Add Inception Labs (Mercury) provider

Register Inception Labs' Mercury diffusion LLM as a new provider using
the OpenAI-compatible adapter at api.inceptionlabs.ai. Adds mercury and
mercury-coder to the model catalog and wires up all exhaustive match
arms across arc-llm, arc-agent, and arc-attractor.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.env.example

@@ -2,6 +2,7 @@ export ANTHROPIC_API_KEY=
 export BRAVE_SEARCH_API_KEY=
 export DAYTONA_API_KEY=
 export GEMINI_API_KEY=
+export INCEPTION_API_KEY=
 export KIMI_API_KEY=
 export MINIMAX_API_KEY=
 export OPENAI_API_KEY=

crates/arc-agent/src/cli.rs

@@ -17,7 +17,7 @@ pub struct AgentArgs {
     /// Task prompt
     pub prompt: String,
 
-    /// LLM provider (anthropic, openai, gemini, kimi, zai, minimax)
+    /// LLM provider (anthropic, openai, gemini, kimi, zai, minimax, inception)
     #[arg(long, default_value = "anthropic")]
     pub provider: String,
 
@@ -78,6 +78,7 @@ fn default_model(provider: Provider) -> &'static str {
         Provider::Kimi => "kimi-k2.5",
         Provider::Zai => "glm-4.7",
         Provider::Minimax => "minimax-m2.5",
+        Provider::Inception => "mercury",
     }
 }
 
@@ -159,6 +160,7 @@ fn summarizer_model_id(provider: Provider) -> ModelId {
         Provider::Kimi => ModelId::new(Provider::Kimi, "kimi-k2.5"),
         Provider::Zai => ModelId::new(Provider::Zai, "glm-4.7"),
         Provider::Minimax => ModelId::new(Provider::Minimax, "minimax-m2.5"),
+        Provider::Inception => ModelId::new(Provider::Inception, "mercury"),
     }
 }
 
@@ -174,7 +176,7 @@ fn build_profile(provider: Provider, model: &str, llm_client: Option<Client>) ->
     let summarizer = build_summarizer(provider, llm_client);
     match provider {
         Provider::OpenAi => Box::new(OpenAiProfile::with_summarizer(model, summarizer)),
-        Provider::Kimi | Provider::Zai | Provider::Minimax => Box::new(
+        Provider::Kimi | Provider::Zai | Provider::Minimax | Provider::Inception => Box::new(
             OpenAiProfile::with_summarizer(model, summarizer).with_provider(provider),
         ),
         Provider::Gemini => Box::new(GeminiProfile::with_summarizer(model, summarizer)),
@@ -192,6 +194,7 @@ fn validate_api_key(provider: Provider) -> bool {
         Provider::Kimi => std::env::var("KIMI_API_KEY").is_ok(),
         Provider::Zai => std::env::var("ZAI_API_KEY").is_ok(),
         Provider::Minimax => std::env::var("MINIMAX_API_KEY").is_ok(),
+        Provider::Inception => std::env::var("INCEPTION_API_KEY").is_ok(),
     }
 }
 
@@ -400,7 +403,7 @@ pub async fn run_with_args(args: AgentArgs) -> anyhow::Result<()> {
             Provider::OpenAi => {
                 Arc::new(OpenAiProfile::with_summarizer(&factory_model, child_summarizer))
             }
-            Provider::Kimi | Provider::Zai | Provider::Minimax => Arc::new(
+            Provider::Kimi | Provider::Zai | Provider::Minimax | Provider::Inception => Arc::new(
                 OpenAiProfile::with_summarizer(&factory_model, child_summarizer)
                     .with_provider(provider),
             ),
@@ -650,6 +653,11 @@ mod tests {
         assert_eq!(default_model(Provider::Minimax), "minimax-m2.5");
     }
 
+    #[test]
+    fn default_model_inception() {
+        assert_eq!(default_model(Provider::Inception), "mercury");
+    }
+
     // build_tool_approval non-interactive tests
 
