBE_TRADING_ARTIFACT_ROOT", str(override))
+
+    resolved = _expand_config_path(os.environ["VIBE_TRADING_ARTIFACT_ROOT"])
+
+    assert resolved == override.resolve(strict=False)
+
+
+def test_default_ledger_path_resolves_under_user_home() -> None:
+    ledger_path = _default_ledger_path()
+
+    ledger_path.relative_to(Path.home().resolve(strict=False))
+    assert ledger_path.name == "ledger.sqlite"
+    assert ledger_path.parent.name == "research-ledger"
+    assert ledger_path.parent.parent.name == ".vibe-trading"
+
+
+def test_ledger_path_override_can_resolve_outside_user_home(tmp_path: Path, monkeypatch) -> None:
+    override = tmp_path / "research-ledger" / "ledger.sqlite"
+    monkeypatch.setenv("VIBE_TRADING_RESEARCH_LEDGER_PATH", str(override))
+
+    resolved = _expand_config_path(os.environ["VIBE_TRADING_RESEARCH_LEDGER_PATH"])
+
+    assert resolved == override.resolve(strict=False)
+
+
+def test_platform_path_expansion_smoke(tmp_path: Path, monkeypatch) -> None:
+    monkeypatch.setenv("VIBE_TRADING_TEST_HOME", str(tmp_path))
+    raw = (
+        r"%VIBE_TRADING_TEST_HOME%\artifacts"
+        if os.name == "nt"
+        else "$VIBE_TRADING_TEST_HOME/artifacts"
+    )
+
+    resolved = _expand_config_path(raw)
+
+    assert resolved == (tmp_path / "artifacts").resolve(strict=False)
+
+
+def test_reliability_and_governance_feature_modes_accept_baseline_values() -> None:
+    for env_name in ("VIBE_TRADING_RELIABILITY_MODE", "VIBE_TRADING_GOVERNANCE_MODE"):
+        for mode in ("off", "observe", "warn", "enforce"):
+            assert _parse_mode(mode) == mode
+            assert _parse_mode(mode.upper()) == mode
+
+
+def test_current_cli_package_is_discoverable() -> None:
+    cli_spec = importlib.util.find_spec("cli")
+    cli_main_spec = importlib.util.find_spec("cli.main")
+
+    assert cli_spec is not None
+    assert cli_main_spec is not None
+
+
+def test_dump_tool_inventory_output_has_stable_required_fields() -> None:
+    module = _load_inventory_module()
+
+    rows = module.build_tool_inventory()
+
+    assert rows
+    assert [row["name"] for row in rows] == sorted(row["name"] for row in rows)
+
+    required_fields = {
+        "name",
+        "module",
+        "class_name",
+        "is_readonly",
+        "repeatable",
+        "surface_guess",
+        "risk_guess",
+    }
+    allowed_risks = {"R0_READ", "R1_WRITE_LOCAL", "R2_NETWORK", "R3_TRADE_READ", "R4_TRADE_WRITE", "R5_SHELL"}
+    allowed_surfaces = {"filesystem", "live_connector", "local_cli", "local_research", "mcp", "network_data"}
+
+    for row in rows:
+        assert required_fields <= row.keys()
+        assert isinstance(row["name"], str) and row["name"]
+        assert isinstance(row["module"], str) and row["module"]
+        assert isinstance(row["class_name"], str) and row["class_name"]
+        assert isinstance(row["is_readonly"], bool)
+        assert isinstance(row["repeatable"], bool)
+        assert row["surface_guess"] in allowed_surfaces
+        assert row["risk_guess"] in allowed_risks