diff --git a/web/oss/src/components/pages/settings/Secrets/SecretProviderTable/index.tsx b/web/oss/src/components/pages/settings/Secrets/SecretProviderTable/index.tsx
index 728c41ff79..f7d1046119 100644
--- a/web/oss/src/components/pages/settings/Secrets/SecretProviderTable/index.tsx
+++ b/web/oss/src/components/pages/settings/Secrets/SecretProviderTable/index.tsx
@@ -203,7 +203,7 @@ const SecretProviderTable = ({type}: {type: "standard" | "custom"}) => {
                             size="small"
                             onClick={() => setIsConfigProviderOpen(true)}
                         >
-                            Custom Provider
+                            OpenAI-compatible endpoint
                         </Button>
                     ) : (
                         <Button
diff --git a/web/oss/tests/playwright/acceptance/settings/model-hub.ts b/web/oss/tests/playwright/acceptance/settings/model-hub.ts
index b0491f5221..4e4968058e 100644
--- a/web/oss/tests/playwright/acceptance/settings/model-hub.ts
+++ b/web/oss/tests/playwright/acceptance/settings/model-hub.ts
@@ -1,9 +1,3 @@
-import {test} from "@agenta/web-tests/tests/fixtures/base.fixture"
-
-import {expect} from "@agenta/web-tests/utils"
-import {expectAuthenticatedSession} from "../utils/auth"
-import {createScenarios} from "../utils/scenarios"
-import {buildAcceptanceTags} from "../utils/tags"
 import {
     TestCoverage,
     TestcaseType,
@@ -15,6 +9,12 @@ import {
     TestRoleType,
     TestSpeedType,
 } from "@agenta/web-tests/playwright/config/testTags"
+import {test} from "@agenta/web-tests/tests/fixtures/base.fixture"
+import {expect} from "@agenta/web-tests/utils"
+
+import {expectAuthenticatedSession} from "../utils/auth"
+import {createScenarios} from "../utils/scenarios"
+import {buildAcceptanceTags} from "../utils/tags"
 
 /**
  * E2E: Model Hub & API Keys Management
@@ -67,7 +67,7 @@ const modelHubTests = () => {
 
         await scenarios.then('the "Custom providers" table lists the "mock" provider', async () => {
             const customProvidersSection = page
-                .getByText("Custom Provider", {exact: true})
+                .getByText("OpenAI-compatible endpoint", {exact: true})
                 .locator("xpath=ancestor::section[1]")
                 .first()
             const providersTable = customProvidersSection.getByRole("table").first()
@@ -206,14 +206,14 @@ const modelHubTests = () => {
                 "the user creates a new custom provider via the drawer",
                 async () => {
                     const customProvidersSection = page
-                        .getByText("Custom Provider", {exact: true})
+                        .getByText("OpenAI-compatible endpoint", {exact: true})
                         .locator("xpath=ancestor::section[1]")
                         .first()
 
                     // The section's own label IS the trigger button now — "Create" was
-                    // renamed to "Custom Provider".
+                    // renamed to "OpenAI-compatible endpoint".
                     const createButton = customProvidersSection.getByRole("button", {
-                        name: "Custom Provider",
+                        name: "OpenAI-compatible endpoint",
                         exact: true,
                     })
                     await expect(createButton).toBeVisible({timeout: 15000})
@@ -225,7 +225,7 @@ const modelHubTests = () => {
                         timeout: 15000,
                     })
 
-                    // Select "Custom Provider" from the provider type dropdown
+                    // Select "OpenAI-compatible endpoint" from the provider type dropdown
                     const providerSelect = drawer.locator(".ant-select").first()
                     await expect(providerSelect).toBeVisible({timeout: 15000})
                     await providerSelect.click()
@@ -235,7 +235,7 @@ const modelHubTests = () => {
 
                     const optionTexts = (await options.allTextContents()).map((t) => t.trim())
                     const customProviderIndex = optionTexts.findIndex(
-                        (t) => t === "Custom Provider",
+                        (t) => t === "OpenAI-compatible endpoint",
                     )
 
