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lean_ctx/hooks/agents/
codex.rs

1use super::super::{
2    ensure_codex_hooks_enabled as shared_ensure_codex_hooks_enabled, ensure_state_dir,
3    install_codex_instruction_docs, mcp_server_quiet_mode, resolve_hook_command_binary,
4    upsert_lean_ctx_codex_hook_entries, write_file,
5};
6
7pub fn install_codex_hook() {
8    let Some(codex_dir) = crate::core::home::resolve_codex_dir() else {
9        tracing::error!("Cannot resolve codex directory");
10        return;
11    };
12    if !ensure_state_dir(&codex_dir) {
13        return;
14    }
15
16    let hook_config_changed = install_codex_hook_config(&codex_dir);
17    let installed_docs = install_codex_instruction_docs(&codex_dir);
18
19    if !mcp_server_quiet_mode() {
20        if hook_config_changed {
21            eprintln!(
22                "Installed Codex-compatible SessionStart/PreToolUse hooks at {}",
23                codex_dir.display()
24            );
25        }
26        if installed_docs {
27            eprintln!("Installed Codex instructions at {}", codex_dir.display());
28        } else {
29            eprintln!("Codex AGENTS.md already configured.");
30        }
31    }
32}
33
34fn install_codex_hook_config(codex_dir: &std::path::Path) -> bool {
35    let binary = resolve_hook_command_binary();
36    let session_start_cmd = format!("{binary} hook codex-session-start");
37    let pre_tool_use_cmd = format!("{binary} hook codex-pretooluse");
38    let hooks_json_path = codex_dir.join("hooks.json");
39
40    let mut changed = false;
41    let mut root = if hooks_json_path.exists() {
42        if let Some(parsed) = std::fs::read_to_string(&hooks_json_path)
43            .ok()
44            .and_then(|content| crate::core::jsonc::parse_jsonc(&content).ok())
45        {
46            parsed
47        } else {
48            changed = true;
49            serde_json::json!({ "hooks": {} })
50        }
51    } else {
52        changed = true;
53        serde_json::json!({ "hooks": {} })
54    };
55
56    if upsert_lean_ctx_codex_hook_entries(&mut root, &session_start_cmd, &pre_tool_use_cmd) {
57        changed = true;
58    }
59
60    // Observe hooks for context awareness
61    let observe_cmd = format!("{binary} hook observe");
62    if ensure_codex_observe_hooks(&mut root, &observe_cmd) {
63        changed = true;
64    }
65
66    if changed {
67        write_file(
68            &hooks_json_path,
69            &serde_json::to_string_pretty(&root).unwrap_or_default(),
70        );
71    }
72
73    let rewrite_path = codex_dir.join("hooks").join("lean-ctx-rewrite-codex.sh");
74    if rewrite_path.exists() && std::fs::remove_file(&rewrite_path).is_ok() {
75        changed = true;
76    }
77
78    let config_toml_path = codex_dir.join("config.toml");
79    let config_content = std::fs::read_to_string(&config_toml_path).unwrap_or_default();
80
81    // Hybrid mode: ensure MCP server entry exists in config.toml so Codex
82    // Desktop/Cloud can reach lean-ctx even without CLI hooks.
