fix(ai): harden MiniMax reasoning and tool replay

crates/dbx-core/src/agent_loop.rs

@@ -1020,6 +1020,12 @@ fn context_window_for_model(model: &str) -> u32 {
     if m.contains("gpt-4.1") {
         return 1_000_000;
     }
+    if m.contains("minimax-m3") {
+        return 1_000_000;
+    }
+    if m.contains("minimax-m2") {
+        return 204_800;
+    }
     if m.contains("claude") || m.contains("o1") || m.starts_with("o3") || m.starts_with("o4") {
         200_000
     } else if m.contains("gpt-4") {
@@ -1031,6 +1037,10 @@ fn context_window_for_model(model: &str) -> u32 {
     }
 }
 
+fn effective_context_window(config: &AiConfig) -> u32 {
+    config.context_window.unwrap_or_else(|| context_window_for_model(&config.model))
+}
+
 fn prompt_budget(window: u32, max_tokens: Option<u32>) -> u32 {
     let output_reserve = max_tokens.unwrap_or(4096).min(window / 2);
     let safety_reserve = (window / 10).clamp(2048, 16_384).min(window / 2);
@@ -1061,7 +1071,7 @@ async fn maybe_compact(
     cancelled: &Notify,
     force: bool,
 ) -> CompactResult {
-    let window = config.context_window.unwrap_or_else(|| context_window_for_model(&config.model));
+    let window = effective_context_window(config);
     let budget = prompt_budget(window, max_tokens);
     let estimated_before = estimate_current_prompt_tokens(system_prompt, tools, messages);
 
@@ -1353,6 +1363,27 @@ mod tests {
         assert_eq!(clamp_max_agent_turns(u32::MAX), MAX_MAX_AGENT_TURNS);
     }
 
+    #[test]
+    fn minimax_context_windows_follow_official_model_families() {
+        assert_eq!(context_window_for_model("MiniMax-M3"), 1_000_000);
+        assert_eq!(context_window_for_model("vendor/MiniMax-M3.1"), 1_000_000);
+        assert_eq!(context_window_for_model("MiniMax-M2.7"), 204_800);
+        assert_eq!(context_window_for_model("MiniMax-M2.5-highspeed"), 204_800);
+        assert_eq!(context_window_for_model("MiniMax-future"), 128_000);
+    }
+
+    #[test]
+    fn explicit_context_window_overrides_minimax_family_default() {
+        let config: AiConfig = serde_json::from_value(serde_json::json!({
+            "provider": "minimax",
+            "model": "MiniMax-M3",
+            "contextWindow": 65_536
+        }))
+        .unwrap();
+
+        assert_eq!(effective_context_window(&config), 65_536);
+    }
+
     #[test]
     fn identifies_explicit_tool_rejection_errors() {
         for error in [