                     // Click the target option directly — keyboard ArrowDown navigation is unreliable with AntD v5 selects
@@ -266,7 +266,7 @@ const modelHubTests = () => {
                 "the new custom provider row appears in the Custom providers table",
                 async () => {
                     const customProvidersSection = page
-                        .getByText("Custom Provider", {exact: true})
+                        .getByText("OpenAI-compatible endpoint", {exact: true})
                         .locator("xpath=ancestor::section[1]")
                         .first()
 
@@ -285,7 +285,7 @@ const modelHubTests = () => {
 
             await scenarios.when("the user deletes the newly created custom provider", async () => {
                 const customProvidersSection = page
-                    .getByText("Custom Provider", {exact: true})
+                    .getByText("OpenAI-compatible endpoint", {exact: true})
                     .locator("xpath=ancestor::section[1]")
                     .first()
 
@@ -306,7 +306,7 @@ const modelHubTests = () => {
 
             await scenarios.then("the deleted provider row is no longer visible", async () => {
                 const customProvidersSection = page
-                    .getByText("Custom Provider", {exact: true})
+                    .getByText("OpenAI-compatible endpoint", {exact: true})
                     .locator("xpath=ancestor::section[1]")
                     .first()
 
diff --git a/web/packages/agenta-entities/src/secret/core/types.ts b/web/packages/agenta-entities/src/secret/core/types.ts
index 41b6c47447..31c05b7a06 100644
--- a/web/packages/agenta-entities/src/secret/core/types.ts
+++ b/web/packages/agenta-entities/src/secret/core/types.ts
@@ -95,7 +95,9 @@ export const PROVIDER_LABELS: Record<string, string> = {
     bedrock: "AWS Bedrock",
     azure: "Azure OpenAI",
     minimax: "MiniMax",
-    custom: "Custom Provider",
+    // Stored value stays "custom"; only the user-visible label changes. The v1 custom deployment
+    // speaks the OpenAI Chat Completions dialect, so name it for what it connects to.
+    custom: "OpenAI-compatible endpoint",
 }
 
 export const PROVIDER_KINDS: Record<string, string> = {
diff --git a/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/agentTemplate/ProviderCredentialsSection.tsx b/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/agentTemplate/ProviderCredentialsSection.tsx
index 85224ef9ef..5f91c8c9ff 100644
--- a/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/agentTemplate/ProviderCredentialsSection.tsx
+++ b/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/agentTemplate/ProviderCredentialsSection.tsx
@@ -84,7 +84,7 @@ const CUSTOM_PROVIDER_ROWS: {kind: string; label: string}[] = [
     {kind: CustomProviderKind.Azure, label: "Azure OpenAI"},
     {kind: CustomProviderKind.Bedrock, label: "AWS Bedrock"},
     {kind: CustomProviderKind.VertexAi, label: "Vertex AI"},
-    {kind: CustomProviderKind.Custom, label: "Custom provider"},
+    {kind: CustomProviderKind.Custom, label: "OpenAI-compatible endpoint"},
 ]
 
 /** Family spellings that must compare equal across catalog names, vault env names, and titles. */
@@ -413,7 +413,7 @@ export function ProviderCredentialsSection({
                                         label={secret.name ?? "?"}
                                     />
                                 }
-                                label={secret.name ?? "Custom provider"}
+                                label={secret.name ?? "OpenAI-compatible endpoint"}
                                 trailing={
                                     <span className="h-1.5 w-1.5 shrink-0 rounded-full bg-[var(--ag-colorSuccess)]" />
                                 }
diff --git a/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/connectionUtils.ts b/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/connectionUtils.ts
index f3aa87f5e2..2630fd5ba8 100644
--- a/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/connectionUtils.ts
+++ b/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/connectionUtils.ts
@@ -432,6 +432,10 @@ export function vaultPickedProviderFamily(
     const family = familyFromModelId(modelId, capabilities)
     if (family) return family
     if (metadataProvider && !isDeploymentProviderKind(metadataProvider)) return metadataProvider
+    // The OpenAI-compatible (`custom`) deployment defaults to openai rather than deferring to the
+    // caller's prior (likely unrelated) provider fallback.
+    if (metadataProvider?.toLowerCase() === OPENAI_COMPATIBLE_KIND)
+        return OPENAI_COMPATIBLE_DEFAULT_FAMILY
     return null
 }
 
