diff --git a/apps/daemon/internal/agent/claudesdk/local_test.go b/apps/daemon/internal/agent/claudesdk/local_test.go
index 2d6408645..4075aabd0 100644
--- a/apps/daemon/internal/agent/claudesdk/local_test.go
+++ b/apps/daemon/internal/agent/claudesdk/local_test.go
@@ -75,7 +75,7 @@ func TestWorkspaceProviderCredentialsReplaceAmbientSelection(t *testing.T) {
 	if !slices.Contains(env, "ANTHROPIC_AUTH_TOKEN=selected-secret") || slices.Contains(env, "ANTHROPIC_AUTH_TOKEN=selected-provider-fixture") {
 		t.Fatal("provider selection was not exclusive")
 	}
-	for _, value := range []any{nil, "secret", map[string]any{"protocol": "anthropic", "base_url": "http://provider.example", "api_key": "secret"}, map[string]any{"protocol": "anthropic", "base_url": "https://user:pass@provider.example", "api_key": "secret"}} {
+	for _, value := range []any{nil, "secret", map[string]any{"protocol": "anthropic", "base_url": "ftp://provider.example", "api_key": "secret"}, map[string]any{"protocol": "anthropic", "base_url": "https://user:pass@provider.example", "api_key": "secret"}} {
 		req.AgentOptions["model_provider"] = value
 		if _, _, err := prepare(config, req); err == nil || strings.Contains(err.Error(), "secret") {
 			t.Fatal("unsafe provider accepted or disclosed")
diff --git a/apps/daemon/internal/agent/mcode/model_provider_test.go b/apps/daemon/internal/agent/mcode/model_provider_test.go
index 715bf181c..4cc4eb833 100644
--- a/apps/daemon/internal/agent/mcode/model_provider_test.go
+++ b/apps/daemon/internal/agent/mcode/model_provider_test.go
@@ -50,7 +50,7 @@ func TestOptionsRejectInvalidProvider(t *testing.T) {
 	}{
 		{"unknown protocol", "protocol", "unknown"},
 		{"protocol alias", "protocol", "chat-completions"},
-		{"remote HTTP", "base_url", "http://provider.example/v1"},
+		{"unsupported scheme", "base_url", "ftp://provider.example/v1"},
 		{"empty key", "api_key", ""},
 		{"missing context", "context_window", 0},
 		{"missing output", "max_output_tokens", 0},
diff --git a/apps/web/e2e/fixture-console.mjs b/apps/web/e2e/fixture-console.mjs
index a3de5cafa..8f9147ad7 100644
--- a/apps/web/e2e/fixture-console.mjs
+++ b/apps/web/e2e/fixture-console.mjs
@@ -518,7 +518,8 @@ const HARNESS_PROVIDER = /^\/harnesses\/([^/]+)\/model-configuration$/;
 const PROVIDER_FIELDS = new Set(["protocol", "base_url", "api_key", "context_window", "max_output_tokens"]);
 /** Core's one message for a body that is not a complete provider; it never echoes a value. */
 const PROVIDER_SHAPE = "The body must be a complete model provider: protocol, base_url, api_key and optional nonnegative context_window and max_output_tokens.";
-const httpsBase = (value) => { try { const url = new URL(value); return url.protocol === "https:" && Boolean(url.hostname) && !url.username && !url.password && !url.search && !url.hash; } catch { return false; } };
+/** Core admits http and https on any host, without credentials, query or fragment. */
+const providerBaseUrl = (value) => { try { const url = new URL(value); const scheme = url.protocol === "https:" || url.protocol === "http:"; return scheme && Boolean(url.hostname) && !url.username && !url.password && !url.search && !url.hash; } catch { return false; } };
 /** An omitted limit, or a nonnegative integer that fits Core's int32. */
 const tokenLimit = (value) => value === undefined || (Number.isInteger(value) && value >= 0 && value <= 2 ** 31 - 1);
 const jsonKind = (value) => Array.isArray(value) ? "an array" : typeof value === "string" ? "a string" : typeof value === "boolean" ? "a boolean" : Number.isInteger(value) ? "an integer" : "a number";
@@ -527,7 +528,7 @@ const jsonKind = (value) => Array.isArray(value) ? "an array" : typeof value ===
 function providerProblem(harness, input) {
   if (Object.keys(input).some((key) => !PROVIDER_FIELDS.has(key)) || ["protocol", "base_url", "api_key"].some((key) => typeof input[key] !== "string") ||
     !tokenLimit(input.context_window) || !tokenLimit(input.max_output_tokens)) return PROVIDER_SHAPE;
-  if (!httpsBase(input.base_url)) return "model provider requires an HTTPS base_url without credentials, query or fragment";
+  if (!providerBaseUrl(input.base_url)) return "model provider requires an http or https base_url without credentials, query or fragment";
   if (!["anthropic", "responses", "chat_completions"].includes(input.protocol)) return "unsupported model provider protocol";
