Hosted gem rollback / remove strips the DEPENDENCIES ! of a gem the user declared inside a source "https://rubygems.org" do block, so every frozen install fails after the unwind #1056

[agent] Found by the scheduled Bundler (RubyGems) bug-hunt routine (ledger #316).

Summary

Bundler marks a dependency declared inside a source … do block with ! in the lock's DEPENDENCIES (colorize (= 0.8.1)!), even when that block's source is rubygems.org. The hosted scan of such a gem works: it nests the patch-registry block inside the user's block, and the fresh frozen install gets the patched bytes. The unwind (rollback, or remove <purl>) then restores the Gemfile byte for byte, so the declaration is back inside the user's source "https://rubygems.org" do block. But the unwind always drops the ! from the lock's DEPENDENCIES line. The restored pair no longer matches what Bundler writes, so BUNDLE_FROZEN=true bundle install fails with exit 16 ("Your lockfile needs to be updated, but it can't be because frozen mode is set"). rollback still reports success with hosted.reverted: [pkg:gem/colorize@0.8.1].

Impact

After undoing a patch, every CI or deployment (frozen) install of the project breaks until someone runs an unfrozen bundle install and commits the lock. The unwind is supposed to give back the original, installable pair.

Repro (Linux, Ruby 3.3.6, Bundler 4.0.22 or 2.6.9 with bundle lock --add-checksums)

Patch API and patch registry mocked on loopback (the run-13 mock from ledger #316); rubygems.org is the real upstream.

mkdir app && cd app
printf 'source "https://rubygems.org"\n\ngem "rake"\nsource "https://rubygems.org" do\n  gem "colorize", "0.8.1"\nend\n' > Gemfile
bundle lock && cp Gemfile.lock /tmp/orig.lock    # DEPENDENCIES: colorize (= 0.8.1)!
socket-patch scan --mode hosted --yes --api-url $MOCK --org org --api-token fake
BUNDLE_FROZEN=true BUNDLE_PATH=vb bundle install  # exit 0, patched bytes (OK)
socket-patch rollback --api-url $MOCK --org org --api-token fake --patch-server-url $MOCK
diff /tmp/orig.lock Gemfile.lock
#   <   colorize (= 0.8.1)!
#   ---
#   >   colorize (= 0.8.1)
git diff Gemfile                                  # empty: the Gemfile came back exactly
BUNDLE_FROZEN=true BUNDLE_PATH=vb2 bundle install # exit 16

socket-patch remove pkg:gem/colorize@0.8.1 leaves the same diff, and a frozen install then fails with exit 16 too.

Expected vs actual

• Expected: CLI_CONTRACT.md's "Hosted unwind coverage" gem row says the unwind undoes the source "<patch registry>" do … end block and "the pair comes back". The ! should only be dropped when the restored declaration no longer sits in a user source block (the case where hosted mode added it). Here the declaration's own block still pins the source, so the original ! must stay, and the lock should come back byte-identical to the pre-scan one.
• Actual: the ! is always removed (the row says "the DEPENDENCIES pin loses its !" without exception), which leaves a pair that Bundler's frozen mode rejects.

Matrix

macOS and Windows weren't probed. The lock surgery is OS-independent.

First bad version

Not bisected. This is current main d47eab3; the v5 upstream restore introduced the hosted unwind.

Suspect code

crates/socket-patch-core/src/patch/redirect/upstream/gem.rs:354: for a non-transitive gem, entry.strip_suffix('!') unconditionally rewrites the DEPENDENCIES line to the unpinned form. It doesn't check whether the restored Gemfile still declares the gem inside a source … do block (or with a source: / git: / path: option), and in that case Bundler keeps the !.

Backlog review — 2026-10-08

Priority: P1 → P2. A rubygems source-block dependency loses its marker and frozen installation fails after rollback; visible conditional breakage.