diff --git a/src/core/observability.rs b/src/core/observability.rs
index 8f685f17d8..d2dd31799b 100644
--- a/src/core/observability.rs
+++ b/src/core/observability.rs
@@ -88,6 +88,22 @@ pub enum ExpectedErrorKind {
     /// 4xx body embedded, which would otherwise escape the
     /// [`is_backend_user_error_message`] 4xx-only matcher.
     ProviderUserState,
+    /// A user-configured custom cloud provider (`custom_openai` → DeepSeek
+    /// / OpenRouter / Moonshot / …) rejected the request because of the
+    /// user's **model / parameter configuration**: an OpenHuman abstract
+    /// tier alias leaked to a provider that only speaks its native ids
+    /// (#2079), an unknown / stale model pin (#2202), or a model-specific
+    /// temperature constraint (#2076 — Moonshot Kimi K2). The provider
+    /// HTTP layer (`providers::ops::api_error`) already demotes its own
+    /// per-attempt event; this catches the *re-report* when the same
+    /// error is raised again by `agent.run_single` /
+    /// `web_channel.run_chat_task` under `domain=agent` / `web_channel`.
+    /// Deterministic user-config state surfaced in the UI — Sentry has no
+    /// remediation path (OPENHUMAN-TAURI-WJ / -QW / -HB / -NH, ~273
+    /// events). See
+    /// [`crate::openhuman::inference::provider::is_provider_config_rejection_message`]
+    /// for the polarity contract and exact body shapes.
+    ProviderConfigRejection,
     LocalAiCapabilityUnavailable,
     BudgetExhausted,
     SessionExpired,
@@ -120,6 +136,15 @@ pub fn expected_error_kind(message: &str) -> Option<ExpectedErrorKind> {
     if is_backend_user_error_message(&lower) {
         return Some(ExpectedErrorKind::BackendUserError);
     }
+    // Provider config-rejection (unknown model / abstract tier leaked to a
+    // custom provider / model-specific temperature). Body-shape based and
+    // intrinsically scoped to third-party providers — the OpenHuman
+    // backend never emits these phrases. See the predicate's polarity
+    // contract. Drops OPENHUMAN-TAURI-WJ / -QW / -HB / -NH re-reports
+    // (#2079 / #2076 / #2202).
+    if crate::openhuman::inference::provider::is_provider_config_rejection_message(message) {
+        return Some(ExpectedErrorKind::ProviderConfigRejection);
+    }
     if is_local_ai_capability_unavailable_message(&lower) {
         return Some(ExpectedErrorKind::LocalAiCapabilityUnavailable);
     }
@@ -503,6 +528,26 @@ fn report_expected_message(kind: ExpectedErrorKind, message: &str, domain: &str,
                 "[observability] {domain}.{operation} skipped expected provider-user-state error: {message}"
             );
         }
+        ExpectedErrorKind::ProviderConfigRejection => {
+            // User-config state: a custom cloud provider rejected the
+            // request because of the user's model / parameter setup — an
+            // OpenHuman abstract tier alias leaked to a provider that only
+            // speaks its native ids (#2079), an unknown / stale model pin
+            // (#2202), or a model-specific temperature constraint (#2076,
+            // Moonshot Kimi K2). The provider HTTP layer already demoted
+            // its own per-attempt event; this is the re-report raised
+            // again by agent.run_single / web_channel.run_chat_task. The
+            // UI surfaces an actionable "fix your model/provider settings"
+            // error — Sentry has no remediation path
+            // (OPENHUMAN-TAURI-WJ / -QW / -HB / -NH).
+            tracing::info!(
+                domain = domain,
+                operation = operation,
+                kind = "provider_config_rejection",
+                error = %message,
+                "[observability] {domain}.{operation} skipped expected provider config-rejection error: {message}"
+            );
+        }
         ExpectedErrorKind::LocalAiCapabilityUnavailable => {
             // User-state condition: the local-AI service refused a
             // capability (vision summarization, vision asset download)
@@ -1497,6 +1542,57 @@ mod tests {
         );
     }
 
+    #[test]
+    fn classifies_provider_config_rejection() {
+        // #2079 — an OpenHuman abstract tier alias leaked to a custom
+        // provider; raised again by `agent.run_single` /
+        // `web_channel.run_chat_task` so it escapes the provider-layer
+        // demotion and reaches `report_error_or_expected` here.