   if (!input.api_key.trim() || Buffer.byteLength(input.api_key) > 16384 || /[\0\r\n]/.test(input.api_key)) return "invalid model provider API key";
   if ((input.max_output_tokens ?? 0) > (input.context_window ?? 0)) return "invalid model token limits";
diff --git a/apps/web/src/features/system/ModelProviderDialog.tsx b/apps/web/src/features/system/ModelProviderDialog.tsx
index 3e555058e..b29d2190d 100644
--- a/apps/web/src/features/system/ModelProviderDialog.tsx
+++ b/apps/web/src/features/system/ModelProviderDialog.tsx
@@ -24,12 +24,12 @@ function tokenLimit(text: string): { value: number | undefined; problem: "whole"
   return number > INT32_MAX ? { value: undefined, problem: "large" } : { value: number, problem: null };
 }
 
-function isProviderUrl(value: string): boolean {
+export function isProviderUrl(value: string): boolean {
   try {
     const url = new URL(value);
-    const authority = /^https:\/\/([^/]+)/iu.exec(value)?.[1];
-    return authority !== undefined && url.protocol === "https:" && url.hostname !== "" && !authority.includes("@")
-      && !/[\\\s?#]/u.test(value);
+    const authority = /^https?:\/\/([^/]+)/iu.exec(value)?.[1];
+    return authority !== undefined && (url.protocol === "https:" || url.protocol === "http:") && url.hostname !== ""
+      && !authority.includes("@") && !/[\\\s?#]/u.test(value);
   } catch {
     return false;
   }
@@ -38,7 +38,7 @@ function isProviderUrl(value: string): boolean {
 /**
  * Sets or replaces one harness's model configuration. Non-secret fields start from the
  * current provider; the API key never does. The protocol describes the upstream
- * model provider. The form checks the HTTPS provider URL and whole-number
+ * model provider. The form checks the HTTP or HTTPS provider URL and whole-number
  * limits within Core's range, with max output no larger than the context window.
  * Core's typed rejection is shown beside its field, or beside the form
  * when no editable field applies. Enter saves; a save in flight blocks another.
diff --git a/apps/web/src/features/system/model-provider-dialog.test.ts b/apps/web/src/features/system/model-provider-dialog.test.ts
new file mode 100644
index 000000000..8fafc56c6
--- /dev/null
+++ b/apps/web/src/features/system/model-provider-dialog.test.ts
@@ -0,0 +1,26 @@
+import { describe, expect, it } from "vitest";
+import { isProviderUrl } from "./ModelProviderDialog";
+
+// The dialog must accept exactly what Core's admission rule accepts: an http or
+// https URL with a host and no credentials, query or fragment. It previously
+// rejected plain http, which blocked the form for an operator-chosen endpoint.
+describe("model provider base URL", () => {
+  it.each([
+    "http://192.168.20.15:3721",
+    "https://api.example.com/v1",
+    "http://localhost:7351",
+    "http://10.0.0.7:8080/v1",
+    "http://[::1]:8443/v1",
+  ])("accepts %s", (url) => expect(isProviderUrl(url)).toBe(true));
+
+  it.each([
+    "ftp://192.168.20.15:3721",
+    "http://user:pw@192.168.20.15:3721",
+    "http://192.168.20.15:3721/?key=secret",
+    "http://192.168.20.15:3721/#frag",
+    "http:///v1",
+    "http://host/ v1",
+    "not a url",
+    "",
+  ])("rejects %s", (url) => expect(isProviderUrl(url)).toBe(false));
+});
diff --git a/apps/web/src/i18n/locales/en/core-errors.ts b/apps/web/src/i18n/locales/en/core-errors.ts
index ba11e4086..7c1477b89 100644
--- a/apps/web/src/i18n/locales/en/core-errors.ts
+++ b/apps/web/src/i18n/locales/en/core-errors.ts
@@ -12,7 +12,7 @@ export const coreErrors = {
   "model_configuration_model_invalid": "Enter a model ID of at most 1024 UTF-8 bytes without control characters.",
   "harness_config_invalid": "Check the supported native fields and their values. The JSON object must be at most 16 KiB and cannot redefine Core-managed settings.",
   "invalid_model_provider": "Enter the complete model provider configuration.",
-  "model_provider_base_url_invalid": "Use an HTTPS URL without credentials, query parameters or a fragment.",
+  "model_provider_base_url_invalid": "Use an HTTP or HTTPS URL without credentials, query parameters or a fragment.",
   "model_provider_protocol_unsupported": "This protocol is not supported by the harness.",
   "protocols": "Allowed protocols: {{protocols}}.",
   "model_provider_api_key_invalid": "Enter a valid API key without control characters.",
diff --git a/apps/web/src/i18n/locales/en/system.ts b/apps/web/src/i18n/locales/en/system.ts
index 01539ccb9..0ac0cac45 100644
--- a/apps/web/src/i18n/locales/en/system.ts
