diff --git a/omnigent/onboarding/harness_install.py b/omnigent/onboarding/harness_install.py
index 5f84a1f7..035792cc 100644
--- a/omnigent/onboarding/harness_install.py
+++ b/omnigent/onboarding/harness_install.py
@@ -201,17 +201,17 @@ _HARNESS_INSTALL: dict[str, HarnessInstallSpec] = {
         # ``pi >= 0.79.0``; older CLIs would prompt mid-session.
         min_version=_PI_MIN_VERSION,
     ),
-    # Pin the install to the supported 1.17.x range: opencode-ai's npm ``latest``
+    # Pin the install to the supported 1.18.x range: opencode-ai's npm ``latest``
     # is a ``0.0.0-beta-*`` pre-release, so a bare ``opencode-ai`` would install a
     # version the runtime version-check (``check_opencode_version``,
-    # >=1.17.7,<1.18.0) then rejects. ``~1.17.7`` mirrors that exact range.
+    # >=1.17.7,<1.19.0) then rejects. ``~1.18.0`` resolves to the latest 1.18.x.
     # The same version bounds are enforced in setup via ``min_version`` /
     # ``max_version_exclusive`` so the install/upgrade prompt fires before
     # the runtime gate does.
     OPENCODE_KEY: HarnessInstallSpec(
         "OpenCode",
         "opencode",
-        "opencode-ai@~1.17.7",
+        "opencode-ai@~1.18.0",
         min_version=OPENCODE_MIN_VERSION,
         max_version_exclusive=OPENCODE_MAX_VERSION_EXCLUSIVE,
     ),
diff --git a/omnigent/opencode_native_client.py b/omnigent/opencode_native_client.py
index 0e40818c..39e89084 100644
--- a/omnigent/opencode_native_client.py
+++ b/omnigent/opencode_native_client.py
@@ -1,6 +1,6 @@
 """Typed HTTP + SSE client for an ``opencode serve`` native server.
 
-Shaped from the pinned OpenCode OpenAPI (``opencode`` 1.17.x,
+Shaped from the pinned OpenCode OpenAPI (``opencode`` 1.17.x–1.18.x,
 ``packages/sdk/openapi.json``). This is a thin typed wrapper over the v1
 REST endpoints the Omnigent OpenCode-native harness needs plus the SSE
 ``GET /event`` stream — not a full generated SDK. Unknown response fields
@@ -29,10 +29,11 @@ from omnigent.json_types import JsonObject as _JsonObject
 
 _logger = logging.getLogger(__name__)
 
-# Pinned OpenCode CLI/API version range. The source monorepo reports
-# 1.17.7; we accept 1.17.x and refuse 1.18+ until validated.
+# Supported OpenCode CLI/API version range. Accepts 1.17.7+ through the
+# entire 1.18.x line (validated against 1.18.x event/API shapes); refuses
+# 1.19+ until validated against that release.
 OPENCODE_MIN_VERSION = "1.17.7"
-OPENCODE_MAX_VERSION_EXCLUSIVE = "1.18.0"
+OPENCODE_MAX_VERSION_EXCLUSIVE = "1.19.0"
 
 _DEFAULT_TIMEOUT = httpx.Timeout(30.0, connect=10.0)
 