+        assert_eq!(
+            expected_error_kind(
+                "agent.run_single failed: custom_openai API error (400 Bad Request): \
+                 The supported API model names are deepseek-v4-pro or deepseek-v4-flash, \
+                 but you passed reasoning-v1."
+            ),
+            Some(ExpectedErrorKind::ProviderConfigRejection)
+        );
+        // #2076 — Moonshot Kimi K2 temperature constraint.
+        assert_eq!(
+            expected_error_kind(
+                "custom_openai API error (400): invalid temperature: only 1 is allowed for this model"
+            ),
+            Some(ExpectedErrorKind::ProviderConfigRejection)
+        );
+        // #2202 — unknown / stale model pin (OpenAI-compatible body).
+        assert_eq!(
+            expected_error_kind(
+                "custom_openai API error (400): Model 'claude-opus-4-7' is not available. \
+                 Use GET /openai/v1/models to list available models."
+            ),
+            Some(ExpectedErrorKind::ProviderConfigRejection)
+        );
+    }
+
+    #[test]
+    fn does_not_classify_unrelated_provider_failures_as_config_rejection() {
+        // Inverted polarity / scope guard: a 5xx or a generic 4xx with no
+        // config-rejection body must still reach Sentry as actionable.
+        // (The OpenHuman backend never emits these phrases, so the
+        // message-level predicate is intrinsically custom-provider scoped;
+        // the HTTP-layer twin enforces the non-backend guard explicitly.)
+        assert_eq!(
+            expected_error_kind("custom_openai API error (500): internal server error"),
+            None
+        );
+        assert_eq!(
+            expected_error_kind(
+                "custom_openai API error (400 Bad Request): missing required field 'messages'"
+            ),
+            None,
+            "generic 4xx without a config-rejection body must NOT demote"
+        );
+    }
+
     #[test]
     fn unrelated_missing_required_fields_classifies_as_accepted_false_positive() {
         // Documents the breadth of the `"missing required fields"` arm —
@@ -2138,6 +2234,23 @@ mod tests {
             "provider_chat",
             &[("provider", "ollama")],
         );
+        // #2079 / #2076 / #2202 — exercises the expected_error_kind
+        // ProviderConfigRejection branch AND the report_expected_message
+        // skip-log arm (the agent/web-channel re-report demotion path).
+        report_error_or_expected(
+            "agent.run_single failed: custom_openai API error (400 Bad Request): \
+             The supported API model names are deepseek-v4-pro or deepseek-v4-flash, \
+             but you passed reasoning-v1.",
+            "agent",
+            "native_chat",
+            &[("provider", "custom_openai")],
+        );
+        report_error_or_expected(
+            "custom_openai API error (400): invalid temperature: only 1 is allowed for this model",
+            "web_channel",
+            "run_chat_task",
+            &[("provider", "custom_openai")],
+        );
     }
 
     fn event_with_message(msg: &str) -> sentry::protocol::Event<'static> {
diff --git a/src/openhuman/channels/providers/web.rs b/src/openhuman/channels/providers/web.rs
index 0ecdba1cec..b0be66866c 100644
--- a/src/openhuman/channels/providers/web.rs
+++ b/src/openhuman/channels/providers/web.rs
@@ -287,6 +287,23 @@ fn classify_inference_error(err: &str) -> (&'static str, String) {
                 err,
             ),
         )
+    } else if crate::openhuman::inference::provider::is_provider_config_rejection_message(err) {
+        // #2079 / #2076 / #2202: an OpenHuman abstract tier alias leaked to
+        // a custom provider, a stale model pin, or a model-specific
+        // temperature constraint. Checked BEFORE the generic
+        // model-unavailable arm so config-rejection bodies that also
+        // contain "model"/"does not exist"/"does not have access" get the
+        // specific "Settings → LLM" remediation instead of the generic
+        // copy. Shared predicate keeps this in lockstep with the
+        // Sentry-demotion classifier.