+++ b/apps/web/src/i18n/locales/en/system.ts
@@ -79,7 +79,7 @@ export const system = {
       setTitle: "Set default model configuration for {{harness}}",
       replaceTitle: "Replace default model configuration for {{harness}}",
       modelName: "Used for new Sessions when the application does not specify a model. Enter an exact model ID accepted by this provider.",
-      baseUrlInvalid: "Enter an HTTPS URL with a hostname and no credentials, query or fragment, such as https://api.example.com/v1.",
+      baseUrlInvalid: "Enter an HTTP or HTTPS URL with a hostname and no credentials, query or fragment, such as http://192.168.20.15:3721.",
       apiKeyHelp: "Required every time. Core encrypts it and never shows it again.",
       contextHelp: "The model's context window, in tokens. Optional.",
       contextHelpRequired: "The model's context window, in tokens. This harness requires it.",
diff --git a/apps/web/src/i18n/locales/zh-CN/core-errors.ts b/apps/web/src/i18n/locales/zh-CN/core-errors.ts
index 4334ca3c1..42bd7adc8 100644
--- a/apps/web/src/i18n/locales/zh-CN/core-errors.ts
+++ b/apps/web/src/i18n/locales/zh-CN/core-errors.ts
@@ -12,7 +12,7 @@ export const coreErrors = {
   "model_configuration_model_invalid": "请输入模型 ID，最多 1024 个 UTF-8 字节，且不能包含控制字符。",
   "harness_config_invalid": "请检查支持的原生字段及其取值。JSON 对象不能超过 16 KiB，也不能重复定义 Core 管理的设置。",
   "invalid_model_provider": "请填写完整的模型服务配置。",
-  "model_provider_base_url_invalid": "请使用 HTTPS 地址，不要包含凭证、查询参数或片段。",
+  "model_provider_base_url_invalid": "请使用 HTTP 或 HTTPS 地址，地址不要包含凭证、查询参数或片段。",
   "model_provider_protocol_unsupported": "此执行引擎不支持该协议。",
   "protocols": "支持的协议：{{protocols}}。",
   "model_provider_api_key_invalid": "请输入有效的 API Key，不要包含控制字符。",
diff --git a/apps/web/src/i18n/locales/zh-CN/system.ts b/apps/web/src/i18n/locales/zh-CN/system.ts
index 072fd56c5..95877ab69 100644
--- a/apps/web/src/i18n/locales/zh-CN/system.ts
+++ b/apps/web/src/i18n/locales/zh-CN/system.ts
@@ -81,7 +81,7 @@ export const system: TranslationShape<typeof english> = {
       setTitle: "设置 {{harness}} 的默认模型配置",
       replaceTitle: "替换 {{harness}} 的默认模型配置",
       modelName: "应用未指定模型时，新会话使用此模型。请填写该服务接受的准确模型 ID。",
-      baseUrlInvalid: "请输入包含主机名、不含账号密码、查询参数或片段的 HTTPS URL，例如 https://api.example.com/v1。",
+      baseUrlInvalid: "请输入包含主机名、不含账号密码、查询参数或片段的 HTTP 或 HTTPS URL，例如 http://192.168.20.15:3721。",
       apiKeyHelp: "每次都必须填写。Core 会加密保存，之后不再显示。",
       contextHelp: "模型的上下文窗口，单位为 token。可选。",
       contextHelpRequired: "模型的上下文窗口，单位为 token。此 harness 必须填写。",
diff --git a/contracts/agents-api/core-errors.md b/contracts/agents-api/core-errors.md
index b8eddd89d..fdae254f7 100644
--- a/contracts/agents-api/core-errors.md
+++ b/contracts/agents-api/core-errors.md
@@ -58,7 +58,7 @@ Each code returns HTTP 400 with `type: "invalid_request_error"`. A missing, malf
 | `invalid_name` | `name` | `max_length`: 128 for Projects and nodes, 80 for Project keys | The name failed the resource's validator |
 | `invalid_node_capacity` | `max_active` or `max_retained` | `min`: 1, `max`: 1000000 | Capacity is invalid; retained capacity must also be at least active capacity |
 | `invalid_model_provider` | null | omitted | A complete model-provider bundle is required |
-| `model_provider_base_url_invalid` | `base_url` | omitted | Requires HTTPS without credentials, query or fragment |
+| `model_provider_base_url_invalid` | `base_url` | omitted | Requires HTTP or HTTPS, without credentials, query or fragment |
 | `model_provider_protocol_unsupported` | `protocol` | `harness` and `allowed_protocols`, from the build's adapter catalog | The protocol is unknown or unsupported by the selected Harness |
 | `model_provider_api_key_invalid` | `api_key` | `max_length`: 16384 | The key is empty, too long or contains a prohibited character |
 | `model_provider_token_limits_invalid` | `context_window` or `max_output_tokens` | omitted | Limits are invalid, or the Harness requires positive limits that are missing |
diff --git a/contracts/agents-api/model-execution.md b/contracts/agents-api/model-execution.md
index 5be0513f1..888074400 100644
--- a/contracts/agents-api/model-execution.md
+++ b/contracts/agents-api/model-execution.md
@@ -80,7 +80,7 @@ New hosted requests, and requests that omit the inline model, record caller inte
 ```
 
 - `protocol` names the upstream API (`anthropic`, `responses` or `chat_completions`), not an engine. The selected Harness must support it natively.
