safe_chains/targets/
claude.rs

1use std::path::{Path, PathBuf};
2
3use serde::Deserialize;
4use serde_json::{Map, Value, json};
5
6use super::{HookFormat, HookInput, HookResponse, InstallOutcome, ParseError, Target, allow_reason};
7use crate::verdict::Verdict;
8
9pub struct ClaudeTarget;
10
11impl Target for ClaudeTarget {
12    fn name(&self) -> &'static str {
13        "claude"
14    }
15
16    fn display_name(&self) -> &'static str {
17        "Claude Code"
18    }
19
20    fn detect_paths(&self, home: &Path) -> Vec<PathBuf> {
21        vec![home.join(".claude")]
22    }
23
24    fn install(&self, home: &Path) -> Result<InstallOutcome, String> {
25        let dir = home.join(".claude");
26        if !dir.exists() {
27            return Ok(InstallOutcome::Skipped {
28                reason: format!(
29                    "~/.claude not found at {} (Claude Code not installed)",
30                    dir.display()
31                ),
32            });
33        }
34
35        let path = dir.join("settings.json");
36        let binary = "safe-chains";
37
38        if path.exists() {
39            let contents = std::fs::read_to_string(&path)
40                .map_err(|e| format!("Could not read {}: {e}", path.display()))?;
41            let mut settings: Value = serde_json::from_str(&contents)
42                .map_err(|e| format!("Could not parse {}: {e}", path.display()))?;
43
44            if has_safe_chains_hook(&settings) {
45                return Ok(InstallOutcome::AlreadyConfigured { path });
46            }
47
48            add_hook(&mut settings, binary);
49            let output = serde_json::to_string_pretty(&settings).expect("serializing valid JSON");
50            std::fs::write(&path, format!("{output}\n"))
51                .map_err(|e| format!("Could not write {}: {e}", path.display()))?;
52            Ok(InstallOutcome::Installed { path })
53        } else {
54            let mut settings = Value::Object(Map::new());
55            add_hook(&mut settings, binary);
56            let output = serde_json::to_string_pretty(&settings).expect("serializing valid JSON");
57            std::fs::write(&path, format!("{output}\n"))
58                .map_err(|e| format!("Could not write {}: {e}", path.display()))?;
59            Ok(InstallOutcome::Installed { path })
60        }
61    }
62
63    fn hook_format(&self) -> Option<&dyn HookFormat> {
64        Some(&ClaudeHookFormat)
65    }
66}
67
68struct ClaudeHookFormat;
69
70#[derive(Deserialize)]
71struct ToolInput {
72    command: String,
73}
74
75#[derive(Deserialize)]
76struct ClaudeHookEnvelope {
77    tool_input: ToolInput,
78    #[serde(default)]
79    cwd: Option<String>,
80}
81
82impl HookFormat for ClaudeHookFormat {
83    fn parse_input(&self, stdin: &str) -> Result<HookInput, ParseError> {
84        let envelope: ClaudeHookEnvelope = serde_json::from_str(stdin).map_err(|e| ParseError {
85            message: e.to_string(),
86        })?;
87        Ok(HookInput {
88            command: envelope.tool_input.command,
89            cwd: envelope.cwd,
90        })
91    }
92
93    fn render_response(&self, verdict: Verdict) -> HookResponse {
94        if verdict.is_allowed() {
95            let reason = allow_reason(verdict);
96            let body = json!({
97                "hookSpecificOutput": {
98                    "hookEventName": "PreToolUse",
99                    "permissionDecision": "allow",
100                    "permissionDecisionReason": reason,
101                }
102            });
103            HookResponse {
104                stdout: serde_json::to_string(&body).unwrap_or_default(),
105                exit_code: 0,
106            }
107        } else {
108            HookResponse {
109                stdout: String::new(),
110                exit_code: 0,
111            }
112        }
113    }
114}
115
116fn hook_entry(binary: &str) -> Value {
117    json!({
118        "matcher": "Bash",
119        "hooks": [{
120            "type": "command",
121            "command": binary,
122        }]
123    })
124}
125
126fn has_safe_chains_hook(settings: &Value) -> bool {
127    settings
128        .get("hooks")
129        .and_then(|h| h.get("PreToolUse"))
130        .and_then(|arr| arr.as_array())
131        .is_some_and(|entries| {
132            entries.iter().any(|entry| {
133                entry
134                    .get("hooks")
135                    .and_then(|h| h.as_array())
136                    .is_some_and(|hooks| {
137                        hooks.iter().any(|hook| {
138                            hook.get("command")
139                                .and_then(|c| c.as_str())
140                                .is_some_and(|cmd| cmd.contains("safe-chains"))
141                        })
142                    })
143            })
144        })
145}
146
147fn add_hook(settings: &mut Value, binary: &str) {
148    if !settings.is_object() {