+        (
+            "model_unavailable",
+            with_provider_detail(
+                "Your AI provider rejected the request's model or temperature setting. \
+                 Check your model and routing in Settings → LLM.",
+                err,
+            ),
+        )
     } else if lower.contains("model")
         && (lower.contains("not found")
             || lower.contains("unavailable")
diff --git a/src/openhuman/channels/providers/web_tests.rs b/src/openhuman/channels/providers/web_tests.rs
index 9373d3f630..d2551eb0ad 100644
--- a/src/openhuman/channels/providers/web_tests.rs
+++ b/src/openhuman/channels/providers/web_tests.rs
@@ -161,16 +161,52 @@ fn extract_provider_error_detail_returns_none_for_transport_errors() {
 
 #[test]
 fn classify_inference_error_quotes_model_unavailable_detail() {
+    // A stale model pin (`model_not_found` / "does not exist or you do not
+    // have access") is the #2202 config-rejection class: it now resolves
+    // via the provider-config-rejection arm (ordered before the generic
+    // model-unavailable arm) and gets the actionable Settings remediation,
+    // while still classifying as `model_unavailable` and quoting the
+    // upstream detail.
     let raw = r#"custom_openai API error (404 Not Found): {"error":{"message":"The model `gpt-5.5` does not exist or you do not have access to it.","code":"model_not_found"}}"#;
     let (category, message) = classify_inference_error(raw);
     assert_eq!(category, "model_unavailable");
-    assert!(message.contains("Check your model settings"));
+    assert!(
+        message.contains("Settings → LLM"),
+        "config-rejection must give the actionable remediation: {message}"
+    );
     assert!(
         message.contains("gpt-5.5"),
         "should quote model name: {message}"
     );
 }
 
+#[test]
+fn classify_inference_error_surfaces_provider_config_rejection_actionably() {
+    // #2079 / #2076 / #2202: before this arm these fell through to the
+    // generic "inference" bucket and the user saw no actionable
+    // remediation. Each must now classify as `model_unavailable` with the
+    // "fix your model/routing" copy, and quote the upstream detail.
+    let cases = [
+        // #2079 — abstract tier alias leaked to a custom provider.
+        r#"custom_openai API error (400 Bad Request): {"error":{"message":"The supported API model names are deepseek-v4-pro or deepseek-v4-flash, but you passed reasoning-v1.","type":"invalid_request_error"}}"#,
+        // #2076 — Moonshot Kimi K2 only accepts temperature: 1.
+        r#"custom_openai API error (400): {"error":{"message":"invalid temperature: only 1 is allowed for this model","type":"invalid_request_error"}}"#,
+        // #2202 — unknown / stale model pin.
+        r#"custom_openai API error (400): {"error":{"message":"Model 'claude-opus-4-7' is not available. Use GET /openai/v1/models to list available models."}}"#,
+    ];
+    for raw in cases {
+        let (category, message) = classify_inference_error(raw);
+        assert_eq!(
+            category, "model_unavailable",
+            "config-rejection must classify as model_unavailable, not generic: {raw}"
+        );
+        assert!(
+            message.contains("Settings → LLM"),
+            "must give actionable remediation: {message}"
+        );
+    }
+}
+
 #[test]
 fn generic_error_copy_is_sanitized_and_has_discord_report_action() {
     let message = generic_inference_error_user_message();
diff --git a/src/openhuman/inference/provider/config_rejection.rs b/src/openhuman/inference/provider/config_rejection.rs
new file mode 100644
index 0000000000..542ef8723b
--- /dev/null
+++ b/src/openhuman/inference/provider/config_rejection.rs
@@ -0,0 +1,134 @@
+//! Classifier for **provider configuration-rejection** errors.
+//!
+//! When OpenHuman talks to a user-configured custom cloud endpoint
+//! (`custom_openai` → DeepSeek / OpenRouter / Moonshot / …) the upstream
+//! API rejects requests whose model id or sampling params it doesn't
+//! understand:
+//!
+//! - `"The supported API model names are deepseek-v4-pro or
+//!   deepseek-v4-flash, but you passed reasoning-v1."` (#2079 — an
+//!   OpenHuman abstract tier alias leaked to a provider that only speaks
+//!   its own native ids)
+//! - `"Model 'deepseek-v4-pro' is not available. Use GET
+//!   /openai/v1/models to list available models."` (#2202)
+//! - `"invalid temperature: only 1 is allowed for this model"` (#2076 —
+//!   Moonshot Kimi K2)
+//! - `"The model \`gpt-5.5\` does not exist or you do not have access to
+//!   it."` / `"model_not_found"` (stale model pin)
+//!
+//! These are **deterministic user-configuration state**, not bugs the
+//! maintainers can act on: the user pointed OpenHuman at a custom
+//! provider with a model / temperature that provider does not accept. The
+//! remediation is "fix the model or routing in Settings", which the UI
+//! surfaces. Yet every agent turn produces a fresh Sentry event
+//! (OPENHUMAN-TAURI-WJ / -QW / -HB / -NH — 88 + 146 + 39 events). This is
+//! the same class as budget-exhaustion ([`super::billing_error`]) and
+//! must be demoted from Sentry to an info log the same way.
