Record the installer divergence, and why the dead block stays

docs/handoff/20260815-after-v1.md

@@ -134,3 +134,54 @@ Each cost a cycle today.
   Pin the failure mode, not the value.
 - `git push` printing `branch set up to track` does not mean a commit was
   pushed. Read `git ls-remote` back.
+
+## After v1.0.1 — the installer divergence
+
+v1.0.1 shipped the five distribution fixes and its controls inverted. What
+followed came from looking at what those fixes touched.
+
+**#693 — the hook pinned a release.** `commitlore.bin` recorded
+`<data-root>/v<version>/dist/commitlore.mjs`, so an upgrade left a repository
+validating commits with the build it was installed from. Three repositories on
+the first machine to upgrade were doing that — this one among them, through two
+releases. Fixed by `install.sh` maintaining `<data-root>/current` and hooks
+recording it: still an absolute path to a `.mjs`, so the recorded interpreter can
+launch it, but naming no release.
+
+The obvious repair was tried and is wrong. Recording the `bin` wrapper made hooks
+fail under the restricted `PATH` a hook actually runs in, because a wrapper is a
+shell script and cannot be launched with a recorded interpreter. That is #694,
+closed with the measurement so nobody repeats it.
+
+**#697 — the two installers do different things.** Deleting `install.sh`'s dead
+host block revealed that `install.ps1` installs the Codex plugin and
+`install.sh` never did: its `wire_codex_plugin` was reachable only from
+`wire_codex`, which nothing calls. Windows users got a plugin layer the others
+did not.
+
+The plugin step now lives in the enumeration both installers call. The rest of
+the divergence is mapped host by host on the issue.
+
+## The trap that produced three issues
+
+`test/agent-configs.test.ts` asserted host config paths were **present in
+`install.sh`**. Presence, not reachability. `T-1121` asserted the same sentences
+appear in both installers so they "cannot drift" — and the parity was holding
+between a live script and a dead block.
+
+Both assertions passed for years while the shell wired nothing. #689, #697 and
+half of #660 were invisible underneath them.
+
+An assertion that names a file is not an assertion that the file does anything.
+
+## Why #691 is still open
+
+`install.sh`'s 291 dead lines look deletable and are not, yet. `install.ps1`'s
+wiring is **not** their dead twin: it delegates at line 817 **and** wires hosts
+itself from line 1089, so Windows does every host twice. Deleting the POSIX copy
+alone breaks `T-1121`, which is the test doing its job.
+
+The Codex gap proves the two sides are not equivalent, so the order is fixed:
+confirm the enumeration performs each row, remove the duplicate, and only then
+the dead block. Never the reverse — that removes a step nothing else performs, on
+a platform the author cannot run.