83    let mcp_updated = ensure_codex_mcp_server(
84        &config_content,
85        &binary,
86        &super::super::mcp_server_env_pairs(),
87    );
88    let hooks_updated =
89        ensure_codex_hooks_enabled(mcp_updated.as_deref().unwrap_or(&config_content));
90
91    let final_content = hooks_updated
92        .or(mcp_updated)
93        .unwrap_or_else(|| config_content.clone());
94    if final_content != config_content {
95        write_file(&config_toml_path, &final_content);
96        changed = true;
97        if !mcp_server_quiet_mode() {
98            eprintln!(
99                "Updated Codex config (MCP server + hooks) in {}",
100                config_toml_path.display()
101            );
102        }
103    }
104
105    changed
106}
107
108fn ensure_codex_observe_hooks(root: &mut serde_json::Value, observe_cmd: &str) -> bool {
109    let original = root.clone();
110    let Some(hooks_obj) = root
111        .as_object_mut()
112        .and_then(|r| r.get_mut("hooks"))
113        .and_then(|h| h.as_object_mut())
114    else {
115        return false;
116    };
117
118    let observe_events = ["PostToolUse", "SessionStart", "SessionEnd"];
119    for event in observe_events {
120        let arr = hooks_obj
121            .entry(event.to_string())
122            .or_insert_with(|| serde_json::json!([]));
123        let Some(entries) = arr.as_array_mut() else {
124            continue;
125        };
126        let already = entries.iter().any(|e| {
127            e.get("hooks")
128                .and_then(|h| h.as_array())
129                .is_some_and(|hooks| {
130                    hooks.iter().any(|hook| {
131                        hook.get("command")
132                            .and_then(|c| c.as_str())
133                            .is_some_and(|c| c.contains("hook observe"))
134                    })
135                })
136        });
137        if !already {
138            entries.push(serde_json::json!({
139                "matcher": ".*",
140                "hooks": [{ "type": "command", "command": observe_cmd, "timeout": 5 }]
141            }));
142        }
143    }
144
145    *root != original
146}
147
148/// Idempotent upsert of the `[mcp_servers.lean-ctx]` entry in Codex `config.toml`.
149///
150/// Uses a format-preserving TOML editor so existing user content/comments and an
151/// orphaned `[mcp_servers.lean-ctx.env]` (issue #189) are normalized into a
152/// single valid section instead of producing a duplicate table header.
153///
154/// `env_pairs` is injected (not read from global state) so the pure
155/// config-rewriting logic is hermetically testable; the caller passes
156/// [`crate::hooks::mcp_server_env_pairs`]. Existing `command`/`args` are left
157/// untouched to respect user customization; env keys are upserted so a stale
158/// install gains `LEAN_CTX_PROJECT_ROOT`/`LEAN_CTX_EXTRA_ROOTS` (#403). Returns
159/// `None` when nothing changed, or when the file is not valid TOML (never
160/// clobbers an unparseable user config).
161fn ensure_codex_mcp_server(
162    config_content: &str,
163    binary: &str,
164    env_pairs: &[(String, String)],
165) -> Option<String> {
166    let mut doc = config_content.parse::<toml_edit::DocumentMut>().ok()?;
167    let original = doc.to_string();
168
169    // `[mcp_servers]` stays implicit so we never emit a bare parent header.
170    let servers = doc["mcp_servers"].or_insert(toml_edit::table());
171    if let Some(t) = servers.as_table_mut() {
172        t.set_implicit(true);
173    }
174
175    // `[mcp_servers.lean-ctx]` must be explicit so its header is rendered before
176    // the `.env` child table (fixes the orphaned-env ordering from #189).
177    let lean = servers["lean-ctx"].or_insert(toml_edit::table());
178    let lean_tbl = lean.as_table_mut()?;
179    lean_tbl.set_implicit(false);
180
181    // Respect user customization: only fill `command`/`args` when absent.
182    if !lean_tbl.contains_key("command") {
183        lean_tbl["command"] = toml_edit::value(binary);
184    }
185    if !lean_tbl.contains_key("args") {
186        lean_tbl["args"] = toml_edit::value(toml_edit::Array::new());
187    }
188
189    let env = lean_tbl["env"].or_insert(toml_edit::table());
190    if let Some(env_tbl) = env.as_table_mut() {
191        for (key, val) in env_pairs {
192            let key = key.as_str();
193            if env_tbl.get(key).and_then(toml_edit::Item::as_str) != Some(val.as_str()) {
194                env_tbl[key] = toml_edit::value(val.as_str());
195            }
196        }
197    }
198
199    let updated = doc.to_string();
200    (updated != original).then_some(updated)
201}
202
203fn ensure_codex_hooks_enabled(config_content: &str) -> Option<String> {
204    shared_ensure_codex_hooks_enabled(config_content)
205}
206
207// Codex deny is handled mode-aware by the codex-pretooluse handler at runtime:
208// non-rewritable Bash calls are denied in Replace mode, rewritten in Hybrid.