-- `base_url` uses HTTPS with a valid host, without credentials, query or fragment.
+- `base_url` uses HTTP or HTTPS with a valid host, without credentials, query or fragment. The scheme is the operator's choice: a self-hosted provider on another host may be plain HTTP.
 - `api_key` is nonempty, at most 16 KiB and contains no NUL, CR or LF.
 - `context_window` and `max_output_tokens` are optional nonnegative integers, with output no larger than context; both must be positive for MiniMax Code. Use the real model's limits.
 - `agent.model` is the exact provider model ID; a supplied value always replaces the deployment model.
diff --git a/contracts/agents-api/v1/model_execution.go b/contracts/agents-api/v1/model_execution.go
index d3c5f22da..084193824 100644
--- a/contracts/agents-api/v1/model_execution.go
+++ b/contracts/agents-api/v1/model_execution.go
@@ -42,7 +42,7 @@ func (p *ModelProviderInput) validate(registry harnessconfig.Registry) error {
 		return &ModelProviderError{Code: "invalid_model_provider", Param: "", message: "model_provider is required"}
 	}
 	if !validModelProviderBaseURL(p.BaseURL) {
-		return &ModelProviderError{Code: "model_provider_base_url_invalid", Param: "base_url", message: "model provider requires an HTTPS base_url without credentials, query or fragment"}
+		return &ModelProviderError{Code: "model_provider_base_url_invalid", Param: "base_url", message: "model provider requires an http or https base_url without credentials, query or fragment"}
 	}
 	if !registry.SupportsProtocol(p.Protocol) {
 		return &ModelProviderError{Code: "model_provider_protocol_unsupported", Param: "protocol", message: "unsupported model provider protocol"}
diff --git a/contracts/agents-api/v1/model_execution_test.go b/contracts/agents-api/v1/model_execution_test.go
index 8db6938ea..a082746b1 100644
--- a/contracts/agents-api/v1/model_execution_test.go
+++ b/contracts/agents-api/v1/model_execution_test.go
@@ -27,13 +27,16 @@ func TestModelExecutionValidation(t *testing.T) {
 			t.Fatalf("unsupported protocol or harness accepted: %s/%s", tc.protocol, tc.harness)
 		}
 	}
-	for _, url := range []string{"http://example.com", "https://user:pass@example.com", "https://example.com?key=secret", "https://example.com#secret", "https://",
+	for _, url := range []string{"ftp://example.com", "file:///etc/passwd", "example.com/v1", "//example.com/v1",
+		"https://user:pass@example.com", "https://example.com?key=secret", "https://example.com#secret", "https://", "http://",
 		"https://example.com:99999/v1", "https://example.com:0/v1", "https://xn--.test", "https://xn--a.test", "https://a..b", "https://999.1.1.1"} {
 		if (&ModelProviderInput{Protocol: "responses", BaseURL: url, APIKey: "secret"}).Validate() == nil {
 			t.Fatal("unsafe or unusable provider URL accepted", url)
 		}
 	}
-	for _, url := range []string{"https://example.com:8443/v1", "https://127.0.0.1/v1", "https://[::1]:8443/v1", "https://model_gateway.internal/v1", "https://bücher.example/v1"} {
+	for _, url := range []string{"https://example.com:8443/v1", "https://127.0.0.1/v1", "https://[::1]:8443/v1", "https://model_gateway.internal/v1", "https://bücher.example/v1",
+		"http://127.0.0.1:7351", "http://127.0.0.1:7351/v1", "http://localhost:8080/v1", "http://[::1]:8080", "http://LOCALHOST/v1",
+		"http://example.com/v1", "http://10.0.0.5:8080/v1", "http://192.168.1.10/v1", "http://[fd00::1]/v1", "http://model_gateway.internal/v1"} {
 		if err := (&ModelProviderInput{Protocol: "responses", BaseURL: url, APIKey: "secret"}).Validate(); err != nil {
 			t.Fatal("valid provider URL rejected", url, err)
 		}
diff --git a/contracts/agents-api/v1/model_provider_admission.go b/contracts/agents-api/v1/model_provider_admission.go
index fa91a1cc2..c573f923d 100644
--- a/contracts/agents-api/v1/model_provider_admission.go
+++ b/contracts/agents-api/v1/model_provider_admission.go
@@ -9,7 +9,14 @@ import (
 	"golang.org/x/net/idna"
 )
 
-const providerScheme = "https"
+// providerSchemes are the schemes a model provider base_url may use. The
+// operator chooses whether the endpoint is served over TLS; a self-hosted
+// provider on another host is as valid a target as a public one. Credentials,
+// query and fragment stay rejected either way.
