[codex] Fix VS Code session previews (#3593)

* Fix Codex VS Code session previews

* fix(codex): use last IDE request heading for session previews

A markdown heading inside the active selection / open file could precede the real injected request, so matching the first "## My request for Codex:" heading picked selection content instead of the user prompt. Scan for the last matching heading (the IDE injects the real request as the final section) on both the Rust title path and the frontend TOC preview path.

Add regression tests for the selection-heading case, and pin the known best-effort limitation when the request body itself repeats the heading.

---------

Co-authored-by: Jason <farion1231@gmail.com>

src-tauri/src/session_manager/providers/codex.rs

@@ -15,6 +15,8 @@ use super::utils::{
 };
 
 const PROVIDER_ID: &str = "codex";
+const VSCODE_CONTEXT_PREFIX: &str = "# Context from my IDE setup:";
+const CODEX_REQUEST_MARKER: &str = "my request for codex";
 
 static UUID_RE: LazyLock<Regex> = LazyLock::new(|| {
     Regex::new(r"[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}")
@@ -186,12 +188,8 @@ fn parse_session(path: &Path) -> Option<SessionMeta> {
                     && payload.get("role").and_then(Value::as_str) == Some("user")
                 {
                     let text = payload.get("content").map(extract_text).unwrap_or_default();
-                    let trimmed = text.trim();
-                    if !trimmed.is_empty()
-                        && !trimmed.starts_with("# AGENTS.md")
-                        && !trimmed.starts_with("<environment_context>")
-                    {
-                        first_user_message = Some(trimmed.to_string());
+                    if let Some(title) = title_candidate_from_user_message(&text) {
+                        first_user_message = Some(title);
                     }
                 }
             }
@@ -266,6 +264,80 @@ fn is_subagent_source(source: Option<&Value>) -> bool {
         .unwrap_or(false)
 }
 
+fn title_candidate_from_user_message(text: &str) -> Option<String> {
+    let trimmed = text.trim();
+    if trimmed.is_empty()
+        || trimmed.starts_with("# AGENTS.md")
+        || trimmed.starts_with("<environment_context>")
+    {
+        return None;
+    }
+
+    if trimmed.starts_with(VSCODE_CONTEXT_PREFIX) {
+        return extract_codex_prompt_from_ide_context(trimmed);
+    }
+
+    Some(trimmed.to_string())
+}
+
+fn extract_codex_prompt_from_ide_context(text: &str) -> Option<String> {
+    let normalized = text.replace("\r\n", "\n");
+    let lines = normalized.lines().collect::<Vec<_>>();
+
+    // VS Code injects the real prompt as the LAST "## My request for Codex:"
+    // section, so keep the final matching heading. Earlier matches can be
+    // headings that live inside the active selection / open file content.
+    // Trade-off: if the request body itself repeats the heading, the title
+    // truncates to its trailing part (rare; covered by tests below).
+    let mut prompt: Option<String> = None;
+    for (index, line) in lines.iter().enumerate() {
+        let Some(inline_prompt) = codex_request_heading_payload(line) else {
+            continue;
+        };
+
+        if !inline_prompt.is_empty() {
+            prompt = Some(inline_prompt.to_string());
+            continue;
+        }
+
+        let following_prompt = lines[index + 1..].join("\n").trim().to_string();
+        prompt = (!following_prompt.is_empty()).then_some(following_prompt);
+    }
+
+    prompt
+}
+
+fn codex_request_heading_payload(line: &str) -> Option<&str> {
+    let trimmed = line.trim();
+    if !trimmed.starts_with('#') {
+        return None;
+    }
+
+    let heading = trimmed.trim_start_matches('#').trim_start();
+    let lowered = heading.to_ascii_lowercase();
+    if !lowered.starts_with(CODEX_REQUEST_MARKER) {
+        return None;
+    }
+
+    let suffix = heading[CODEX_REQUEST_MARKER.len()..].trim_start();
+    if suffix.is_empty() {
+        return Some("");
+    }
+
+    let Some(separator) = suffix.chars().next() else {
+        return Some("");
+    };
+    if !matches!(separator, ':' | '：' | '-' | '—') {
+        return None;
+    }
+
+    Some(
+        suffix
+            .trim_start_matches(|c: char| c.is_whitespace() || matches!(c, ':' | '：' | '-' | '—'))
+            .trim(),
+    )
+}
+
 fn infer_session_id_from_filename(path: &Path) -> Option<String> {
     let file_name = path.file_name()?.to_string_lossy();
     UUID_RE.find(&file_name).map(|mat| mat.as_str().to_string())
@@ -426,6 +498,114 @@ mod tests {
         assert_eq!(meta.title.as_deref(), Some("Fix the login bug"));
     }
 