209// A separate deny hook is not needed (Codex PreToolUse only fires for Bash).
210
211#[cfg(test)]
212mod tests {
213    use super::{
214        ensure_codex_hooks_enabled, ensure_codex_mcp_server, upsert_lean_ctx_codex_hook_entries,
215    };
216    use serde_json::json;
217
218    /// Minimal env block (data dir only) for the config-rewrite tests that do
219    /// not exercise project-root/extra-roots propagation.
220    fn data_dir_pairs() -> Vec<(String, String)> {
221        vec![(
222            "LEAN_CTX_DATA_DIR".to_string(),
223            "/Users/user/.lean-ctx".to_string(),
224        )]
225    }
226
227    #[test]
228    fn upsert_replaces_legacy_codex_rewrite_but_keeps_custom_hooks() {
229        let mut input = json!({
230            "hooks": {
231                "PreToolUse": [
232                    {
233                        "matcher": "Bash",
234                        "hooks": [{
235                            "type": "command",
236                            "command": "/opt/homebrew/bin/lean-ctx hook rewrite",
237                            "timeout": 15
238                        }]
239                    },
240                    {
241                        "matcher": "Bash",
242                        "hooks": [{
243                            "type": "command",
244                            "command": "echo keep-me",
245                            "timeout": 5
246                        }]
247                    }
248                ],
249                "SessionStart": [
250                    {
251                        "matcher": "startup|resume|clear",
252                        "hooks": [{
253                            "type": "command",
254                            "command": "lean-ctx hook codex-session-start",
255                            "timeout": 15
256                        }]
257                    }
258                ],
259                "PostToolUse": [
260                    {
261                        "matcher": "Bash",
262                        "hooks": [{
263                            "type": "command",
264                            "command": "echo keep-post",
265                            "timeout": 5
266                        }]
267                    }
268                ]
269            }
270        });
271
272        let changed = upsert_lean_ctx_codex_hook_entries(
273            &mut input,
274            "lean-ctx hook codex-session-start",
275            "lean-ctx hook codex-pretooluse",
276        );
277        assert!(changed, "legacy hooks should be migrated");
278
279        let pre_tool_use = input["hooks"]["PreToolUse"]
280            .as_array()
281            .expect("PreToolUse array should remain");
282        assert_eq!(pre_tool_use.len(), 2, "custom hook should be preserved");
283        assert_eq!(
284            pre_tool_use[0]["hooks"][0]["command"].as_str(),
285            Some("echo keep-me")
286        );
287        assert_eq!(
288            pre_tool_use[1]["hooks"][0]["command"].as_str(),
289            Some("lean-ctx hook codex-pretooluse")
290        );
291        assert_eq!(
292            input["hooks"]["SessionStart"][0]["hooks"][0]["command"].as_str(),
293            Some("lean-ctx hook codex-session-start")
294        );
295        assert_eq!(
296            input["hooks"]["PostToolUse"][0]["hooks"][0]["command"].as_str(),
297            Some("echo keep-post")
