Fix uv pylock rollback shape (#407, #408) (#512)

* Start fix for #407, #408

Assisted-by: Claude Code:claude-opus-5-5

* Add failing tests for uv pylock rollback shape

A uv pip compile pylock (no index key) refuses to roll back (#407),
and a restored pylock entry gets millisecond upload-time values where
uv writes whole seconds (#408).

Assisted-by: Claude Code:claude-opus-5-5

* Fix uv pylock rollback refusing and drifting

Hosted rollback, remove and the vendored takeover refused every
pylock.toml written by `uv pip compile`, because that command records
no `index` key and the restore only read the registry from one (#407).
Packages without an `index` whose files are all on PyPI now show the
registry, and the entry is restored without an `index` too.

A rolled-back pylock also never matched what uv writes: restored
`upload-time` values kept milliseconds, while uv writes whole seconds
in pylock files (#408). The restore now follows the lock's own
precision.

The real-uv hosted e2e lanes for `uv export` and `uv pip compile`
pylocks now lock a PyPI sibling and require a byte-exact rollback.

Assisted-by: Claude Code:claude-opus-5-5

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: mikolalysenko

crates/socket-patch-cli/CLI_CONTRACT.md

@@ -850,7 +850,7 @@ v5.0 replaces v4's per-purl reverts and whole-ledger reverse replay (`revert_rem
   * **vlt** — `vlt-lock.json`: slot [2] from the registry's `dist.integrity`, slot [3] per the lock's own convention (see the vlt hosted-mode contract); every hosted instance of the pin together.
   * **cargo** — `Cargo.lock` back on crates.io (source + the sparse index's checksum, `SOCKET_CRATES_INDEX`); every `Cargo.toml` declaration loses its `registry = "socket-patch-<uuid>"` pin (the shorthand the rewriter produced collapses back); the unreferenced `[registries.socket-patch-<uuid>]` block leaves the project cargo config. A declaration it cannot unpin refuses.
   * **golang** — the hosted `replace` and the socket module's go.sum lines go; the upstream module's two go.sum lines come back, hashed from the module proxy (`SOCKET_GOPROXY`, else `GOPROXY` / `GONOPROXY` / `GOPRIVATE` as go reads them) and cross-checked against the checksum database (`SOCKET_GOSUMDB_URL`, else `sum.golang.org` unless `GOSUMDB=off` / `GONOSUMDB` / `GOPRIVATE` say go would not ask it). A `replace` the user had before the hosted run is not recorded anywhere, so the restore lands on the plain upstream module.
-  * **pypi** — `Pipfile.lock`, `requirements.txt` (+ in-root `-r` includes), Hatch PEP 508 direct references (`pyproject.toml` / `hatch.toml`), `poetry.lock`, `pdm.lock`, `uv.lock`, PEP 723 script locks and PEP 751 `pylock*.toml` (+ the paired `pyproject.toml` / script metadata): hashes re-derived from PyPI's JSON API (`SOCKET_PYPI_JSON_API`). Refused: a `pdm.lock` without `cross_platform`, or a uv / script / pylock lock, whose release has a wheel that is not pure Python 3 (which files the lock keeps is not re-derivable); a uv lock whose options filter files (`exclude-newer`, `no-binary`, `no-build`), or whose other registry packages name no registry, several, or one other than PyPI's simple index; uv 0.2 `[[distribution]]` locks. A transitive `override-dependencies` entry hosted mode added is removed (`upstream_uv_override_removed`).
+  * **pypi** — `Pipfile.lock`, `requirements.txt` (+ in-root `-r` includes), Hatch PEP 508 direct references (`pyproject.toml` / `hatch.toml`), `poetry.lock`, `pdm.lock`, `uv.lock`, PEP 723 script locks and PEP 751 `pylock*.toml` (+ the paired `pyproject.toml` / script metadata): hashes re-derived from PyPI's JSON API (`SOCKET_PYPI_JSON_API`). Refused: a `pdm.lock` without `cross_platform`, or a uv / script / pylock lock, whose release has a wheel that is not pure Python 3 (which files the lock keeps is not re-derivable); a uv lock whose options filter files (`exclude-newer`, `no-binary`, `no-build`), or whose other registry packages name no registry, several, or one other than PyPI's simple index; a pylock whose other registry packages show neither an `index` nor (as `uv pip compile` writes them) only PyPI files with none, which restores the entry without an `index` too; uv 0.2 `[[distribution]]` locks. A restored pylock entry's `upload-time`s are whole seconds, as uv writes them, unless the lock's other entries show fractions. A transitive `override-dependencies` entry hosted mode added is removed (`upstream_uv_override_removed`).
   * **gem** — `Gemfile.lock` / `gems.locked` + `Gemfile` / `gems.rb`: the spec moves back into the upstream `GEM` section (or the Socket remote leaves a merged section), the `source "<patch registry>" do … end` block is undone, the `CHECKSUMS` entry is re-pinned from the rubygems.org compact index (`SOCKET_RUBYGEMS_URL`) and the `DEPENDENCIES` pin loses its `!`. The declaration's original constraint is not recorded, so it comes back as the exact pin `gem "<name>", "<version>"`. A transitive gem (one the manifest never declared) gets an appended block with a blank line before it; the restore removes that block, its blank line and the `DEPENDENCIES` entry, so the pair comes back byte for byte. An appended block with no blank line before it (written by a release before this one) can't be told apart from an in-place rewrite, so it still comes back as the exact pin. Refused: an ambiguous upstream section, an upstream remote other than rubygems.org.
   * **composer** — `composer.lock`: `dist` and the deleted `source` block from packagist's composer v2 metadata (`SOCKET_PACKAGIST_URL`). Refused unless the entry is packagist-sourced and packagist still serves the lock's `dist.reference` for the version.
   * **maven** — `pom.xml` (the `-socket.<hex8>` version suffix, the added `<repository>` / `<dependencyManagement>` entry) and the `.mvn/maven.config` / `.mvn/checksums/checksums.sha256` lines hosted mode writes: **no network**, so it restores under `--offline` too. `.mvn` files holding anything else keep the resolver lines (`maven_trusted_checksums_left`).

