feat(index): Add unstable pubtime field

Author: epage

crates/cargo-test-support/src/publish.rs

@@ -228,6 +228,7 @@ pub(crate) fn create_index_line(
     yanked: bool,
     links: Option<String>,
     rust_version: Option<&str>,
+    pubtime: Option<&str>,
     v: Option<u32>,
 ) -> String {
     // This emulates what crates.io does to retain backwards compatibility.
@@ -251,6 +252,9 @@ pub(crate) fn create_index_line(
     if let Some(rust_version) = rust_version {
         json["rust_version"] = serde_json::json!(rust_version);
     }
+    if let Some(pubtime) = pubtime {
+        json["pubtime"] = serde_json::json!(pubtime);
+    }
 
     json.to_string()
 }

crates/cargo-test-support/src/registry.rs

@@ -578,6 +578,7 @@ pub struct Package {
     links: Option<String>,
     rust_version: Option<String>,
     cargo_features: Vec<String>,
+    pubtime: Option<String>,
     v: Option<u32>,
 }
 
@@ -1243,6 +1244,7 @@ fn save_new_crate(
         new_crate.links,
         new_crate.rust_version.as_deref(),
         None,
+        None,
     );
 
     write_to_index(registry_path, &new_crate.name, line, false);
@@ -1273,6 +1275,7 @@ impl Package {
             links: None,
             rust_version: None,
             cargo_features: Vec::new(),
+            pubtime: None,
             v: None,
         }
     }
@@ -1460,6 +1463,12 @@ impl Package {
         self
     }
 
+    /// The publish time for the package in ISO8601 with UTC timezone (e.g. 2025-11-12T19:30:12Z)
+    pub fn pubtime(&mut self, time: &str) -> &mut Package {
+        self.pubtime = Some(time.to_owned());
+        self
+    }
+
     /// Sets the index schema version for this package.
     ///
     /// See `cargo::sources::registry::IndexPackage` for more information.
@@ -1536,6 +1545,7 @@ impl Package {
                 self.yanked,
                 self.links.clone(),
                 self.rust_version.as_deref(),
+                self.pubtime.as_deref(),
                 self.v,
             )
         };

crates/cargo-util-schemas/index.schema.json

@@ -68,6 +68,13 @@
         "null"
       ]
     },
+    "pubtime": {
+      "description": "The publish time for the package.  Unstable.\n\nIn ISO8601 with UTC timezone (e.g. 2025-11-12T19:30:12Z)",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
     "v": {
       "description": "The schema version for this entry.\n\nIf this is None, it defaults to version `1`. Entries with unknown\nversions are ignored.\n\nVersion `2` schema adds the `features2` field.\n\nVersion `3` schema adds `artifact`, `bindep_targes`, and `lib` for\nartifact dependencies support.\n\nThis provides a method to safely introduce changes to index entries\nand allow older versions of cargo to ignore newer entries it doesn't\nunderstand. This is honored as of 1.51, so unfortunately older\nversions will ignore it, and potentially misinterpret version 2 and\nnewer entries.\n\nThe intent is that versions older than 1.51 will work with a\npre-existing `Cargo.lock`, but they may not correctly process `cargo\nupdate` or build a lock from scratch. In that case, cargo may\nincorrectly select a new package that uses a new index schema. A\nworkaround is to downgrade any packages that are incompatible with the\n`--precise` flag of `cargo update`.",
       "type": [

crates/cargo-util-schemas/src/index.rs

@@ -46,6 +46,10 @@ pub struct IndexPackage<'a> {
     /// can be `None` if published before then or if not set in the manifest.
     #[cfg_attr(feature = "unstable-schema", schemars(with = "Option<String>"))]
     pub rust_version: Option<RustVersion>,
+    /// The publish time for the package.  Unstable.
+    ///
+    /// In ISO8601 with UTC timezone (e.g. 2025-11-12T19:30:12Z)
+    pub pubtime: Option<String>,
     /// The schema version for this entry.
     ///
     /// If this is None, it defaults to version `1`. Entries with unknown

src/cargo/ops/cargo_package/mod.rs

@@ -1229,6 +1229,7 @@ impl<'a> TmpRegistry<'a> {
             yanked: None,
             links: new_crate.links.map(|x| x.into()),
             rust_version: None,
+            pubtime: None,
             v: Some(2),
         })?;
 

src/cargo/sources/registry/index/mod.rs

@@ -674,6 +674,7 @@ impl IndexSummary {
                     cksum: Default::default(),
                     yanked: Default::default(),
                     links: Default::default(),
+                    pubtime: Default::default(),
                 };
                 let summary = index_package_to_summary(&index, source_id)?;
                 (index, summary, false)