+    #[test]
+    fn parse_session_extracts_vscode_ide_request_as_title() {
+        let temp = tempdir().expect("tempdir");
+        let path = temp.path().join("session.jsonl");
+        std::fs::write(
+            &path,
+            concat!(
+                "{\"timestamp\":\"2026-03-06T21:50:12Z\",\"type\":\"session_meta\",\"payload\":{\"id\":\"test-id\",\"cwd\":\"/tmp/project\"}}\n",
+                "{\"timestamp\":\"2026-03-06T21:50:13Z\",\"type\":\"response_item\",\"payload\":{\"type\":\"message\",\"role\":\"user\",\"content\":\"# Context from my IDE setup:\\n\\n## Active file: src/main.ts\\n\\n## My request for Codex:\\nFix the session title preview\"}}\n"
+            ),
+        )
+        .expect("write");
+
+        let meta = parse_session(&path).unwrap();
+        assert_eq!(meta.title.as_deref(), Some("Fix the session title preview"));
+    }
+
+    #[test]
+    fn parse_session_extracts_inline_vscode_ide_request_as_title() {
+        let temp = tempdir().expect("tempdir");
+        let path = temp.path().join("session.jsonl");
+        std::fs::write(
+            &path,
+            concat!(
+                "{\"timestamp\":\"2026-03-06T21:50:12Z\",\"type\":\"session_meta\",\"payload\":{\"id\":\"test-id\",\"cwd\":\"/tmp/project\"}}\n",
+                "{\"timestamp\":\"2026-03-06T21:50:13Z\",\"type\":\"response_item\",\"payload\":{\"type\":\"message\",\"role\":\"user\",\"content\":\"# Context from my IDE setup:\\n\\n## My request for Codex: Fix the TOC preview\"}}\n"
+            ),
+        )
+        .expect("write");
+
+        let meta = parse_session(&path).unwrap();
+        assert_eq!(meta.title.as_deref(), Some("Fix the TOC preview"));
+    }
+
+    #[test]
+    fn parse_session_ignores_marker_mentions_before_request_heading() {
+        let temp = tempdir().expect("tempdir");
+        let path = temp.path().join("session.jsonl");
+        std::fs::write(
+            &path,
+            concat!(
+                "{\"timestamp\":\"2026-03-06T21:50:12Z\",\"type\":\"session_meta\",\"payload\":{\"id\":\"test-id\",\"cwd\":\"/tmp/project\"}}\n",
+                "{\"timestamp\":\"2026-03-06T21:50:13Z\",\"type\":\"response_item\",\"payload\":{\"type\":\"message\",\"role\":\"user\",\"content\":\"# Context from my IDE setup:\\n\\n## Active selection:\\nMy request for Codex: not the prompt\\n\\n## My request for Codex:\\nUse the real request heading\"}}\n"
+            ),
+        )
+        .expect("write");
+
+        let meta = parse_session(&path).unwrap();
+        assert_eq!(meta.title.as_deref(), Some("Use the real request heading"));
+    }
+
+    #[test]
+    fn parse_session_uses_last_request_heading_when_selection_has_one() {
+        let temp = tempdir().expect("tempdir");
+        let path = temp.path().join("session.jsonl");
+        std::fs::write(
+            &path,
+            concat!(
+                "{\"timestamp\":\"2026-03-06T21:50:12Z\",\"type\":\"session_meta\",\"payload\":{\"id\":\"test-id\",\"cwd\":\"/tmp/project\"}}\n",
+                "{\"timestamp\":\"2026-03-06T21:50:13Z\",\"type\":\"response_item\",\"payload\":{\"type\":\"message\",\"role\":\"user\",\"content\":\"# Context from my IDE setup:\\n\\n## Active selection: docs/codex-format.md\\n## My request for Codex:\\nselected document content, not the real request\\n\\n## My request for Codex:\\nUse the last request heading\"}}\n"
+            ),
+        )
+        .expect("write");
+
+        let meta = parse_session(&path).unwrap();
+        assert_eq!(meta.title.as_deref(), Some("Use the last request heading"));
+    }
+
+    // Known limitation: the IDE marker is matched purely by text, so a
+    // "## My request for Codex:" line inside the real request body is treated as
+    // a new boundary and only the trailing part is kept. This pins the
+    // best-effort behavior; fully fixing it needs structured IDE section data
+    // that the Codex VS Code context does not provide.
+    #[test]
+    fn parse_session_keeps_trailing_part_when_request_body_repeats_heading() {
+        let temp = tempdir().expect("tempdir");
+        let path = temp.path().join("session.jsonl");
+        std::fs::write(
+            &path,
+            concat!(
+                "{\"timestamp\":\"2026-03-06T21:50:12Z\",\"type\":\"session_meta\",\"payload\":{\"id\":\"test-id\",\"cwd\":\"/tmp/project\"}}\n",
+                "{\"timestamp\":\"2026-03-06T21:50:13Z\",\"type\":\"response_item\",\"payload\":{\"type\":\"message\",\"role\":\"user\",\"content\":\"# Context from my IDE setup:\\n\\n## Active file: foo.ts\\n\\n## My request for Codex:\\nDocument the format, for example:\\n## My request for Codex:\\nand the rest follows.\"}}\n"
+            ),
+        )
+        .expect("write");
+
+        let meta = parse_session(&path).unwrap();
+        assert_eq!(meta.title.as_deref(), Some("and the rest follows."));
+    }
+
+    #[test]
+    fn parse_session_skips_vscode_ide_context_without_request() {
+        let temp = tempdir().expect("tempdir");
+        let path = temp.path().join("session.jsonl");
+        std::fs::write(
+            &path,
+            concat!(
+                "{\"timestamp\":\"2026-03-06T21:50:12Z\",\"type\":\"session_meta\",\"payload\":{\"id\":\"test-id\",\"cwd\":\"/tmp/project\"}}\n",
+                "{\"timestamp\":\"2026-03-06T21:50:13Z\",\"type\":\"response_item\",\"payload\":{\"type\":\"message\",\"role\":\"user\",\"content\":\"# Context from my IDE setup:\\n\\n## Active file: src/main.ts\"}}\n",
+                "{\"timestamp\":\"2026-03-06T21:50:14Z\",\"type\":\"response_item\",\"payload\":{\"type\":\"message\",\"role\":\"user\",\"content\":\"Fix the login bug\"}}\n"
+            ),
+        )
+        .expect("write");
+
+        let meta = parse_session(&path).unwrap();
+        assert_eq!(meta.title.as_deref(), Some("Fix the login bug"));
+    }
+
     #[test]
     fn parse_session_falls_back_to_dir_basename() {
         let temp = tempdir().expect("tempdir");