diff --git a/src/api/code_runner/languages.rs b/src/api/code_runner/languages.rs
new file mode 100644
index 0000000..4c80d1c
--- /dev/null
+++ b/src/api/code_runner/languages.rs
@@ -0,0 +1,181 @@
+//! 语言注册表与围栏代码块 info string 解析。
+//!
+//! 支持的语言通过 [`LANGUAGES`] 注册（镜像名、运行命令、默认资源限制、是否允许网络）。
+//! [`parse_fence_info`] 解析 markdown 围栏代码块的信息串，识别 `runnable` 标记与
+//! 可选的 JSON 资源覆盖（如 `python runnable {"timeout_secs":10}`）。
+//!
+//! 实际可用语言还受 `RUNNER_CONFIG.languages`（环境变量 `CODE_RUNNER_LANGUAGES`）双重约束：
+//! 既要在注册表中存在，也要在运维白名单中启用，才视为支持（[`is_supported_lang`]）。
+
+use std::collections::HashMap;
+use std::sync::LazyLock;
+
+use crate::infra::runner_config::{ResourceLimits, RUNNER_CONFIG};
+
+/// 单个语言的运行定义。
+pub struct LanguageDef {
+    pub name: String,
+    /// 容器镜像（task 12 的 docker build 产出，如 `yggdrasil-runner-python:latest`）。
+    pub image: String,
+    /// 容器内执行命令（源码会注入到 `/code/main.{ext}`）。
+    pub run_cmd: String,
+    pub extension: String,
+    pub default_limits: ResourceLimits,
+    /// 该语言本身是否允许网络（与全局/请求级 allow_network 取与）。
+    pub allow_network: bool,
+}
+
+/// 内置语言注册表。新增语言时在此 `insert`，并在 `.env.example` / `CODE_RUNNER_LANGUAGES`
+/// 中默认启用。
+pub static LANGUAGES: LazyLock<HashMap<String, LanguageDef>> = LazyLock::new(|| {
+    let mut m = HashMap::new();
+
+    m.insert(
+        "python".to_string(),
+        LanguageDef {
+            name: "python".to_string(),
+            image: "yggdrasil-runner-python:latest".to_string(),
+            run_cmd: "python /code/main.py".to_string(),
+            extension: "py".to_string(),
+            default_limits: ResourceLimits {
+                cpu_cores: 1.0,
+                memory_mb: 256,
+                timeout_secs: 5,
+                output_bytes: 1_048_576,
+                allow_network: false,
+            },
+            allow_network: false,
+        },
+    );
+
+    m.insert(
+        "node".to_string(),
+        LanguageDef {
+            name: "node".to_string(),
+            image: "yggdrasil-runner-node:latest".to_string(),
+            run_cmd: "node /code/main.js".to_string(),
+            extension: "js".to_string(),
+            default_limits: ResourceLimits {
+                cpu_cores: 1.0,
+                memory_mb: 256,
+                timeout_secs: 5,
+                output_bytes: 1_048_576,
+                allow_network: false,
+            },
+            allow_network: false,
+        },
+    );
+
+    m
+});
+
+/// 同时存在于注册表与运维白名单 (`RUNNER_CONFIG.languages`) 才视为支持。
+pub fn is_supported_lang(lang: &str) -> bool {
+    let clean = lang.trim().to_lowercase();
+    RUNNER_CONFIG.languages.iter().any(|l| l == &clean) && LANGUAGES.contains_key(&clean)
+}
+
+/// 解析围栏代码块的 info string。
+///
+/// 格式：`<lang> [runnable|run] [ {<ResourceLimits JSON>} ]`
+///
+/// 返回 `(lang, runnable, overrides)`。未知 token 静默忽略；JSON 解析失败时 overrides 为 None。
+pub fn parse_fence_info(info: &str) -> (String, bool, Option<ResourceLimits>) {
+    let tokens: Vec<&str> = info.split_whitespace().collect();
+    if tokens.is_empty() {
+        return ("".to_string(), false, None);
+    }
+    let lang = tokens[0].trim().to_lowercase();
+    let mut runnable = false;
+    let mut overrides = None;
+