+var providerSchemes = map[string]bool{
+	"https": true,
+	"http":  true,
+}
 
 // providerHost converts a domain as URL host parsing does (UTS #46 without
 // hyphen or STD3 restrictions), rejecting invalid labels such as bad punycode.
@@ -52,7 +59,10 @@ func ModelProviderRequired(environment string) bool {
 
 func validModelProviderBaseURL(base string) bool {
 	u, err := url.Parse(base)
-	return err == nil && u.Scheme == providerScheme && validModelProviderHost(u) && u.User == nil && u.RawQuery == "" && u.Fragment == "" && !strings.ContainsAny(base, "\x00\r\n")
+	if err != nil || u.User != nil || u.RawQuery != "" || u.Fragment != "" || !validModelProviderHost(u) || strings.ContainsAny(base, "\x00\r\n") {
+		return false
+	}
+	return providerSchemes[u.Scheme]
 }
 
 // validModelProviderHost requires a usable host: an IP address, or a domain
diff --git a/contracts/agents-api/v1/model_provider_error_test.go b/contracts/agents-api/v1/model_provider_error_test.go
index bab331fdf..4248dfcf3 100644
--- a/contracts/agents-api/v1/model_provider_error_test.go
+++ b/contracts/agents-api/v1/model_provider_error_test.go
@@ -11,8 +11,8 @@ func TestModelProviderErrorMessagesAndPrecedence(t *testing.T) {
 		name, harness, code, param, message string
 		change                              func(*ModelProviderInput)
 	}{
-		{"url first", "codex", "model_provider_base_url_invalid", "base_url", "model provider requires an HTTPS base_url without credentials, query or fragment", func(p *ModelProviderInput) {
-			p.BaseURL = "http://private.example"
+		{"url first", "codex", "model_provider_base_url_invalid", "base_url", "model provider requires an http or https base_url without credentials, query or fragment", func(p *ModelProviderInput) {
+			p.BaseURL = "ftp://private.example"
 			p.Protocol = "private"
 			p.APIKey = ""
 		}},
diff --git a/contracts/agents-api/zh/core-errors.md b/contracts/agents-api/zh/core-errors.md
index d90ac52b0..1756cbb61 100644
--- a/contracts/agents-api/zh/core-errors.md
+++ b/contracts/agents-api/zh/core-errors.md
@@ -60,7 +60,7 @@ Web 的控制台服务器在 `/core` 路径上发生自身故障时使用此封
 | `invalid_name` | `name` | `max_length`：Projects 和节点为 128，Project 键为 80 | 名称未通过相应资源的验证器 |
 | `invalid_node_capacity` | `max_active` 或 `max_retained` | `min`：1，`max`：1000000 | 容量无效；保留容量还必须至少等于活动容量 |
 | `invalid_model_provider` | null | 省略 | 必须提供完整的模型提供商配置包 |
-| `model_provider_base_url_invalid` | `base_url` | 省略 | 必须使用 HTTPS，且不得包含凭据、查询或片段 |
+| `model_provider_base_url_invalid` | `base_url` | 省略 | 必须使用 HTTP 或 HTTPS，且不得包含凭据、查询或片段 |
 | `model_provider_protocol_unsupported` | `protocol` | `harness` 和 `allowed_protocols`，来自该构建的适配器目录 | 协议未知，或所选 Harness 不支持该协议 |
 | `model_provider_api_key_invalid` | `api_key` | `max_length`：16384 | 密钥为空、过长或包含禁止字符 |
 | `model_provider_token_limits_invalid` | `context_window` 或 `max_output_tokens` | 省略 | 限制无效，或 Harness 要求的正数限制缺失 |
diff --git a/contracts/agents-api/zh/model-execution.md b/contracts/agents-api/zh/model-execution.md
index 0b29d25a3..8738df785 100644
--- a/contracts/agents-api/zh/model-execution.md
+++ b/contracts/agents-api/zh/model-execution.md
@@ -82,7 +82,7 @@ Core 从同一个数据库快照读取 Agent 配置和加密配置包；显式
 ```
 
 - `protocol` 指定上游 API（`anthropic`、`responses` 或 `chat_completions`），而不是引擎。所选 Harness 必须原生支持它。
-- `base_url` 使用 HTTPS 和有效主机名，且不得包含凭据、查询参数或片段。
+- `base_url` 使用 HTTP 或 HTTPS 和有效主机名，且不得包含凭据、查询参数或片段。scheme 由管理员选择：部署在其他主机上的自建 provider 也可以使用明文 HTTP。
 - `api_key` 不得为空，最长为 16 KiB，并且不得包含 NUL、CR 或 LF。
 - `context_window` 和 `max_output_tokens` 是可选的非负整数，输出限制不得大于上下文限制；对于 MiniMax Code，两者都必须为正数。请使用真实模型的限制。
 - `agent.model` 是准确的提供商模型 ID；只要提供该值，就始终会替换部署模型。
diff --git a/internal/modelprovider/config.go b/internal/modelprovider/config.go
index 386277d8f..259287a61 100644
--- a/internal/modelprovider/config.go
+++ b/internal/modelprovider/config.go
@@ -5,7 +5,6 @@ import (
 	"bytes"
 	"encoding/json"
 	"errors"
-	"net"
 	"net/url"
 	"strings"
 )