149        *settings = json!({});
150    }
151    let Some(obj) = settings.as_object_mut() else {
152        unreachable!("settings was just set to an object");
153    };
154    let hooks = obj
155        .entry("hooks")
156        .or_insert_with(|| json!({}))
157        .as_object_mut()
158        .expect("hooks key was created above as an object");
159    let pre_tool_use = hooks
160        .entry("PreToolUse")
161        .or_insert_with(|| json!([]))
162        .as_array_mut()
163        .expect("PreToolUse key was created above as an array");
164    pre_tool_use.push(hook_entry(binary));
165}
166
167#[cfg(test)]
168mod tests {
169    use super::*;
170    use crate::verdict::SafetyLevel;
171
172    fn target() -> ClaudeTarget {
173        ClaudeTarget
174    }
175
176    #[test]
177    fn install_no_claude_dir_skips() {
178        let dir = tempfile::tempdir().unwrap();
179        let outcome = target().install(dir.path()).unwrap();
180        assert!(matches!(outcome, InstallOutcome::Skipped { .. }));
181    }
182
183    #[test]
184    fn install_creates_settings_file() {
185        let dir = tempfile::tempdir().unwrap();
186        std::fs::create_dir(dir.path().join(".claude")).unwrap();
187        let outcome = target().install(dir.path()).unwrap();
188        assert!(matches!(outcome, InstallOutcome::Installed { .. }));
189        let contents =
190            std::fs::read_to_string(dir.path().join(".claude/settings.json")).unwrap();
191        let settings: Value = serde_json::from_str(&contents).unwrap();
192        assert!(has_safe_chains_hook(&settings));
193    }
194
195    #[test]
196    fn install_preserves_existing_settings() {
197        let dir = tempfile::tempdir().unwrap();
198        let claude_dir = dir.path().join(".claude");
199        std::fs::create_dir(&claude_dir).unwrap();
200        std::fs::write(
201            claude_dir.join("settings.json"),
202            r#"{"permissions": {"allow": ["Bash(cargo test *)"]}}"#,
203        )
204        .unwrap();
205        target().install(dir.path()).unwrap();
206        let contents = std::fs::read_to_string(claude_dir.join("settings.json")).unwrap();
207        let settings: Value = serde_json::from_str(&contents).unwrap();
208        assert!(has_safe_chains_hook(&settings));
209        assert!(
210            settings
211                .get("permissions")
212                .and_then(|p| p.get("allow"))
213                .is_some(),
214            "existing permissions must be preserved"
215        );
216    }
217
218    #[test]
219    fn install_idempotent() {
220        let dir = tempfile::tempdir().unwrap();
221        std::fs::create_dir(dir.path().join(".claude")).unwrap();
222        target().install(dir.path()).unwrap();
223        let outcome = target().install(dir.path()).unwrap();
224        assert!(matches!(outcome, InstallOutcome::AlreadyConfigured { .. }));
225    }
226
227    #[test]
228    fn detect_paths_returns_claude_dir() {
229        let dir = tempfile::tempdir().unwrap();
230        let paths = target().detect_paths(dir.path());
231        assert_eq!(paths, vec![dir.path().join(".claude")]);
232    }
233
234    #[test]
235    fn parse_input_extracts_command() {
236        let stdin = r#"{"tool_input": {"command": "ls -la"}, "cwd": "/tmp"}"#;
237        let parsed = ClaudeHookFormat.parse_input(stdin).unwrap();
238        assert_eq!(parsed.command, "ls -la");
239        assert_eq!(parsed.cwd.as_deref(), Some("/tmp"));
240    }
241
242    #[test]
243    fn parse_input_rejects_garbage() {
244        assert!(ClaudeHookFormat.parse_input("not json").is_err());
245        assert!(ClaudeHookFormat.parse_input("{}").is_err());
246    }
247
248    #[test]
249    fn render_response_allow_emits_allow_envelope() {
250        let r = ClaudeHookFormat.render_response(Verdict::Allowed(SafetyLevel::Inert));
251        assert_eq!(r.exit_code, 0);
252        let v: Value = serde_json::from_str(&r.stdout).unwrap();
253        assert_eq!(
254            v.pointer("/hookSpecificOutput/permissionDecision")
255                .and_then(|d| d.as_str()),
256            Some("allow"),
257        );
258    }
259
260    #[test]
261    fn render_response_deny_emits_empty_body() {
262        let r = ClaudeHookFormat.render_response(Verdict::Denied);
263        assert_eq!(r.exit_code, 0);
264        assert_eq!(r.stdout, "");
265    }
266
267    #[test]
268    fn render_response_safewrite_carries_appropriate_reason() {
269        let r = ClaudeHookFormat.render_response(Verdict::Allowed(SafetyLevel::SafeWrite));
270        let v: Value = serde_json::from_str(&r.stdout).unwrap();
271        assert_eq!(
272            v.pointer("/hookSpecificOutput/permissionDecisionReason")
273                .and_then(|s| s.as_str()),
274            Some(allow_reason(Verdict::Allowed(SafetyLevel::SafeWrite))),
275        );
276    }
277}
safe_chains/targets/claude.rs

safe_chains/targets/
claude.rs