diff --git a/omnigent/opencode_native_forwarder.py b/omnigent/opencode_native_forwarder.py
index 399c5b79..dac93ef0 100644
--- a/omnigent/opencode_native_forwarder.py
+++ b/omnigent/opencode_native_forwarder.py
@@ -1043,8 +1043,8 @@ def opencode_tool_output_text(state: _JsonMapping) -> str:
 # resolves the method on the instance. Keys are OpenCode event ``type``
 # discriminators (see openapi.json Event* schemas).
 _HANDLERS: dict[str, Callable[[OpenCodeNativeForwarder, OpenCodeEvent], Awaitable[None]]] = {
-    # opencode 1.17.x is part-based: text/tool live on message PARTS, lifecycle
-    # on the message + session. (Verified against a real ``opencode serve``.)
+    # opencode 1.17.x–1.18.x is part-based: text/tool live on message PARTS,
+    # lifecycle on the message + session. (Verified against real ``opencode serve``.)
     "message.updated": OpenCodeNativeForwarder._on_message_updated,
     "message.part.updated": OpenCodeNativeForwarder._on_part_updated,
     # NB: ``message.part.delta`` (live token stream) is intentionally NOT
@@ -1066,7 +1066,7 @@ _HANDLERS: dict[str, Callable[[OpenCodeNativeForwarder, OpenCodeEvent], Awaitabl
     "session.compacted": OpenCodeNativeForwarder._on_compaction_ended,
     # Mirror a TUI model switch back to Omnigent (in-harness session-cmd sync).
     "session.next.model.switched": OpenCodeNativeForwarder._on_model_switched,
-    # Permission ask: 1.17.x emits ``permission.asked``; keep the ``v2`` spelling
+    # Permission ask: pre-1.18 emits ``permission.asked``; keep the ``v2`` spelling
     # too so a point-release rename still routes through the policy gate.
     "permission.asked": OpenCodeNativeForwarder._on_permission_asked,
     "permission.v2.asked": OpenCodeNativeForwarder._on_permission_asked,
diff --git a/tests/onboarding/test_harness_install.py b/tests/onboarding/test_harness_install.py
index 61b8a69c..7ccac100 100644
--- a/tests/onboarding/test_harness_install.py
+++ b/tests/onboarding/test_harness_install.py
@@ -1154,7 +1154,7 @@ def test_ui_setup_steps_generic_for_non_installable() -> None:
 @pytest.mark.parametrize(
     "key,min_version,max_version_exclusive",
     [
-        (hi.OPENCODE_KEY, "1.17.7", "1.18.0"),
+        (hi.OPENCODE_KEY, "1.17.7", "1.19.0"),
         (hi.CURSOR_KEY, "2026.06.02", None),
         (hi.KIMI_KEY, "0.7.0", None),
         (ANTHROPIC_FAMILY, "2.1.161", None),
@@ -1180,9 +1180,10 @@ def test_versioned_specs_declare_bounds(
     "version,expected",
     [
         ("1.17.6", False),  # below min
-        ("1.18.0", False),  # at max exclusive
+        ("1.19.0", False),  # at max exclusive
         ("2.0.0", False),  # above max
         ("1.17.8", True),  # inside range
+        ("1.18.16", True),  # inside range (1.18.x)
     ],
 )
 def test_harness_cli_installed_checks_version_for_versioned_specs(
@@ -1194,7 +1195,7 @@ def test_harness_cli_installed_checks_version_for_versioned_specs(
 
     def _run(argv: list[str], **k: object) -> subprocess.CompletedProcess[str]:
         if len(argv) >= 2 and argv[1] == "--version":
-            # OpenCode's supported range is [1.17.7, 1.18.0).
+            # OpenCode's supported range is [1.17.7, 1.19.0).
             return subprocess.CompletedProcess(
                 args=argv, returncode=0, stdout=f"{version}\n", stderr=""
             )
diff --git a/tests/test_opencode_native_app_server.py b/tests/test_opencode_native_app_server.py
index 397fef51..47c1ed90 100644
--- a/tests/test_opencode_native_app_server.py
+++ b/tests/test_opencode_native_app_server.py
@@ -31,9 +31,11 @@ def test_parse_opencode_version() -> None:
 def test_check_version_in_range() -> None:
     check_opencode_version("1.17.7")
     check_opencode_version("1.17.99")
+    check_opencode_version("1.18.0")
+    check_opencode_version("1.18.16")
 
 
-@pytest.mark.parametrize("version", ["1.16.0", "1.18.0", "2.0.0"])
+@pytest.mark.parametrize("version", ["1.16.0", "1.19.0", "2.0.0"])
 def test_check_version_out_of_range_raises(version: str) -> None:
     with pytest.raises(OpenCodeVersionError):
         check_opencode_version(version)
@@ -186,7 +188,7 @@ async def test_start_raises_on_unsupported_version_without_env(
     monkeypatch: pytest.MonkeyPatch, tmp_path: Path
 ) -> None:
     monkeypatch.setattr(appsrv.shutil, "which", lambda name: f"/usr/bin/{name}")
-    monkeypatch.setattr(appsrv, "resolve_opencode_version", lambda _path: "1.18.0")
+    monkeypatch.setattr(appsrv, "resolve_opencode_version", lambda _path: "1.19.0")
     monkeypatch.delenv("OMNIGENT_OPENCODE_SKIP_VERSION_CHECK", raising=False)
     server = OpenCodeNativeServer(
         bridge_dir=tmp_path,
@@ -214,7 +216,7 @@ async def test_start_skips_version_gate_when_env_set(
     monkeypatch: pytest.MonkeyPatch, tmp_path: Path
 ) -> None:
     monkeypatch.setattr(appsrv.shutil, "which", lambda name: f"/usr/bin/{name}")
-    monkeypatch.setattr(appsrv, "resolve_opencode_version", lambda _path: "1.18.0")
+    monkeypatch.setattr(appsrv, "resolve_opencode_version", lambda _path: "1.19.0")
     monkeypatch.setenv("OMNIGENT_OPENCODE_SKIP_VERSION_CHECK", "1")
     server = OpenCodeNativeServer(
         bridge_dir=tmp_path,
@@ -235,7 +237,7 @@ async def test_start_skips_version_gate_when_env_set(
     monkeypatch.setattr(appsrv.subprocess, "Popen", lambda argv, **kwargs: _FakeProc())
     monkeypatch.setattr(OpenCodeNativeServer, "_wait_until_ready", fake_wait)
     await server.start()
-    assert server.version == "1.18.0"
+    assert server.version == "1.19.0"
     assert server.process is not None