+    if tokens.len() > 1 {
+        for &tok in &tokens[1..] {
+            if tok == "runnable" || tok == "run" {
+                runnable = true;
+            } else if tok.starts_with('{') {
+                if let Ok(limits) = serde_json::from_str::<ResourceLimits>(tok) {
+                    overrides = Some(limits);
+                }
+            }
+        }
+    }
+
+    (lang, runnable, overrides)
+}
+
+#[cfg(all(test, feature = "server"))]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parse_fence_info_runnable_marker() {
+        let (lang, runnable, overrides) = parse_fence_info("python runnable");
+        assert_eq!(lang, "python");
+        assert!(runnable);
+        assert!(overrides.is_none());
+    }
+
+    #[test]
+    fn parse_fence_info_run_alias() {
+        let (lang, runnable, _) = parse_fence_info("node run");
+        assert_eq!(lang, "node");
+        assert!(runnable);
+    }
+
+    #[test]
+    fn parse_fence_info_with_overrides() {
+        let (lang, runnable, overrides) =
+            parse_fence_info(r#"node runnable {"timeout_secs":10,"memory_mb":512,"allow_network":true,"cpu_cores":1.0,"output_bytes":1024}"#);
+        assert_eq!(lang, "node");
+        assert!(runnable);
+        let limits = overrides.unwrap();
+        assert_eq!(limits.timeout_secs, 10);
+        assert_eq!(limits.memory_mb, 512);
+        assert!(limits.allow_network);
+    }
+
+    #[test]
+    fn parse_fence_info_not_runnable() {
+        let (lang, runnable, _) = parse_fence_info("rust");
+        assert_eq!(lang, "rust");
+        assert!(!runnable);
+    }
+
+    #[test]
+    fn parse_fence_info_empty() {
+        let (lang, runnable, overrides) = parse_fence_info("");
+        assert_eq!(lang, "");
+        assert!(!runnable);
+        assert!(overrides.is_none());
+    }
+
+    #[test]
+    fn parse_fence_info_case_insensitive_lang() {
+        let (lang, _, _) = parse_fence_info("PYTHON runnable");
+        assert_eq!(lang, "python");
+    }
+
+    #[test]
+    fn parse_fence_info_malformed_json_yields_none() {
+        let (lang, runnable, overrides) = parse_fence_info(r#"python runnable {not valid json}"#);
+        assert_eq!(lang, "python");
+        assert!(runnable);
+        assert!(overrides.is_none(), "malformed JSON should yield None");
+    }
+
+    #[test]
+    fn is_supported_lang_default_whitelist() {
+        // 默认 CODE_RUNNER_LANGUAGES=python,node
+        assert!(is_supported_lang("python"));
+        assert!(is_supported_lang("node"));
+        assert!(!is_supported_lang("rust"));
+        assert!(!is_supported_lang(""));
+    }
+
+    #[test]
+    fn is_supported_lang_case_and_whitespace_insensitive() {
+        assert!(is_supported_lang(" Python "));
+        assert!(is_supported_lang("NODE"));
+    }
+}
diff --git a/src/api/code_runner/mod.rs b/src/api/code_runner/mod.rs
index d26bde9..c597826 100644
--- a/src/api/code_runner/mod.rs
+++ b/src/api/code_runner/mod.rs
@@ -73,6 +73,7 @@ pub struct ExecTask {
 
 // 子模块在后续任务中实现：
 // #[cfg(feature = "server")] pub mod execute;
-// #[cfg(feature = "server")] pub mod languages;
+#[cfg(feature = "server")]
+pub mod languages;
 #[cfg(feature = "server")]
 pub mod progress;