298        );
299    }
300
301    #[test]
302    fn ignores_non_lean_ctx_codex_entries() {
303        let custom = json!({
304            "matcher": "Bash",
305            "hooks": [{
306                "type": "command",
307                "command": "echo keep-me",
308                "timeout": 5
309            }]
310        });
311        assert!(
312            !crate::hooks::support::is_lean_ctx_codex_managed_entry("PreToolUse", &custom),
313            "custom Codex hooks must be preserved"
314        );
315    }
316
317    #[test]
318    fn detects_managed_codex_session_start_entry() {
319        let managed = json!({
320            "matcher": "startup|resume|clear",
321            "hooks": [{
322                "type": "command",
323                "command": "/opt/homebrew/bin/lean-ctx hook codex-session-start",
324                "timeout": 15
325            }]
326        });
327        assert!(crate::hooks::support::is_lean_ctx_codex_managed_entry(
328            "SessionStart",
329            &managed
330        ));
331    }
332
333    #[test]
334    fn ensure_codex_hooks_enabled_updates_existing_features_flag() {
335        let input = "\
336[features]
337other = true
338codex_hooks = false
339
340[mcp_servers.other]
341command = \"other\"
342";
343
344        let output =
345            ensure_codex_hooks_enabled(input).expect("codex_hooks=false should be migrated");
346
347        assert!(output.contains("[features]\nother = true\nhooks = true\n"));
348        assert!(!output.contains("codex_hooks = false"));
349    }
350
351    #[test]
352    fn ensure_codex_hooks_enabled_moves_stray_assignment_into_features_section() {
353        let input = "\
354[features]
355other = true
356
357[mcp_servers.lean-ctx]
358command = \"lean-ctx\"
359codex_hooks = true
360";
361
362        let output = ensure_codex_hooks_enabled(input)
363            .expect("stray codex_hooks assignment should be normalized");
364
365        assert!(output.contains("[features]\nother = true\nhooks = true\n"));
366        assert_eq!(output.matches("hooks = true").count(), 1);
367        assert!(!output.contains("[mcp_servers.lean-ctx]\ncommand = \"lean-ctx\"\nhooks = true"));
368    }
369
370    #[test]
371    fn ensure_codex_hooks_enabled_adds_features_section_when_missing() {
372        let input = "\
373[mcp_servers.lean-ctx]
374command = \"lean-ctx\"
375";
376
377        let output =
378            ensure_codex_hooks_enabled(input).expect("missing features section should be added");
379
380        assert!(output.ends_with("\n[features]\nhooks = true\n"));
381    }
382
383    #[test]
384    fn codex_docs_steer_to_reliable_mcp_path_without_false_hook_claim() {
385        let tmp = std::env::temp_dir().join("lean-ctx-test-codex-desktop-note");
386        let _ = std::fs::remove_dir_all(&tmp);
387        std::fs::create_dir_all(&tmp).unwrap();
388
389        crate::hooks::support::install_codex_instruction_docs(&tmp);
390
391        let lean_ctx_md = std::fs::read_to_string(tmp.join("LEAN-CTX.md")).unwrap();
392        assert!(
393            lean_ctx_md.contains("ctx_shell") && lean_ctx_md.contains("ctx_read"),
394            "LEAN-CTX.md must steer the agent to the MCP tools"
395        );
396        // Regression guard for #350: never assert as fact that Desktop/Cloud hooks
397        // do not run — they can (gated by trust via /hooks, varies by version).
