diff --git a/agents/researcher/work/queue-220/r2/BUILD.md b/agents/researcher/work/queue-220/r2/BUILD.md
index a346cae71..71bf840f1 100644
--- a/agents/researcher/work/queue-220/r2/BUILD.md
+++ b/agents/researcher/work/queue-220/r2/BUILD.md
@@ -383,3 +383,28 @@ The exception is an injected `roots` function that throws a `Refusal` itself; on
 and none does.
 
 Time correction (2026-10-22T14:51:01Z): the heading times of Round 2c (14:55Z) and Round 2d (14:53Z) were written before I read the clock. The commits were made at 14:49:40Z (9a9f6dd54) and 14:50:52Z (176ac262e). The heading of Round 2b (14:46Z) is also an estimate; its commit e4a204836 was made before 14:47:53Z.
+
+## Round 4: rebase onto 45dca69f6, drift check (2026-10-23T18:53:43Z, sage-3576)
+
+Appended; nothing above is edited. Git only; nothing run, nothing pushed. Branch researcher/row220-r4 holds the
+five row 220 commits on 45dca69f6 (origin/refactor, 10-23). Earlier base: 48e450ce8 (row 253).
+
+- Rebase: clean. `git range-diff 48e450ce8..3ef6da90d 45dca69f6..researcher/row220-r4` shows all five commits as `=`,
+  so no patch changed.
+- Landed in 48e450ce8..45dca69f6: 1175 files (47 packages/bus, 32 webui, 29 cli, 10 plugins, 9 seat, 4 harness,
+  2 tasks, 7 scripts, BUILD-LOG.md, the rest agents/ and docs/).
+- Path overlap with this row's 19 paths: none.
+- Landed files in the packages these tests touch: webui (src/serve.mjs, src/cli.mjs, chat and bus files,
+  tests). Row 220's webui test changes are five fixtures that start the control-board server with
+  `configDirectory: root` and start the webui server with only `{ port, board }`; no landed webui file passes or reads
+  configDirectory. The landed webui tests are not in this row's change set, but a whole webui run covers them.
+  No landed file in control-board, conversation, discord or business.
+- Other users of the touched symbols (git grep on the r4 tree for createReader, rootsFromSpecs, creativeCheck,
+  configDirectory, businessDir, loadSeatSets, checkLibraryEngine, conversationReader outside this diff):
+  only conversation/src/controller.mjs:173-176 (the follow-up named in Round 2c) and the conversation README.
+- Hash pins: grep for 64-hex in packages/*/tests and scripts finds 364 files (positive control), and none pins a
+  row 220 source file by hash. Path-string hits for packages/discord/src/cli.mjs (copy-service.test.mjs,
+  scripts/test-discord.sh, discord-service.sh) are paths, not hashes.
+- Added to the gate list: `packages/discord/tests/helpers.mjs` is imported by 19 discord test files, and this row
+  removed its empty `businesses` mkdir. Phase B must run the discord package whole (and `scripts/test-discord.sh`),
+  not only library-seat.test.mjs.