@@ -444,6 +448,13 @@ export function vaultPickedProviderFamily(
 // provider), so both must be recognized here or one flavor's connections silently vanish.
 const DEPLOYMENT_KINDS = new Set(["direct", "custom", "azure", "bedrock", "vertex_ai", "sagemaker"])
 
+// The `custom` deployment kind is the "OpenAI-compatible endpoint": its models are bare ids that
+// encode no vendor, and the v1 runner speaks the OpenAI Chat Completions dialect. So it resolves to
+// the `openai` provider family — used both to default a provider-less pick and to gate visibility
+// (a harness must reach openai, not just consume the `custom` deployment).
+const OPENAI_COMPATIBLE_KIND = "custom"
+const OPENAI_COMPATIBLE_DEFAULT_FAMILY = "openai"
+
 /**
  * Whether a custom_provider `kind` names a DEPLOYMENT surface (a hosting mechanism, not itself a
  * model family — e.g. "bedrock" hosts many families) rather than a plain provider family (e.g.
@@ -466,7 +477,15 @@ function harnessReachesCustomProviderKind(
 ): boolean {
     if (isDeploymentProviderKind(kind)) {
         const consumable = allowedDeployments(capabilities, harness)
-        return consumable.includes("*") || consumable.some((d) => d.toLowerCase() === kind)
+        const deploymentOk =
+            consumable.includes("*") || consumable.some((d) => d.toLowerCase() === kind)
+        if (!deploymentOk) return false
+        // An OpenAI-compatible (`custom`) deployment resolves to the openai provider family, so the
+        // harness must ALSO reach openai — otherwise a Claude-only-Anthropic harness that consumes
+        // `custom` would still be offered an OpenAI-compatible connection it cannot run.
+        if (kind === OPENAI_COMPATIBLE_KIND)
+            return harnessAllowsProvider(capabilities, harness, OPENAI_COMPATIBLE_DEFAULT_FAMILY)
+        return true
     }
     const providers = allowedProviders(capabilities, harness)
     return providers.includes("*") || providers.some((p) => p.toLowerCase() === kind)
diff --git a/web/packages/agenta-entity-ui/tests/unit/connectionUtils.test.ts b/web/packages/agenta-entity-ui/tests/unit/connectionUtils.test.ts
index b2986cffc1..4c6b727406 100644
--- a/web/packages/agenta-entity-ui/tests/unit/connectionUtils.test.ts
+++ b/web/packages/agenta-entity-ui/tests/unit/connectionUtils.test.ts
@@ -54,6 +54,15 @@ const CAPABILITIES: HarnessCapabilitiesMap = {
             },
         },
     },
+    // A Pi-family harness that consumes the OpenAI-compatible `custom` deployment AND reaches the
+    // openai provider family — the one combination an OpenAI-compatible connection may surface for.
+    pi_openai_compat: {
+        providers: ["openai"],
+        deployments: ["direct", "custom"],
+        connection_modes: ["agenta", "self_managed"],
+        model_selection: "provider/id",
+        models: {openai: ["gpt-5.5"]},
+    },
 }
 
 describe("connectionUtils: modelIdFromConfig", () => {
@@ -359,17 +368,57 @@ describe("connectionUtils: vaultModelGroups (custom_provider connections)", () =
         ).toEqual([])
     })
 