398        let normalized = lean_ctx_md.replace('\n', " ");
399        assert!(
400            !normalized.contains("hooks do not run")
401                && !normalized.contains("no automatic compression"),
402            "LEAN-CTX.md must not make the false blanket claim that Codex Desktop hooks never run (#350)"
403        );
404
405        let agents_md = std::fs::read_to_string(tmp.join("AGENTS.md")).unwrap();
406        assert!(
407            agents_md.contains("ctx_shell") && agents_md.contains("ctx_search"),
408            "AGENTS.md block must steer to the reliable MCP tools"
409        );
410        let agents_norm = agents_md.replace('\n', " ");
411        assert!(
412            !agents_norm.contains("hooks do not run"),
413            "AGENTS.md must not claim Codex hooks never run (#350)"
414        );
415
416        let _ = std::fs::remove_dir_all(&tmp);
417    }
418
419    #[test]
420    fn install_codex_docs_preserves_existing_user_instructions() {
421        let tmp = std::env::temp_dir().join("lean-ctx-test-codex-preserve");
422        let _ = std::fs::remove_dir_all(&tmp);
423        std::fs::create_dir_all(&tmp).unwrap();
424
425        let agents_md = tmp.join("AGENTS.md");
426        let user_content = "# My Custom Instructions\n\nDo not change my codebase style.\n\n## Rules\n- Always use tabs\n- No semicolons\n";
427        std::fs::write(&agents_md, user_content).unwrap();
428
429        crate::hooks::support::install_codex_instruction_docs(&tmp);
430
431        let result = std::fs::read_to_string(&agents_md).unwrap();
432        assert!(
433            result.contains("My Custom Instructions"),
434            "user content must be preserved"
435        );
436        assert!(
437            result.contains("Always use tabs"),
438            "user rules must be preserved"
439        );
440        assert!(
441            result.contains(crate::core::rules_canonical::AGENTS_BLOCK_START),
442            "lean-ctx block must be appended"
443        );
444        let expected_ref = tmp.join("LEAN-CTX.md").display().to_string();
445        assert!(
446            result.contains(&expected_ref),
447            "lean-ctx reference must use codex_dir path"
448        );
449
450        let _ = std::fs::remove_dir_all(&tmp);
451    }
452
453    #[test]
454    fn install_codex_docs_updates_only_marked_block() {
455        let tmp = std::env::temp_dir().join("lean-ctx-test-codex-marked");
456        let _ = std::fs::remove_dir_all(&tmp);
457        std::fs::create_dir_all(&tmp).unwrap();
458
459        let agents_md = tmp.join("AGENTS.md");
460        let content_with_block = format!(
461            "# My Instructions\n\nCustom rule here.\n\n{}\n## lean-ctx\n\n@OLD-LEAN-CTX.md\n{}\n\n## Other Section\nKeep this.\n",
462            crate::core::rules_canonical::AGENTS_BLOCK_START,
463            crate::core::rules_canonical::AGENTS_BLOCK_END,
464        );
465        std::fs::write(&agents_md, content_with_block).unwrap();
466
467        crate::hooks::support::install_codex_instruction_docs(&tmp);
468
469        let result = std::fs::read_to_string(&agents_md).unwrap();
470        assert!(
471            result.contains("Custom rule here."),
472            "user content before block preserved"
473        );
474        assert!(
475            result.contains("Other Section"),
476            "user content after block preserved"
477        );
478        let expected_ref = tmp.join("LEAN-CTX.md").display().to_string();
479        assert!(
480            result.contains(&expected_ref),
481            "block updated to current reference"
482        );
483        assert!(
484            !result.contains("OLD-LEAN-CTX"),
485            "old block content replaced"
486        );
487
488        let _ = std::fs::remove_dir_all(&tmp);
489    }
490
491    #[test]
492    fn ensure_mcp_server_adds_section_when_missing() {
493        let input = "[features]\ncodex_hooks = true\n";
494        let result = ensure_codex_mcp_server(input, "lean-ctx", &data_dir_pairs())
495            .expect("should add MCP section");
496        assert!(result.contains("[mcp_servers.lean-ctx]"));
497        assert!(result.contains("command = \"lean-ctx\""));
498        assert!(result.contains("args = []"));
499        assert!(result.contains("[features]\ncodex_hooks = true\n"));
500    }
501
502    #[test]
503    fn ensure_mcp_server_noop_when_already_complete() {
504        // Parent + args + an env block already carrying every desired key: the
505        // upsert must be a true no-op (no churn on every session start).