@@ -65,9 +64,9 @@ func (p Provider) Validate() error {
 	if err != nil || u.Hostname() == "" || u.User != nil || u.RawQuery != "" || u.Fragment != "" || strings.ContainsAny(p.BaseURL, "\x00\r\n") {
 		return ErrConfiguration
 	}
-	// Remote providers require HTTPS. Runtime-local providers may use loopback
-	// HTTP; Core retains stricter public provider admission.
-	if u.Scheme != "https" && !(u.Scheme == "http" && net.ParseIP(u.Hostname()).IsLoopback()) {
+	// The scheme carries no admission decision here: an operator may point a
+	// Harness at a plain-HTTP endpoint, including one on another host.
+	if u.Scheme != "https" && u.Scheme != "http" {
 		return ErrConfiguration
 	}
 	if strings.TrimSpace(p.APIKey) == "" || len(p.APIKey) > 16384 || strings.ContainsAny(p.APIKey, "\x00\r\n") {
diff --git a/internal/modelprovider/config_test.go b/internal/modelprovider/config_test.go
index 8b6312608..5b5b881ff 100644
--- a/internal/modelprovider/config_test.go
+++ b/internal/modelprovider/config_test.go
@@ -25,7 +25,7 @@ func TestParseProviderValidatesFrozenBundle(t *testing.T) {
 		{"unknown field", "native_options", map[string]any{}}, {"alias", "protocol", "openai"},
 		{"missing key", "api_key", ""}, {"newline key", "api_key", "fixture\nkey"},
 		{"URL credentials", "base_url", "https://user:secret@model.example/v1"},
-		{"remote HTTP", "base_url", "http://model.example/v1"},
+		{"unsupported scheme", "base_url", "ftp://model.example/v1"},
 		{"query", "base_url", "https://model.example/v1?key=secret"},
 		{"fragment", "base_url", "https://model.example/v1#secret"},
 		{"negative limit", "context_window", -1}, {"excess output", "max_output_tokens", 64001},
diff --git a/packages/agents-client/src/admin-client.test.ts b/packages/agents-client/src/admin-client.test.ts
index 5089dfdff..d6531f9d2 100644
--- a/packages/agents-client/src/admin-client.test.ts
+++ b/packages/agents-client/src/admin-client.test.ts
@@ -165,7 +165,7 @@ describe("AdminClient transport boundary", () => {
     const input = { model: "test-model", harness_config: { model_reasoning_effort: "high" }, model_provider: { protocol: "responses", base_url: "https://model.example/v1", api_key: "write-only", context_window: 200000, max_output_tokens: 8000 } } as const;
     expect(await client.setHarnessModelConfiguration("codex", input)).toEqual(provider);
     expect(JSON.parse(fetch.mock.calls[0]![1]!.body as string)).toEqual(input);
-    for (const unsafe of [{ ...provider, api_key: "leak" }, { ...provider, harness: "mcode" }, { ...provider, model_provider: { ...provider.model_provider, api_key_configured: false } }, { ...provider, model_provider: { ...provider.model_provider, base_url: "http://model.example/v1" } }, { ...provider, model_provider: { ...provider.model_provider, api_key: "leak" } }, { ...provider, model: "" }, { ...provider, harness_config: [] }, { ...provider, extra: 1 }]) {
+    for (const unsafe of [{ ...provider, api_key: "leak" }, { ...provider, harness: "mcode" }, { ...provider, model_provider: { ...provider.model_provider, api_key_configured: false } }, { ...provider, model_provider: { ...provider.model_provider, base_url: "https://user:pw@model.example/v1" } }, { ...provider, model_provider: { ...provider.model_provider, api_key: "leak" } }, { ...provider, model: "" }, { ...provider, harness_config: [] }, { ...provider, extra: 1 }]) {
       await expect(clientWith(unsafe).client.retrieveHarnessModelConfiguration("codex")).rejects.toMatchObject({ code: "invalid_admin_response" });
     }
     for (const unsafe of [{ ...harnesses, data: [{ ...harnesses.data[1], model_configuration: { ...provider, api_key: "leak" } }] }, { ...harnesses, data: [harnesses.data[1], harnesses.data[1]] }, { data: harnesses.data }]) {
@@ -242,7 +242,7 @@ describe("AdminClient response contracts", () => {
     // Core once accepted hosts and ports that URL parsing rejects; one must not fail the list.