+//!
+//! ## Provider-aware polarity (important)
+//!
+//! The phrases below are emitted by **third-party upstream APIs**
+//! (DeepSeek / OpenRouter / Moonshot). The OpenHuman hosted backend
+//! resolves tier aliases natively and never emits "supported API model
+//! names are deepseek-…" or "invalid temperature: only 1 is allowed" — so
+//! the phrase set is intrinsically scoped to custom providers. The
+//! HTTP-layer wrapper [`super::ops::is_provider_config_rejection_http`]
+//! additionally guards on `provider != openhuman_backend::PROVIDER_LABEL`
+//! so a model-rejection from our **own** backend (which would be a real
+//! regression we sent it a bad request) still reaches Sentry. The
+//! message-only predicate is consumed by
+//! [`crate::core::observability::expected_error_kind`] for the
+//! re-reported error that escapes the provider layer and is raised again
+//! by `agent.run_single` / `web_channel.run_chat_task`.
+//!
+//! Keep the list deliberately tight: a false positive demotes a real
+//! provider/backend bug to an info log.
+
+/// Returns true if a provider error body indicates the request was
+/// rejected because of the user's model / parameter **configuration**
+/// (unknown model id, abstract tier leaked to a custom provider,
+/// model-specific temperature constraint), as opposed to a transient
+/// failure or a server bug.
+///
+/// Case-insensitive substring match. See the module docs for the polarity
+/// contract and the OPENHUMAN-TAURI Sentry issues each phrase drops.
+pub fn is_provider_config_rejection_message(body: &str) -> bool {
+    const PHRASES: &[&str] = &[
+        // #2079 — an OpenHuman abstract tier alias (`reasoning-v1`,
+        // `chat-v1`, …) reached a custom provider that lists its own
+        // native ids back at us.
+        "supported api model names are",
+        // #2202 — OpenAI-compatible "unknown model" body. The
+        // `/openai/v1/models` remediation hint is the stable, unique
+        // anchor (the quoted model id varies per user).
+        "/openai/v1/models",
+        // OpenAI / OpenRouter stale-pin shape (`claude-opus-4-7`,
+        // `gpt-5.5`, …) — model removed or no access.
+        "does not exist or you do not have access",
+        "model_not_found",
+        // #2076 — Moonshot Kimi K2 only accepts `temperature: 1`.
+        "invalid temperature",
+        "only 1 is allowed for this model",
+        // Our own actionable error once a proper tier→model resolution
+        // is in place (keeps this classifier stable across that fix).
+        "is an abstract tier",
+    ];
+
+    let lower = body.to_ascii_lowercase();
+    PHRASES.iter().any(|phrase| lower.contains(phrase))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn detects_real_sentry_bodies() {
+        // The exact upstream bodies from OPENHUMAN-TAURI-WJ / -QW / -HB
+        // / -NH and the stale-pin family.
+        for body in [
+            "The supported API model names are deepseek-v4-pro or deepseek-v4-flash, but you passed reasoning-v1.",
+            "Model 'deepseek-v4-pro' is not available. Use GET /openai/v1/models to list available models.",
+            "Model 'claude-opus-4-7' is not available. Use GET /openai/v1/models to list available models.",
+            "invalid temperature: only 1 is allowed for this model",
+            "The model `gpt-5.5` does not exist or you do not have access to it.",
+            r#"{"error":{"message":"model not found","code":"model_not_found"}}"#,
+            "Model 'reasoning-v1' is an abstract tier — configure a concrete model for your custom provider",
+        ] {
+            assert!(
+                is_provider_config_rejection_message(body),
+                "{body:?} must classify as a provider config-rejection user-state"
+            );
+        }
+    }
+
+    #[test]
+    fn detection_is_case_insensitive() {
+        assert!(is_provider_config_rejection_message(
+            "INVALID TEMPERATURE: ONLY 1 IS ALLOWED FOR THIS MODEL"
+        ));
+        assert!(is_provider_config_rejection_message(
+            "The Supported API Model Names Are gpt-4o or gpt-4o-mini"
+        ));
+    }
+
+    #[test]
+    fn ignores_transient_and_server_and_unrelated() {
+        // Must NOT demote: transient/server failures and generic 4xx
+        // that carry no config-rejection signal — those stay Sentry
+        // actionable. (A real backend bug must not be silenced.)
