execpolicycheck command in codex cli (#7012)

adding execpolicycheck tool onto codex cli

this is useful for validating policies (can be multiple) against
commands.

it will also surface errors in policy syntax:
<img width="1150" height="281" alt="Screenshot 2025-11-19 at 12 46
21 PM"
src="https://github.com/user-attachments/assets/8f99b403-564c-4172-acc9-6574a8d13dc3"
/>

this PR also changes output format when there's no match in the CLI.
instead of returning the raw string `noMatch`, we return
`{"noMatch":{}}`

this PR is a rewrite of: https://github.com/openai/codex/pull/6932 (due
to the numerous merge conflicts present in the original PR)

---------

Co-authored-by: Michael Bolin <mbolin@openai.com>

codex-rs/execpolicy/README.md

@@ -20,18 +20,18 @@ prefix_rule(
 ```
 
 ## CLI
-- Provide one or more policy files (for example `src/default.codexpolicy`) to check a command:
+- From the Codex CLI, run `codex execpolicy check` subcommand with one or more policy files (for example `src/default.codexpolicy`) to check a command:
+```bash
+codex execpolicy check --policy path/to/policy.codexpolicy git status
+```
+- Pass multiple `--policy` flags to merge rules, evaluated in the order provided, and use `--pretty` for formatted JSON.
+- You can also run the standalone dev binary directly during development:
 ```bash
 cargo run -p codex-execpolicy -- check --policy path/to/policy.codexpolicy git status
 ```
-- Pass multiple `--policy` flags to merge rules, evaluated in the order provided:
-```bash
-cargo run -p codex-execpolicy -- check --policy base.codexpolicy --policy overrides.codexpolicy git status
-```
-- Output is JSON by default; pass `--pretty` for pretty-printed JSON
 - Example outcomes:
   - Match: `{"match": { ... "decision": "allow" ... }}`
-  - No match: `"noMatch"`
+  - No match: `{"noMatch": {}}`
 
 ## Response shapes
 - Match:
@@ -53,8 +53,10 @@ cargo run -p codex-execpolicy -- check --policy base.codexpolicy --policy overri
 
 - No match:
 ```json
-"noMatch"
+{"noMatch": {}}
 ```
 
 - `matchedRules` lists every rule whose prefix matched the command; `matchedPrefix` is the exact prefix that matched.
 - The effective `decision` is the strictest severity across all matches (`forbidden` > `prompt` > `allow`).
+
+Note: `execpolicy` commands are still in preview. The API may have breaking changes in the future.

codex-rs/execpolicy/src/execpolicycheck.rs

@@ -0,0 +1,67 @@
+use std::fs;
+use std::path::PathBuf;
+
+use anyhow::Context;
+use anyhow::Result;
+use clap::Parser;
+
+use crate::Evaluation;
+use crate::Policy;
+use crate::PolicyParser;
+
+/// Arguments for evaluating a command against one or more execpolicy files.
+#[derive(Debug, Parser, Clone)]
+pub struct ExecPolicyCheckCommand {
+    /// Paths to execpolicy files to evaluate (repeatable).
+    #[arg(short = 'p', long = "policy", value_name = "PATH", required = true)]
+    pub policies: Vec<PathBuf>,
+
+    /// Pretty-print the JSON output.
+    #[arg(long)]
+    pub pretty: bool,
+
+    /// Command tokens to check against the policy.
+    #[arg(
+        value_name = "COMMAND",
+        required = true,
+        trailing_var_arg = true,
+        allow_hyphen_values = true
+    )]
+    pub command: Vec<String>,
+}
+
+impl ExecPolicyCheckCommand {
+    /// Load the policies for this command, evaluate the command, and render JSON output.
+    pub fn run(&self) -> Result<()> {
+        let policy = load_policies(&self.policies)?;
+        let evaluation = policy.check(&self.command);
+
+        let json = format_evaluation_json(&evaluation, self.pretty)?;
+        println!("{json}");
+
+        Ok(())
+    }
+}
+
+pub fn format_evaluation_json(evaluation: &Evaluation, pretty: bool) -> Result<String> {
+    if pretty {
+        serde_json::to_string_pretty(evaluation).map_err(Into::into)
+    } else {
+        serde_json::to_string(evaluation).map_err(Into::into)
+    }
+}
+
+pub fn load_policies(policy_paths: &[PathBuf]) -> Result<Policy> {
+    let mut parser = PolicyParser::new();
+
+    for policy_path in policy_paths {
+        let policy_file_contents = fs::read_to_string(policy_path)
+            .with_context(|| format!("failed to read policy at {}", policy_path.display()))?;
+        let policy_identifier = policy_path.to_string_lossy().to_string();
+        parser
+            .parse(&policy_identifier, &policy_file_contents)