     const stored = ["https://p.test:99999/v1", "https://xn--.test", "https://[::1]:8443/v1", "HTTPS://p.test/v1?"].map((url, index) => withURL(url, `agent-${index}`));
     expect((await clientWith(page(stored)).client.listAgents(projectId)).data).toEqual(stored);
-    for (const url of ["http://p.test", "https://user:pw@p.test", "https://p.test/?key=secret", "https://p.test/#secret", "https://:443/v1"]) {
+    for (const url of ["https://user:pw@p.test", "https://p.test/?key=secret", "https://p.test/#secret", "https://:443/v1", "ftp://p.test"]) {
       await expect(clientWith(page([withURL(url)])).client.listAgents(projectId)).rejects.toBeInstanceOf(AgentCoreError);
     }
   });
diff --git a/packages/agents-client/src/execution-configuration-projection.ts b/packages/agents-client/src/execution-configuration-projection.ts
index 5ae4c5000..4be8afcd9 100644
--- a/packages/agents-client/src/execution-configuration-projection.ts
+++ b/packages/agents-client/src/execution-configuration-projection.ts
@@ -14,12 +14,12 @@ function selection(value: unknown, invalid: Invalid): SessionExecutionConfigurat
 }
 
 // Splits an absolute URL as RFC 3986 appendix B does, without parsing its host.
-const baseURLPattern = /^https:\/\/([^/?#]*)[^?#]*(?:\?([^#]*))?(?:#([\s\S]*))?$/iu;
+const baseURLPattern = /^https?:\/\/([^/?#]*)[^?#]*(?:\?([^#]*))?(?:#([\s\S]*))?$/iu;
 
 /**
- * Checks a stored base URL no more strictly than Core's write rule: HTTPS with a
- * host and no credentials, query or fragment. Host syntax is Core's to enforce;
- * a value an earlier Core accepted must not fail a whole list.
+ * Checks a stored base URL no more strictly than Core's write rule: an HTTP or
+ * HTTPS URL with a host and no credentials, query or fragment. Host syntax is
+ * Core's to enforce; a value an earlier Core accepted must not fail a whole list.
  */
 function safeBaseURL(value: string): boolean {
   const match = baseURLPattern.exec(value);
diff --git a/packages/agents-client/src/execution-configuration.test.ts b/packages/agents-client/src/execution-configuration.test.ts
index c3938f2f9..6a332b679 100644
--- a/packages/agents-client/src/execution-configuration.test.ts
+++ b/packages/agents-client/src/execution-configuration.test.ts
@@ -37,6 +37,12 @@ describe("frozen execution configuration", () => {
       expect(await clientReturning(value).retrieveSessionExecutionConfiguration(projectId, id)).toEqual(value);
     }
   });
+  it.each(["http://model.example/v1", "https://model.example/v1", "http://192.168.20.15:3721"])(
+    "accepts the operator-chosen provider scheme %s", async (baseURL) => {
+      const value = structuredClone(snapshot);
+      value.model_provider.configuration!.base_url = baseURL;
+      expect(await clientReturning(value).retrieveSessionExecutionConfiguration(projectId, id)).toEqual(value);
+    });
   it.each([
     { status: "redacted", source: "deployment", configuration: null },
     { status: "available", source: "deployment", configuration: { protocol: "responses", base_url: "https://deployment.example/v1", api_key_configured: true } },
diff --git a/services/core/internal/api/core_model_provider_validation_test.go b/services/core/internal/api/core_model_provider_validation_test.go
index f4d01ac45..92844ce93 100644
--- a/services/core/internal/api/core_model_provider_validation_test.go
+++ b/services/core/internal/api/core_model_provider_validation_test.go
@@ -49,8 +49,8 @@ func TestCoreModelProviderValidationFields(t *testing.T) {
 		details                          map[string]any
 	}{
 		{"bundle", "codex", `{"api_key":"private-key"}`, "invalid_model_provider", "", nil},
-		{"negative shape", "codex", `{"protocol":"responses","base_url":"http://private-url","api_key":"private-key","context_window":-1}`, "invalid_model_provider", "", nil},
-		{"url first", "codex", `{"protocol":"private-protocol","base_url":"http://private-url","api_key":"private-key"}`, "model_provider_base_url_invalid", "base_url", nil},