+        for body in [
+            "Internal server error",
+            "503 Service Unavailable",
+            "Bad request: missing field",
+            "rate limit exceeded, retry after 1s",
+            "insufficient budget — add credits",
+            "",
+        ] {
+            assert!(
+                !is_provider_config_rejection_message(body),
+                "{body:?} must NOT classify as a provider config-rejection"
+            );
+        }
+    }
+}
diff --git a/src/openhuman/inference/provider/mod.rs b/src/openhuman/inference/provider/mod.rs
index e98b51659b..f47f71e2da 100644
--- a/src/openhuman/inference/provider/mod.rs
+++ b/src/openhuman/inference/provider/mod.rs
@@ -10,6 +10,7 @@ pub mod compatible_dump;
 pub mod compatible_parse;
 pub mod compatible_stream;
 pub mod compatible_types;
+pub mod config_rejection;
 pub mod factory;
 pub mod openhuman_backend;
 pub mod ops;
@@ -27,5 +28,6 @@ pub use traits::{
 };
 
 pub use billing_error::is_budget_exhausted_message;
+pub use config_rejection::is_provider_config_rejection_message;
 pub use factory::{create_chat_provider, provider_for_role};
 pub use ops::*;
diff --git a/src/openhuman/inference/provider/ops.rs b/src/openhuman/inference/provider/ops.rs
index f54bace279..b358cbfb5f 100644
--- a/src/openhuman/inference/provider/ops.rs
+++ b/src/openhuman/inference/provider/ops.rs
@@ -319,6 +319,47 @@ pub(super) fn log_budget_exhausted_http_400(
     );
 }
 
+/// Whether a provider non-2xx response is a deterministic
+/// **configuration-rejection** user-state error (unknown model id,
+/// abstract tier leaked to a custom provider, model-specific temperature
+/// constraint) that should be demoted from Sentry to an info log.
+///
+/// Provider-aware (inverted polarity vs. the 401/403 backend rule): the
+/// same body from the OpenHuman **backend** stays Sentry-actionable —
+/// that would mean we sent our own backend a bad request (a regression,
+/// e.g. #2079). Only client errors from a *custom / third-party*
+/// provider are user-config state. Restricted to the observed shapes
+/// (400 invalid-param / unknown-model, 404 model-does-not-exist, 422
+/// unprocessable); 408/429 are transient and handled separately.
+pub(super) fn is_provider_config_rejection_http(
+    status: reqwest::StatusCode,
+    provider: &str,
+    body: &str,
+) -> bool {
+    matches!(status.as_u16(), 400 | 404 | 422)
+        && provider != openhuman_backend::PROVIDER_LABEL
+        && super::is_provider_config_rejection_message(body)
+}
+
+pub(super) fn log_provider_config_rejection(
+    operation: &str,
+    provider: &str,
+    model: Option<&str>,
+    status: reqwest::StatusCode,
+) {
+    tracing::info!(
+        domain = "llm_provider",
+        operation = operation,
+        provider = provider,
+        model = model.unwrap_or(""),
+        status = status.as_u16(),
+        failure = "non_2xx",
+        kind = "provider_config_rejection",
+        "[llm_provider] {operation} provider config-rejection ({status}) — \
+         user model/param configuration, not reporting to Sentry"
+    );
+}
+
 /// Build a sanitized provider error from a failed HTTP response.
 ///
 /// Reports the failure to Sentry with `provider` and `status` tags so
@@ -337,6 +378,12 @@ pub(super) fn log_budget_exhausted_http_400(
 ///   override, halting downstream LLM work. 401/403 from **other** providers
 ///   (OpenAI, Anthropic, …) still go to Sentry — those mean a misconfigured
 ///   API key, which is actionable.
+/// - **Provider config-rejection** (4xx unknown-model / abstract-tier /
+///   model-specific temperature) from a **non-backend** provider — the
+///   user pointed a custom provider at a model/param it doesn't accept.
