diff --git a/CHANGELOG.md b/CHANGELOG.md
index 346995be..41c20b9d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- OpenCode provider key lookup now honors the shared `OPENCODE_API_KEY` fallback for both Zen and Go runtime paths, matching model-picker detection when provider-specific keys are absent (#3145).
+
 ## [v0.51.165] — 2026-05-30 — Release EK (stage-batch47 — stop EventSource reconnect storm on long-lived SSE streams)
 
 ### Fixed
diff --git a/api/providers.py b/api/providers.py
index 200000d5..77b9c718 100644
--- a/api/providers.py
+++ b/api/providers.py
@@ -682,6 +682,12 @@ _PROVIDER_ENV_VAR_ALIASES: dict[str, tuple[str, ...]] = {
     # #1500 — agent runtime reads LM_API_KEY (canonical), but WebUI builds
     # ≤ v0.50.272 wrote LMSTUDIO_API_KEY into .env.  Keep reading both.
     "lmstudio": ("LMSTUDIO_API_KEY",),
+    # #3145 — provider detection treats OPENCODE_API_KEY as enabling both
+    # OpenCode Zen and OpenCode Go. The runtime-facing lookup must read the same
+    # shared bridge key after the provider-specific slot, otherwise Settings can
+    # show the groups as configured while chat fails the no-key path.
+    "opencode-zen": ("OPENCODE_API_KEY",),
+    "opencode-go": ("OPENCODE_API_KEY",),
 }
 
 # Providers that use OAuth or token flows — their credentials are managed
diff --git a/tests/test_issue3145_opencode_shared_runtime_key.py b/tests/test_issue3145_opencode_shared_runtime_key.py
new file mode 100644
index 00000000..34875cdb
--- /dev/null
+++ b/tests/test_issue3145_opencode_shared_runtime_key.py
@@ -0,0 +1,56 @@
+"""Regression tests for shared OpenCode API key runtime lookup (#3145)."""
+
+import pytest
+
+
+@pytest.mark.parametrize("provider_id", ["opencode-zen", "opencode-go"])
+def test_shared_opencode_api_key_resolves_for_runtime(monkeypatch, tmp_path, provider_id):
+    """Runtime-facing key lookup should honor OPENCODE_API_KEY for both groups."""
+    import api.providers as providers
+
+    hermes_home = tmp_path / "hermes-home"
+    hermes_home.mkdir()
+    (hermes_home / ".env").write_text("OPENCODE_API_KEY=shared-opencode-key\n", encoding="utf-8")
+
+    monkeypatch.setattr(providers, "_get_hermes_home", lambda: hermes_home)
+    monkeypatch.delenv("OPENCODE_ZEN_API_KEY", raising=False)
+    monkeypatch.delenv("OPENCODE_GO_API_KEY", raising=False)
+    monkeypatch.delenv("OPENCODE_API_KEY", raising=False)
+
+    assert providers._provider_has_key(provider_id) is True
+    assert providers._get_provider_api_key(provider_id) == "shared-opencode-key"
+
+
+@pytest.mark.parametrize("provider_id", ["opencode-zen", "opencode-go"])
+def test_shared_opencode_api_key_resolves_from_process_env(monkeypatch, tmp_path, provider_id):
+    """The shared env var should work even when no .env file exists."""
+    import api.providers as providers
+
+    monkeypatch.setattr(providers, "_get_hermes_home", lambda: tmp_path / "missing-home")
+    monkeypatch.delenv("OPENCODE_ZEN_API_KEY", raising=False)
+    monkeypatch.delenv("OPENCODE_GO_API_KEY", raising=False)
+    monkeypatch.setenv("OPENCODE_API_KEY", "shared-env-opencode-key")
+
+    assert providers._provider_has_key(provider_id) is True
+    assert providers._get_provider_api_key(provider_id) == "shared-env-opencode-key"
+
+
+def test_provider_specific_opencode_key_still_wins_over_shared(monkeypatch, tmp_path):
+    """Provider-specific env vars keep precedence over the shared fallback."""
+    import api.providers as providers
+
+    hermes_home = tmp_path / "hermes-home"
+    hermes_home.mkdir()
+    (hermes_home / ".env").write_text(
+        "OPENCODE_API_KEY=shared-opencode-key\n"
+        "OPENCODE_ZEN_API_KEY=zen-specific-key\n",
+        encoding="utf-8",
+    )
+
+    monkeypatch.setattr(providers, "_get_hermes_home", lambda: hermes_home)
+    monkeypatch.delenv("OPENCODE_API_KEY", raising=False)
+    monkeypatch.delenv("OPENCODE_ZEN_API_KEY", raising=False)
+    monkeypatch.delenv("OPENCODE_GO_API_KEY", raising=False)
+
+    assert providers._get_provider_api_key("opencode-zen") == "zen-specific-key"
+    assert providers._get_provider_api_key("opencode-go") == "shared-opencode-key"