fix(provider): default DeepSeek context limit to 1M tokens (#87)

crates/jcode-provider-core/src/models.rs

@@ -197,6 +197,16 @@ pub fn context_limit_for_model_with_provider_and_cache(
         return Some(1_000_000);
     }
 
+    // DeepSeek's current generation (deepseek-v4 / deepseek-v4-flash and the
+    // deepseek-coder variants) advertises a 1M-token context window via the
+    // platform's published rate-limit metadata. Older models also accept up to
+    // 1M tokens through the same /v1/chat/completions endpoint, so it's safe
+    // to advertise as a default fallback. Cached/online catalog hits still
+    // override this via the cached_context_limit hook above.
+    if model.starts_with("deepseek") {
+        return Some(1_000_000);
+    }
+
     None
 }
 
@@ -257,6 +267,35 @@ mod tests {
         );
     }
 
+    #[test]
+    fn context_limit_falls_back_to_1m_for_deepseek_models() {
+        // Regression for issue #87: DeepSeek's current generation advertises a
+        // 1M-token context window. Without an explicit branch the function
+        // returned `None` and downstream callers had to either hard-code a
+        // smaller default or wait for a /models cache fill before showing
+        // accurate usage bars.
+        assert_eq!(
+            context_limit_for_model_with_provider("deepseek-v4", None),
+            Some(1_000_000)
+        );
+        assert_eq!(
+            context_limit_for_model_with_provider("deepseek-v4-flash", None),
+            Some(1_000_000)
+        );
+        assert_eq!(
+            context_limit_for_model_with_provider("deepseek-chat", None),
+            Some(1_000_000)
+        );
+        // Cached values must still take precedence so OAuth/online catalog
+        // hits can override the static fallback.
+        assert_eq!(
+            context_limit_for_model_with_provider_and_cache("deepseek-v4", None, |m| (m
+                == "deepseek-v4")
+                .then_some(64_000)),
+            Some(64_000)
+        );
+    }
+
     #[test]
     fn context_limit_uses_cache_for_unknown_models() {
         assert_eq!(