506        let input = "[mcp_servers.lean-ctx]\ncommand = \"lean-ctx\"\nargs = []\n\n\
507                     [mcp_servers.lean-ctx.env]\nLEAN_CTX_DATA_DIR = \"/Users/user/.lean-ctx\"\n";
508        assert!(
509            ensure_codex_mcp_server(input, "lean-ctx", &data_dir_pairs()).is_none(),
510            "should not modify config when MCP section already has all keys"
511        );
512    }
513
514    #[test]
515    fn ensure_mcp_server_preserves_existing_sections() {
516        let input = "[mcp_servers.other]\ncommand = \"other\"\n";
517        let result = ensure_codex_mcp_server(input, "/usr/bin/lean-ctx", &data_dir_pairs())
518            .expect("should add lean-ctx section");
519        assert!(result.contains("[mcp_servers.other]"));
520        assert!(result.contains("[mcp_servers.lean-ctx]"));
521        assert!(result.contains("command = \"/usr/bin/lean-ctx\""));
522    }
523
524    #[test]
525    fn ensure_mcp_server_inserts_before_orphaned_env_subtable() {
526        let input = "\
527[mcp_servers.lean-ctx.env]
528LEAN_CTX_DATA_DIR = \"/Users/user/.lean-ctx\"
529";
530        let result = ensure_codex_mcp_server(input, "/usr/local/bin/lean-ctx", &data_dir_pairs())
531            .expect("should insert parent section before orphaned env");
532        let parent_pos = result
533            .find("[mcp_servers.lean-ctx]")
534            .expect("parent section must exist");
535        let env_pos = result
536            .find("[mcp_servers.lean-ctx.env]")
537            .expect("env sub-table must be preserved");
538        assert!(
539            parent_pos < env_pos,
540            "parent section must come before env sub-table"
541        );
542        assert!(result.contains("command = \"/usr/local/bin/lean-ctx\""));
543        assert!(result.contains("LEAN_CTX_DATA_DIR"));
544        assert_eq!(
545            result.matches("[mcp_servers.lean-ctx.env]").count(),
546            1,
547            "must not duplicate the env table (would be invalid TOML)"
548        );
549    }
550
551    #[test]
552    fn ensure_mcp_server_handles_issue_189_scenario() {
553        let input = "\
554source = \"/Users/user/.cache/codex-runtimes/codex-primary-runtime/plugins/openai-primary-runtime\"
555source_type = \"local\"
556
557[mcp_servers.lean-ctx.env]
558LEAN_CTX_DATA_DIR = \"/Users/user/.lean-ctx\"
559";
560        let result = ensure_codex_mcp_server(input, "/usr/local/bin/lean-ctx", &data_dir_pairs())
561            .expect("should fix orphaned config from issue #189");
562        assert!(result.contains("[mcp_servers.lean-ctx]\n"));
563        assert!(result.contains("command = \"/usr/local/bin/lean-ctx\""));
564        assert!(result.contains("[mcp_servers.lean-ctx.env]"));
565        assert!(result.contains("LEAN_CTX_DATA_DIR"));
566
567        let parent_pos = result.find("[mcp_servers.lean-ctx]\n").unwrap();
568        let env_pos = result.find("[mcp_servers.lean-ctx.env]").unwrap();
569        assert!(parent_pos < env_pos);
570        assert_eq!(
571            result.matches("[mcp_servers.lean-ctx.env]").count(),
572            1,
573            "issue #189 fix must merge into one env table, not duplicate it"
574        );
575        // Original sibling content must survive the normalization.
576        assert!(result.contains("source_type = \"local\""));
577    }
578
579    #[test]
580    fn ensure_mcp_server_quotes_windows_backslash_paths() {
581        let input = "[features]\ncodex_hooks = true\n";
582        let win_path = r"C:\Users\Foo\AppData\Roaming\npm\lean-ctx.cmd";
583        let result = ensure_codex_mcp_server(input, win_path, &data_dir_pairs())
584            .expect("should add MCP section");
585        // Quote style is the TOML editor's concern; what matters is that the
586        // backslash path round-trips to exactly the same string and stays valid.