+            .with_context(|| format!("failed to parse policy at {}", policy_path.display()))?;
+    }
+
+    Ok(parser.build())
+}

codex-rs/execpolicy/src/lib.rs

@@ -1,5 +1,6 @@
 pub mod decision;
 pub mod error;
+pub mod execpolicycheck;
 pub mod parser;
 pub mod policy;
 pub mod rule;
@@ -7,6 +8,7 @@ pub mod rule;
 pub use decision::Decision;
 pub use error::Error;
 pub use error::Result;
+pub use execpolicycheck::ExecPolicyCheckCommand;
 pub use parser::PolicyParser;
 pub use policy::Evaluation;
 pub use policy::Policy;

codex-rs/execpolicy/src/main.rs

@@ -1,66 +1,22 @@
-use std::fs;
-use std::path::PathBuf;
-
-use anyhow::Context;
 use anyhow::Result;
 use clap::Parser;
-use codex_execpolicy::PolicyParser;
+use codex_execpolicy::ExecPolicyCheckCommand;
 
 /// CLI for evaluating exec policies
 #[derive(Parser)]
 #[command(name = "codex-execpolicy")]
 enum Cli {
     /// Evaluate a command against a policy.
-    Check {
-        #[arg(short, long = "policy", value_name = "PATH", required = true)]
-        policies: Vec<PathBuf>,
-
-        /// Pretty-print the JSON output.
-        #[arg(long)]
-        pretty: bool,
-
-        /// Command tokens to check.
-        #[arg(
-            value_name = "COMMAND",
-            required = true,
-            trailing_var_arg = true,
-            allow_hyphen_values = true
-        )]
-        command: Vec<String>,
-    },
+    Check(ExecPolicyCheckCommand),
 }
 
 fn main() -> Result<()> {
     let cli = Cli::parse();
     match cli {
-        Cli::Check {
-            policies,
-            command,
-            pretty,
-        } => cmd_check(policies, command, pretty),
+        Cli::Check(cmd) => cmd_check(cmd),
     }
 }
 
-fn cmd_check(policy_paths: Vec<PathBuf>, args: Vec<String>, pretty: bool) -> Result<()> {
-    let policy = load_policies(&policy_paths)?;
-
-    let eval = policy.check(&args);
-    let json = if pretty {
-        serde_json::to_string_pretty(&eval)?
-    } else {
-        serde_json::to_string(&eval)?
-    };
-    println!("{json}");
-    Ok(())
-}
-
-fn load_policies(policy_paths: &[PathBuf]) -> Result<codex_execpolicy::Policy> {
-    let mut parser = PolicyParser::new();
-    for policy_path in policy_paths {
-        let policy_file_contents = fs::read_to_string(policy_path)
-            .with_context(|| format!("failed to read policy at {}", policy_path.display()))?;
-        let policy_identifier = policy_path.to_string_lossy().to_string();
-        parser.parse(&policy_identifier, &policy_file_contents)?;
-    }
-    Ok(parser.build())
+fn cmd_check(cmd: ExecPolicyCheckCommand) -> Result<()> {
+    cmd.run()
 }

codex-rs/execpolicy/src/policy.rs

@@ -27,9 +27,9 @@ impl Policy {
         let rules = match cmd.first() {
             Some(first) => match self.rules_by_program.get_vec(first) {
                 Some(rules) => rules,
-                None => return Evaluation::NoMatch,
+                None => return Evaluation::NoMatch {},
             },
-            None => return Evaluation::NoMatch,
+            None => return Evaluation::NoMatch {},
         };
 
         let matched_rules: Vec<RuleMatch> =
@@ -39,7 +39,7 @@ impl Policy {
                 decision,
                 matched_rules,
             },
-            None => Evaluation::NoMatch,
+            None => Evaluation::NoMatch {},
         }
     }
 
@@ -52,7 +52,7 @@ impl Policy {
             .into_iter()
             .flat_map(|command| match self.check(command.as_ref()) {
                 Evaluation::Match { matched_rules, .. } => matched_rules,
-                Evaluation::NoMatch => Vec::new(),
+                Evaluation::NoMatch { .. } => Vec::new(),
             })
             .collect();
 
@@ -61,7 +61,7 @@ impl Policy {
                 decision,
                 matched_rules,
             },
-            None => Evaluation::NoMatch,
+            None => Evaluation::NoMatch {},
         }
     }
 }
@@ -69,7 +69,7 @@ impl Policy {
 #[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub enum Evaluation {
-    NoMatch,
+    NoMatch {},
     Match {
         decision: Decision,
         #[serde(rename = "matchedRules")]

codex-rs/execpolicy/tests/basic.rs

@@ -288,7 +288,7 @@ prefix_rule(
         "color.status=always",
         "status",
     ]));
-    assert_eq!(Evaluation::NoMatch, no_match_eval);
+    assert_eq!(Evaluation::NoMatch {}, no_match_eval);
 }
 
 #[test]