     #[test]

crates/arc-agent/src/project_docs.rs

@@ -13,7 +13,7 @@ pub async fn discover_project_docs(
 
     let candidate_filenames: Vec<&str> = match provider {
         Provider::Anthropic => vec!["AGENTS.md", "CLAUDE.md"],
-        Provider::OpenAi | Provider::Kimi | Provider::Zai | Provider::Minimax => {
+        Provider::OpenAi | Provider::Kimi | Provider::Zai | Provider::Minimax | Provider::Inception => {
             vec!["AGENTS.md", ".codex/instructions.md"]
         }
         Provider::Gemini => vec!["AGENTS.md", "GEMINI.md"],

crates/arc-agent/tests/parity_matrix.rs

@@ -10,7 +10,7 @@ use arc_llm::provider::{ModelId, Provider};
 
 fn summarizer_model_id(provider: Provider) -> ModelId {
     match provider {
-        Provider::OpenAi | Provider::Kimi | Provider::Zai | Provider::Minimax => {
+        Provider::OpenAi | Provider::Kimi | Provider::Zai | Provider::Minimax | Provider::Inception => {
             ModelId::new(Provider::OpenAi, "gpt-4o-mini")
         }
         Provider::Gemini => ModelId::new(Provider::Gemini, "gemini-2.0-flash"),
@@ -32,7 +32,7 @@ fn build_profile(provider: Provider, model: &str, client: &Client) -> Box<dyn Pr
     match provider {
         Provider::Anthropic => Box::new(AnthropicProfile::with_summarizer(model, summarizer)),
         Provider::OpenAi => Box::new(OpenAiProfile::with_summarizer(model, summarizer)),
-        Provider::Kimi | Provider::Zai | Provider::Minimax => Box::new(
+        Provider::Kimi | Provider::Zai | Provider::Minimax | Provider::Inception => Box::new(
             OpenAiProfile::with_summarizer(model, summarizer).with_provider(provider),
         ),
         Provider::Gemini => Box::new(GeminiProfile::with_summarizer(model, summarizer)),
@@ -60,7 +60,7 @@ async fn make_session(provider: Provider, model: &str, cwd: &Path) -> Session {
                 Provider::OpenAi => {
                     Arc::new(OpenAiProfile::with_summarizer(&factory_model, summarizer))
                 }
-                Provider::Kimi | Provider::Zai | Provider::Minimax => Arc::new(
+                Provider::Kimi | Provider::Zai | Provider::Minimax | Provider::Inception => Arc::new(
                     OpenAiProfile::with_summarizer(&factory_model, summarizer)
                         .with_provider(provider),
                 ),

crates/arc-attractor/src/cli/backend.rs

@@ -76,7 +76,7 @@ impl AgentBackend {
         let factory: SessionFactory = Arc::new(move || {
             let child_profile: Arc<dyn ProviderProfile> = match factory_provider {
                 Provider::OpenAi => Arc::new(OpenAiProfile::new(&factory_model)),
-                Provider::Kimi | Provider::Zai | Provider::Minimax => Arc::new(
+                Provider::Kimi | Provider::Zai | Provider::Minimax | Provider::Inception => Arc::new(
                     OpenAiProfile::new(&factory_model).with_provider(factory_provider),
                 ),
                 Provider::Gemini => Arc::new(GeminiProfile::new(&factory_model)),
@@ -104,7 +104,7 @@ impl AgentBackend {
     fn build_profile(&self) -> Box<dyn ProviderProfile> {
         match self.provider {
             Provider::OpenAi => Box::new(OpenAiProfile::new(&self.model)),
-            Provider::Kimi | Provider::Zai | Provider::Minimax => {
+            Provider::Kimi | Provider::Zai | Provider::Minimax | Provider::Inception => {
                 Box::new(OpenAiProfile::new(&self.model).with_provider(self.provider))
             }
             Provider::Gemini => Box::new(GeminiProfile::new(&self.model)),

crates/arc-attractor/src/cli/cli_backend.rs

@@ -31,7 +31,7 @@ pub fn cli_command_for_provider(provider: Provider, model: &str, prompt_file: &s
         String::new()
     } else {
         match provider {
-            Provider::OpenAi | Provider::Gemini | Provider::Kimi | Provider::Zai | Provider::Minimax => {
+            Provider::OpenAi | Provider::Gemini | Provider::Kimi | Provider::Zai | Provider::Minimax | Provider::Inception => {
                 format!(" -m {model}")
             }
             Provider::Anthropic => format!(" --model {model}"),
@@ -39,7 +39,7 @@ pub fn cli_command_for_provider(provider: Provider, model: &str, prompt_file: &s
     };
     match provider {
         // --full-auto: sandboxed auto-execution, escalates on request
-        Provider::OpenAi | Provider::Kimi | Provider::Zai | Provider::Minimax => {
+        Provider::OpenAi | Provider::Kimi | Provider::Zai | Provider::Minimax | Provider::Inception => {
             format!("codex exec --json --full-auto{model_flag} < {prompt_file}")
         }
         // --yolo: auto-approve all tool calls
@@ -176,7 +176,7 @@ fn parse_gemini_json(output: &str) -> Option<CliResponse> {
 /// Parse CLI output, choosing the right parser based on provider.
 pub fn parse_cli_response(provider: Provider, output: &str) -> Option<CliResponse> {
     match provider {
-        Provider::OpenAi | Provider::Kimi | Provider::Zai | Provider::Minimax => {
+        Provider::OpenAi | Provider::Kimi | Provider::Zai | Provider::Minimax | Provider::Inception => {
             parse_codex_ndjson(output)
         }
         Provider::Gemini => parse_gemini_json(output),