587        let doc = result
588            .parse::<toml_edit::DocumentMut>()
589            .expect("output must be valid TOML");
590        assert_eq!(
591            doc["mcp_servers"]["lean-ctx"]["command"].as_str(),
592            Some(win_path),
593            "Windows backslash path must round-trip exactly: {result}"
594        );
595    }
596
597    #[test]
598    fn ensure_mcp_server_does_not_match_similarly_named_section() {
599        let input = "\
600[mcp_servers.lean-ctx-other]
601command = \"other\"
602";
603        let result = ensure_codex_mcp_server(input, "lean-ctx", &data_dir_pairs())
604            .expect("should add lean-ctx section despite similarly-named section");
605        assert!(result.contains("[mcp_servers.lean-ctx]\n"));
606        assert!(result.contains("[mcp_servers.lean-ctx-other]"));
607    }
608
609    #[test]
610    fn ensure_mcp_server_writes_project_and_extra_roots() {
611        // #403: when init captured a project root + sibling worktrees, those
612        // must be propagated into the env block so the long-lived MCP server
613        // resolves explicit paths under every root.
614        let pairs = vec![
615            (
616                "LEAN_CTX_DATA_DIR".to_string(),
617                "/home/u/.lean-ctx".to_string(),
618            ),
619            (
620                "LEAN_CTX_PROJECT_ROOT".to_string(),
621                "/work/main".to_string(),
622            ),
623            (
624                "LEAN_CTX_EXTRA_ROOTS".to_string(),
625                "/work/wt-a:/work/wt-b".to_string(),
626            ),
627        ];
628        let result =
629            ensure_codex_mcp_server("", "lean-ctx", &pairs).expect("fresh config must be created");
630
631        let doc = result
632            .parse::<toml_edit::DocumentMut>()
633            .expect("output must be valid TOML");
634        let env = &doc["mcp_servers"]["lean-ctx"]["env"];
635        assert_eq!(env["LEAN_CTX_PROJECT_ROOT"].as_str(), Some("/work/main"));
636        assert_eq!(
637            env["LEAN_CTX_EXTRA_ROOTS"].as_str(),
638            Some("/work/wt-a:/work/wt-b")
639        );
640        assert_eq!(env["LEAN_CTX_DATA_DIR"].as_str(), Some("/home/u/.lean-ctx"));
641    }
642
643    #[test]
644    fn ensure_mcp_server_upserts_missing_keys_into_existing_env() {
645        // Pre-existing install (only DATA_DIR) must gain the new roots without
646        // duplicating the section, and the operation must be idempotent.
647        let input = "[mcp_servers.lean-ctx]\ncommand = \"lean-ctx\"\nargs = []\n\n\
648                     [mcp_servers.lean-ctx.env]\nLEAN_CTX_DATA_DIR = \"/home/u/.lean-ctx\"\n";
649        let pairs = vec![
650            (
651                "LEAN_CTX_DATA_DIR".to_string(),
652                "/home/u/.lean-ctx".to_string(),
653            ),
654            (
655                "LEAN_CTX_PROJECT_ROOT".to_string(),
656                "/work/main".to_string(),
657            ),
658        ];
659
660        let result = ensure_codex_mcp_server(input, "lean-ctx", &pairs)
661            .expect("should upsert the missing project root");
662        assert_eq!(
663            result.matches("[mcp_servers.lean-ctx]").count(),
664            1,
665            "must not duplicate the parent section"
666        );
667        let doc = result
668            .parse::<toml_edit::DocumentMut>()
669            .expect("output must be valid TOML");
670        assert_eq!(
671            doc["mcp_servers"]["lean-ctx"]["env"]["LEAN_CTX_PROJECT_ROOT"].as_str(),
672            Some("/work/main")
673        );
674
675        // Second pass over the upserted config is a no-op.
676        assert!(
677            ensure_codex_mcp_server(&result, "lean-ctx", &pairs).is_none(),
678            "upsert must be idempotent"
679        );
680    }
681}