+///   Deterministic user-config state, surfaced in the UI; demoted to an
+///   info log (#2079 / #2076 / #2202). See
+///   [`is_provider_config_rejection_http`].
 pub async fn api_error(provider: &str, response: reqwest::Response) -> anyhow::Error {
     let status = response.status();
     let status_str = status.as_u16().to_string();
@@ -350,6 +397,7 @@ pub async fn api_error(provider: &str, response: reqwest::Response) -> anyhow::E
     let is_auth_failure = matches!(status.as_u16(), 401 | 403);
     let is_backend = provider == openhuman_backend::PROVIDER_LABEL;
     let is_budget_exhausted_user_state = is_budget_exhausted_http_400(status, &body);
+    let is_provider_config_rejection = is_provider_config_rejection_http(status, provider, &body);
 
     if is_auth_failure && is_backend {
         tracing::warn!(
@@ -372,6 +420,8 @@ pub async fn api_error(provider: &str, response: reqwest::Response) -> anyhow::E
         );
     } else if is_budget_exhausted_user_state {
         log_budget_exhausted_http_400("api_error", provider, None, status);
+    } else if is_provider_config_rejection {
+        log_provider_config_rejection("api_error", provider, None, status);
     } else if should_report_provider_http_failure(status) {
         crate::core::observability::report_error(
             message.as_str(),
@@ -823,6 +873,94 @@ mod tests {
         }
     }
 
+    // Exercises the real `is_provider_config_rejection_http` decision used
+    // by `api_error`, including the inverted provider-aware polarity.
+    mod provider_config_rejection_suppression {
+        use super::*;
+
+        // The exact #2079 Sentry body shape.
+        const TIER_LEAK_BODY: &str =
+            "The supported API model names are deepseek-v4-pro or deepseek-v4-flash, \
+             but you passed reasoning-v1.";
+        // #2076 Moonshot Kimi K2 temperature constraint.
+        const TEMP_BODY: &str = "invalid temperature: only 1 is allowed for this model";
+
+        #[test]
+        fn custom_provider_4xx_config_rejection_is_suppressed() {
+            assert!(is_provider_config_rejection_http(
+                reqwest::StatusCode::BAD_REQUEST,
+                "custom_openai",
+                TIER_LEAK_BODY,
+            ));
+            assert!(is_provider_config_rejection_http(
+                reqwest::StatusCode::BAD_REQUEST,
+                "custom_openai",
+                TEMP_BODY,
+            ));
+            // 404 "model does not exist" is the same user-config class.
+            assert!(is_provider_config_rejection_http(
+                reqwest::StatusCode::NOT_FOUND,
+                "custom_openai",
+                "The model `gpt-5.5` does not exist or you do not have access to it.",
+            ));
+        }
+
+        #[test]
+        fn openhuman_backend_same_body_is_not_suppressed() {
+            // Inverted polarity: a model-rejection from our OWN backend
+            // means we sent it a bad request — a real regression that must
+            // still reach Sentry. (Mirror of the 401/403 backend rule.)
+            assert!(!is_provider_config_rejection_http(
+                reqwest::StatusCode::BAD_REQUEST,
+                openhuman_backend::PROVIDER_LABEL,
+                TIER_LEAK_BODY,
+            ));
+        }
+
+        #[test]
+        fn server_error_is_not_suppressed() {
+            // A 5xx is a server bug, not user-config — keep reporting.
+            assert!(!is_provider_config_rejection_http(
+                reqwest::StatusCode::INTERNAL_SERVER_ERROR,
+                "custom_openai",
+                TIER_LEAK_BODY,
+            ));
+        }
+
+        #[test]
+        fn transient_429_is_not_suppressed_here() {
+            // 429 is transient; handled by should_report_provider_http_failure,
+            // not this classifier (must not be swallowed as user-config).
+            assert!(!is_provider_config_rejection_http(
+                reqwest::StatusCode::TOO_MANY_REQUESTS,
+                "custom_openai",
+                TIER_LEAK_BODY,
+            ));
+        }
+
+        #[test]
+        fn unrelated_4xx_body_is_not_suppressed() {
+            assert!(!is_provider_config_rejection_http(
+                reqwest::StatusCode::BAD_REQUEST,
+                "custom_openai",
+                "Bad request: missing required field 'messages'",
+            ));
+        }
+
+        #[test]
+        fn log_helper_runs_without_panicking() {
+            // Covers the demotion log path taken by `api_error` when a
+            // custom provider rejects the user's model/param config. No
+            // tracing subscriber in unit tests, so this is a pure smoke.
+            log_provider_config_rejection(
+                "api_error",
+                "custom_openai",
+                Some("reasoning-v1"),
+                reqwest::StatusCode::BAD_REQUEST,
+            );
+        }
+    }
+
     #[test]
     fn test_sanitize_api_error_utf8() {
         let input = "🦀".repeat(MAX_API_ERROR_CHARS + 10);