-    it("gates a deployment-kind connection (custom/bedrock/vertex_ai) against consumable deployments, not providers", () => {
-        // claude's capability entry declares "custom" as a consumable deployment.
+    it("gates a NON-custom deployment kind (bedrock) against consumable deployments only", () => {
+        // claude declares "bedrock" as a consumable deployment; its models encode their own family,
+        // so deployment consumption alone is the gate (no single-family provider check).
         expect(
             vaultModelGroups(
-                [{name: "my-gateway", provider: "custom", models: ["gpt-oss"]}],
+                [
+                    {
+                        name: "my-bedrock",
+                        provider: "bedrock",
+                        models: ["eu.anthropic.claude-haiku-4-5"],
+                    },
+                ],
                 CAPABILITIES,
                 "claude",
             ),
         ).toHaveLength(1)
-        // pi_core only consumes "direct" — a "custom" deployment connection stays hidden there
-        // (matches the runner: Pi ignores a resolved custom endpoint/base_url in v1).
+        // pi_core only consumes "direct" — a "bedrock" deployment connection stays hidden there.
+        expect(
+            vaultModelGroups(
+                [
+                    {
+                        name: "my-bedrock",
+                        provider: "bedrock",
+                        models: ["eu.anthropic.claude-haiku-4-5"],
+                    },
+                ],
+                CAPABILITIES,
+                "pi_core",
+            ),
+        ).toEqual([])
+    })
+
+    it("gates an OpenAI-compatible (custom) connection by BOTH consumable deployment and openai reach", () => {
+        // A harness that consumes `custom` AND reaches openai is offered it.
+        expect(
+            vaultModelGroups(
+                [{name: "my-gateway", provider: "custom", models: ["gpt-oss"]}],
+                CAPABILITIES,
+                "pi_openai_compat",
+            ),
+        ).toHaveLength(1)
+        // claude consumes `custom` but only reaches anthropic — the OpenAI-compatible connection is
+        // NOT offered (it resolves to the openai family Claude cannot run).
+        expect(
+            vaultModelGroups(
+                [{name: "my-gateway", provider: "custom", models: ["gpt-oss"]}],
+                CAPABILITIES,
+                "claude",
+            ),
+        ).toEqual([])
+        // pi_core does not consume `custom` at all — hidden regardless of provider reach.
         expect(
             vaultModelGroups(
                 [{name: "my-gateway", provider: "custom", models: ["gpt-oss"]}],
@@ -387,6 +436,14 @@ describe("connectionUtils: vaultModelGroups (custom_provider connections)", () =
                 "pi_core",
             ),
         ).toHaveLength(1)
+        // A custom connection is also offered under a missing map (both gates read permissive).
+        expect(
+            vaultModelGroups(
+                [{name: "my-gateway", provider: "custom", models: ["gpt-oss"]}],
+                null,
+                "pi_core",
+            ),
+        ).toHaveLength(1)
     })
 
     it("skips connections with no slug or no models", () => {
@@ -401,6 +458,41 @@ describe("connectionUtils: vaultModelGroups (custom_provider connections)", () =
             ),
         ).toEqual([])
     })
+
+    // Regression pins: the OpenAI-compatible feature adds a `custom`-only branch. Every flow that
+    // does NOT involve a custom connection must stay byte-identical to pre-feature behavior.
+    it("regression: an empty vault yields no groups on any harness (default picker state)", () => {
+        expect(vaultModelGroups([], CAPABILITIES, "pi_core")).toEqual([])
+        expect(vaultModelGroups([], CAPABILITIES, "claude")).toEqual([])
+        expect(vaultModelGroups(null, CAPABILITIES, "claude")).toEqual([])
+    })
+
+    it("regression: a Claude harness still sees its reachable (anthropic) vault connection unchanged", () => {
+        expect(
+            vaultModelGroups(
+                [{name: "my-anthropic", provider: "anthropic", models: ["a1"]}],
+                CAPABILITIES,
+                "claude",
+            ),
+        ).toHaveLength(1)
+    })
+
+    it("regression: a non-custom deployment connection to Claude is unchanged by the custom gate", () => {
+        // Claude consumes bedrock; the new openai-family check must NOT touch non-custom kinds.
+        expect(
+            vaultModelGroups(
+                [
+                    {
+                        name: "my-bedrock",
+                        provider: "bedrock",
+                        models: ["eu.anthropic.claude-haiku-4-5"],
+                    },
+                ],
+                CAPABILITIES,
+                "claude",
+            ),
+        ).toHaveLength(1)
+    })
 })
 