crates/socket-patch-cli/tests/vex_e2e_common/uv.rs

@@ -688,7 +688,10 @@ struct Built {
 
 /// Build the lane's project with the real uv (network: PyPI). `Err` is a
 /// skip reason (PyPI unreachable, fixture command failed).
-fn build(uv: &Uv, lane: Lane, tmp: &Path) -> Result<Built, String> {
+/// `mode` hosted: the uv pylock lanes also lock a pure-Python PyPI sibling
+/// (`idna`), which shows the hosted rollback the lock's registry and
+/// artifact shape.
+fn build(uv: &Uv, lane: Lane, mode: Mode, tmp: &Path) -> Result<Built, String> {
     let proj = tmp.join("proj");
     std::fs::create_dir_all(&proj).unwrap();
     let cache = tmp.join("uv-cache");
@@ -754,10 +757,16 @@ fn build(uv: &Uv, lane: Lane, tmp: &Path) -> Result<Built, String> {
         Lane::ExportPylock => {
             let src = tmp.join("export-src");
             std::fs::create_dir_all(&src).unwrap();
+            let deps = match mode {
+                Mode::Hosted => "\"six==1.16.0\", \"idna==3.7\"",
+                Mode::Vendored => "\"six==1.16.0\"",
+            };
             std::fs::write(
                 src.join("pyproject.toml"),
-                "[project]\nname = \"uv-vex-capstone\"\nversion = \"0.1.0\"\n\
-                 requires-python = \">=3.9\"\ndependencies = [\"six==1.16.0\"]\n",
+                format!(
+                    "[project]\nname = \"uv-vex-capstone\"\nversion = \"0.1.0\"\n\
+                     requires-python = \">=3.9\"\ndependencies = [{deps}]\n"
+                ),
             )
             .unwrap();
             need(uv.run_py(&src, &["lock"], &cache), "uv lock")?;
@@ -773,7 +782,13 @@ fn build(uv: &Uv, lane: Lane, tmp: &Path) -> Result<Built, String> {
             pylock_sync(uv, &proj, &cache)?;
         }
         Lane::CompilePylock => {
-            std::fs::write(proj.join("requirements.in"), "six==1.16.0\n").unwrap();
+            // Hosted: `idna` is a sibling with no `index` (uv pip compile
+            // writes none).
+            let reqs = match mode {
+                Mode::Hosted => "six==1.16.0\nidna==3.7\n",
+                Mode::Vendored => "six==1.16.0\n",
+            };
+            std::fs::write(proj.join("requirements.in"), reqs).unwrap();
             need(
                 uv.run_py(
                     &proj,
@@ -1171,7 +1186,7 @@ pub fn run_lane(suite: &str, uv: &Uv, mode: Mode, lane: Lane) {
         return;
     }
     let tmp = tempfile::tempdir().unwrap();
-    let built = match build(uv, lane, tmp.path()) {
+    let built = match build(uv, lane, mode, tmp.path()) {
         Ok(b) => b,
         Err(why) => {
             skip(suite, &format!("{}: {why}", report.what("setup")));
@@ -1611,6 +1626,11 @@ pub fn run_lane(suite: &str, uv: &Uv, mode: Mode, lane: Lane) {
         ),
     };
     if mode == Mode::Hosted {
+        // The uv pylock lanes lock a PyPI sibling, which shows the registry
+        // (an `index`, or for `uv pip compile` PyPI files with none, #407)
+        // and the artifact shape, so they restore to the bytes uv wrote
+        // (#408).
+        let byte_exact = matches!(lane, Lane::ExportPylock | Lane::CompilePylock);
         let env: Value = serde_json::from_slice(&out.stdout)
             .unwrap_or_else(|e| panic!("{}: ({e})\n{}", report.what("revert"), dump(&out)));
         let still_wired =
@@ -1624,15 +1644,28 @@ pub fn run_lane(suite: &str, uv: &Uv, mode: Mode, lane: Lane) {
                     report.what("revert"),
                     dump(&out)
                 );
-                for (f, _) in &built.registry {
+                for (f, bytes) in &built.registry {
                     assert!(
                         !still_wired(f),
                         "{}: {f} still names the hosted patch",
                         report.what("revert")
                     );
+                    if byte_exact {
+                        assert_eq!(
+                            String::from_utf8_lossy(&std::fs::read(proj.join(f)).unwrap()),
+                            String::from_utf8_lossy(bytes),
+                            "{}: {f} not byte-restored",
+                            report.what("revert")
+                        );
+                    }
                 }
                 report.row("revert", "restored to the upstream registry entry");
             }
+            _ if byte_exact => panic!(
+                "{}: a uv pylock must restore:\n{}",
+                report.what("revert"),
+                dump(&out)
+            ),
             _ => {
                 let error = env["hosted"]["failed"][0]["error"]
                     .as_str()