Preserve deprecated docs links in prepare-release.

Author: frozenlib

.codex/skills/prepare-release/SKILL.md

@@ -30,7 +30,8 @@ In sandboxed Codex environments, `cargo +nightly -Zscript` may need approval bec
 4. If `cargo +nightly -Zscript` is unavailable, make the same edits manually.
    - Set `parse-display/Cargo.toml` package `version` to `<version>`.
    - Update `Cargo.lock`'s `parse-display` package version to `<version>`.
-   - Search docs and Rust doc comments for the previous parse-display version and update only parse-display version references, such as:
+   - Search docs and Rust doc comments for the previous parse-display version and update only active parse-display version references, such as dependency snippets and current-version docs links.
+   - Do not update docs.rs links for deprecated features. Deprecated feature documentation must keep linking to the older version where that deprecated feature is still documented.
 
 ```powershell
 rg -n '<old-version>|parse-display = "' README.md parse-display parse-display-with

.codex/skills/prepare-release/scripts/prepare_release.rs

@@ -276,19 +276,47 @@ fn update_docs(
 ) -> Result<(), String> {
     for path in doc_files(root)? {
         let text = read(&path)?;
-        let mut new_text = text.replace(
-            &format!("parse-display = \"{old_version}\""),
-            &format!("parse-display = \"{version}\""),
-        );
-        new_text = new_text.replace(
-            &format!("docs.rs/parse-display/{old_version}/"),
-            &format!("docs.rs/parse-display/{version}/"),
-        );
+        let new_text = update_doc_text(&text, old_version, version);
         write_if_changed(&path, new_text, dry_run, changed)?;
     }
     Ok(())
 }
 
+fn update_doc_text(text: &str, old_version: &str, version: &str) -> String {
+    let dependency_before = format!("parse-display = \"{old_version}\"");
+    let dependency_after = format!("parse-display = \"{version}\"");
+    let docs_before = format!("docs.rs/parse-display/{old_version}/");
+    let docs_after = format!("docs.rs/parse-display/{version}/");
+    let mut in_deprecated_section = false;
+
+    let lines = text
+        .lines()
+        .map(|line| {
+            let doc_line = markdown_text(line);
+            if doc_line.starts_with("## ") {
+                in_deprecated_section =
+                    doc_line.contains("Deprecated") || doc_line.contains("非推奨");
+            }
+
+            let mut line = line.replace(&dependency_before, &dependency_after);
+            if !in_deprecated_section {
+                line = line.replace(&docs_before, &docs_after);
+            }
+            line
+        })
+        .collect::<Vec<_>>();
+
+    finish(lines)
+}
+
+fn markdown_text(line: &str) -> &str {
+    line.trim_start()
+        .strip_prefix("///")
+        .or_else(|| line.trim_start().strip_prefix("//!"))
+        .unwrap_or(line)
+        .trim_start()
+}
+
 fn doc_files(root: &Path) -> Result<Vec<PathBuf>, String> {
     let mut files = Vec::new();
     collect_doc_files(root, root, &mut files)?;