+		{"negative shape", "codex", `{"protocol":"responses","base_url":"https://example.test","api_key":"private-key","context_window":-1}`, "invalid_model_provider", "", nil},
+		{"url first", "codex", `{"protocol":"private-protocol","base_url":"ftp://private-url.example","api_key":"private-key"}`, "model_provider_base_url_invalid", "base_url", nil},
 		{"protocol", "codex", `{"protocol":"private-protocol","base_url":"https://example.test","api_key":"private-key"}`, "model_provider_protocol_unsupported", "protocol", map[string]any{"harness": "codex", "allowed_protocols": []any{"responses"}}},
 		{"key", "codex", `{"protocol":"responses","base_url":"https://example.test","api_key":"private-key\n"}`, "model_provider_api_key_invalid", "api_key", map[string]any{"max_length": float64(16384)}},
 		{"output", "codex", `{"protocol":"responses","base_url":"https://example.test","api_key":"private-key","context_window":1,"max_output_tokens":2}`, "model_provider_token_limits_invalid", "max_output_tokens", nil},
diff --git a/services/core/internal/api/model_provider_public_validation_test.go b/services/core/internal/api/model_provider_public_validation_test.go
index e334d368b..b4ac94979 100644
--- a/services/core/internal/api/model_provider_public_validation_test.go
+++ b/services/core/internal/api/model_provider_public_validation_test.go
@@ -7,7 +7,7 @@ import (
 
 func TestModelProviderPublicValidation(t *testing.T) {
 	for _, tc := range []struct{ name, provider string }{
-		{"url", `{"protocol":"responses","base_url":"http://private-url.example","api_key":"private-key"}`},
+		{"url", `{"protocol":"responses","base_url":"ftp://private-url.example","api_key":"private-key"}`},
 		{"protocol", `{"protocol":"private-protocol","base_url":"https://example.test","api_key":"private-key"}`},
 		{"key", `{"protocol":"responses","base_url":"https://example.test","api_key":""}`},
 		{"limits", `{"protocol":"responses","base_url":"https://example.test","api_key":"private-key","context_window":1,"max_output_tokens":2}`},
@@ -17,7 +17,7 @@ func TestModelProviderPublicValidation(t *testing.T) {
 			body := `{"agent":{"model":"fixture"},"environment":{"type":"openai_hosted"},"input":"hello","x_agents_core":{"model_provider":` + tc.provider + `}}`
 			out := credentialRequest(h, http.MethodPost, "/v1/agents/sessions", body)
 			messages := map[string]string{
-				"url":      "model provider requires an HTTPS base_url without credentials, query or fragment",
+				"url":      "model provider requires an http or https base_url without credentials, query or fragment",
 				"protocol": "unsupported model provider protocol", "key": "invalid model provider API key",
 				"limits": "invalid model token limits",
 			}
diff --git a/services/core/internal/api/saved_provider_test.go b/services/core/internal/api/saved_provider_test.go
index 5624721c0..b36fdbae8 100644
--- a/services/core/internal/api/saved_provider_test.go
+++ b/services/core/internal/api/saved_provider_test.go
@@ -134,7 +134,7 @@ func TestSavedProviderInvalidInput(t *testing.T) {
 		`{"model_provider":{"protocol":"responses","base_url":"https://example.test","api_key":"saved-provider-secret","api_key_configured":true}}`,
 		`{"model_provider":{"protocol":"responses","base_url":"https://example.test","api_key":"saved-provider-secret","context_window":null}}`,
 		`{"model_provider":{"protocol":"responses","base_url":"https://example.test","api_key":null}}`,
-		`{"model_provider":{"protocol":"responses","base_url":"http://example.test","api_key":"saved-provider-secret"}}`,
+		`{"model_provider":{"protocol":"responses","base_url":"ftp://example.test","api_key":"saved-provider-secret"}}`,
 		`{"model_provider":{"protocol":"responses","base_url":"https://user:saved-provider-secret@example.test","api_key":"saved-provider-secret"}}`,
 		`{"model_provider":{"protocol":"responses","base_url":"https://example.test","api_key":"saved-provider-secret","API_KEY":"secret"}}`,
 		`{"model_provider":{"protocol":"responses","base_url":"https://example.test","api_key":"saved-provider-secret","api_key":"other"}}`,