crates/arc-llm/src/catalog.json

@@ -154,5 +154,31 @@
     "input_cost_per_million": null,
     "output_cost_per_million": null,
     "aliases": ["minimax"]
+  },
+  {
+    "id": "mercury",
+    "provider": "inception",
+    "display_name": "Mercury",
+    "context_window": 32768,
+    "max_output": null,
+    "supports_tools": true,
+    "supports_vision": false,
+    "supports_reasoning": false,
+    "input_cost_per_million": null,
+    "output_cost_per_million": null,
+    "aliases": []
+  },
+  {
+    "id": "mercury-coder",
+    "provider": "inception",
+    "display_name": "Mercury Coder",
+    "context_window": 32768,
+    "max_output": null,
+    "supports_tools": true,
+    "supports_vision": false,
+    "supports_reasoning": false,
+    "input_cost_per_million": null,
+    "output_cost_per_million": null,
+    "aliases": []
   }
 ]

crates/arc-llm/src/catalog.rs

@@ -62,7 +62,7 @@ mod tests {
     #[test]
     fn list_models_all() {
         let models = list_models(None);
-        assert_eq!(models.len(), 12);
+        assert_eq!(models.len(), 14);
     }
 
     #[test]
@@ -106,6 +106,22 @@ mod tests {
         assert_eq!(m.provider, "minimax");
     }
 
+    #[test]
+    fn mercury_in_catalog() {
+        let m = get_model_info("mercury").unwrap();
+        assert_eq!(m.provider, "inception");
+        assert_eq!(m.context_window, 32768);
+        assert!(m.supports_tools);
+        assert!(!m.supports_vision);
+        assert!(!m.supports_reasoning);
+    }
+
+    #[test]
+    fn mercury_coder_in_catalog() {
+        let m = get_model_info("mercury-coder").unwrap();
+        assert_eq!(m.provider, "inception");
+    }
+
     #[test]
     fn model_info_costs() {
         let claude = get_model_info("claude-opus-4-6").unwrap();

crates/arc-llm/src/client.rs

@@ -93,6 +93,12 @@ impl Client {
                     .with_name("minimax");
             client.register_provider(Arc::new(adapter)).await?;
         }
+        if let Ok(key) = std::env::var("INCEPTION_API_KEY") {
+            let adapter =
+                providers::OpenAiCompatibleAdapter::new(key, "https://api.inceptionlabs.ai/v1")
+                    .with_name("inception");
+            client.register_provider(Arc::new(adapter)).await?;
+        }
 
         Ok(client)
     }

crates/arc-llm/src/provider.rs

@@ -20,6 +20,7 @@ pub enum Provider {
     Kimi,
     Zai,
     Minimax,
+    Inception,
 }
 
 impl Provider {
@@ -34,6 +35,7 @@ impl Provider {
             Self::Kimi => "kimi",
             Self::Zai => "zai",
             Self::Minimax => "minimax",
+            Self::Inception => "inception",
         }
     }
 }
@@ -55,6 +57,7 @@ impl FromStr for Provider {
             "kimi" => Ok(Self::Kimi),
             "zai" => Ok(Self::Zai),
             "minimax" => Ok(Self::Minimax),
+            "inception" | "inception_labs" => Ok(Self::Inception),
             other => Err(format!("unknown provider: {other}")),
         }
     }
@@ -182,4 +185,15 @@ mod tests {
     fn minimax_as_str() {
         assert_eq!(Provider::Minimax.as_str(), "minimax");
     }
+
+    #[test]
+    fn parse_inception() {
+        assert_eq!("inception".parse::<Provider>().unwrap(), Provider::Inception);
+        assert_eq!("inception_labs".parse::<Provider>().unwrap(), Provider::Inception);
+    }
+
+    #[test]
+    fn inception_as_str() {
+        assert_eq!(Provider::Inception.as_str(), "inception");
+    }
 }