 describe("connectionUtils: isDeploymentProviderKind", () => {
@@ -451,4 +543,39 @@ describe("connectionUtils: vaultPickedProviderFamily (F1 — vault pick must per
     it("still resolves the family from metadata alone when the id is absent", () => {
         expect(vaultPickedProviderFamily(null, "openai", CAPABILITIES)).toBe("openai")
     })
+
+    it("defaults an OpenAI-compatible (custom) connection with a bare model id to openai", () => {
+        // The `custom` kind is a deployment surface (not itself a family), but the OpenAI-compatible
+        // endpoint speaks the OpenAI dialect — so a provider-less pick resolves to openai instead of
+        // deferring to the caller's prior-provider fallback (design Decision 8).
+        expect(vaultPickedProviderFamily("gpt-oss", "custom", CAPABILITIES)).toBe("openai")
+        expect(vaultPickedProviderFamily("qwen2.5-coder:7b", "custom", CAPABILITIES)).toBe("openai")
+    })
+
+    it("still prefers an explicit id-encoded family over the custom openai default", () => {
+        // If the id itself encodes a known family, that wins even for a custom connection.
+        expect(
+            vaultPickedProviderFamily("eu.anthropic.claude-haiku-4-5", "custom", CAPABILITIES),
+        ).toBe("anthropic")
+    })
+})
+
+describe("connectionUtils: custom pick persists openai family AND keeps the connection slug", () => {
+    // Mirrors what `useModelHarness.writeModel` composes for a picked OpenAI-compatible option: the
+    // resolved family (openai, from vaultPickedProviderFamily) plus the option's own connection slug
+    // (threaded through `metadata.connectionSlug`). Neither may be dropped.
+    it("composes a ModelRef with provider openai and the preserved agenta slug", () => {
+        const provider = vaultPickedProviderFamily("gpt-oss", "custom", CAPABILITIES)
+        const ref = composeModelValue({
+            modelId: "gpt-oss",
+            provider,
+            mode: "agenta",
+            slug: "my-gateway",
+        })
+        expect(ref).toEqual({
+            model: "gpt-oss",
+            provider: "openai",
+            connection: {mode: "agenta", slug: "my-gateway"},
+        })
+    })
 })
diff --git a/web/tests/tests/fixtures/base.fixture/providerHelpers/index.ts b/web/tests/tests/fixtures/base.fixture/providerHelpers/index.ts
index ea74814d0d..405b9b4ec0 100644
--- a/web/tests/tests/fixtures/base.fixture/providerHelpers/index.ts
+++ b/web/tests/tests/fixtures/base.fixture/providerHelpers/index.ts
@@ -146,7 +146,7 @@ async function waitForModelsPageReady(page: Page): Promise<void> {
                     .isVisible()
                     .catch(() => false)
                 const createButtonEnabled = await customProvidersSection
-                    .getByRole("button", {name: "Custom Provider"})
+                    .getByRole("button", {name: "OpenAI-compatible endpoint"})
                     .isEnabled()
                     .catch(() => false)
 
@@ -190,9 +190,9 @@ async function navigateToModels(page: Page, uiHelpers: UIHelpers): Promise<void>
 
 function getCustomProvidersSection(page: Page): Locator {
     // The custom-providers section no longer has a dedicated header label — its
-    // section-identifying text IS the "Custom Provider" trigger button now.
+    // section-identifying text IS the "OpenAI-compatible endpoint" trigger button now.
     return page
-        .getByText("Custom Provider", {exact: true})
+        .getByText("OpenAI-compatible endpoint", {exact: true})
         .locator("xpath=ancestor::section[1]")
         .first()
 }