docs: name pull request 4 as the subject to land

subject.md

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+# Subject
+
+Repository: `atlantic-blue/transcript`. I fetched before I read. `origin/main` is at `3b5f6cc`.
+
+## The pull request to land
+
+- Number: 4
+- Title: fix: report what the platform actually answered instead of a missing video
+- Head branch: `diagnose-the-boundary-and-report-the-real-cause`
+- Head commit: `84d9fe37c3414e82dc8937a7046a626cc590d8c0`
+- Base branch: `main`
+- Conflicts with main: no
+- Checks that are not passing: `plan and apply`
+
+It is the older of the two open pull requests. One check on its head commit failed. It qualifies on
+the failing check alone.
+
+## The failing check is hidden from the usual command
+
+`gh pr checks 4` prints two checks, `code` and `infrastructure`. It says both pass, and it exits 0.
+It does not print `plan and apply`. The pull request summary agrees: the check list holds two names.
+
+The check is on the commit. Read the commit to see it:
+
+```
+gh api repos/atlantic-blue/transcript/commits/84d9fe37/check-runs \
+  --jq '.check_runs[] | "\(.name) \(.conclusion)"'
+```
+
+That answers with three names. `plan and apply` is `failure`.
+
+The trigger is the reason. The `deploy` workflow runs on a push to `main` and on a manual start. It
+does not run on a pull request. Run 33387270234 was started by hand on the branch, so GitHub keeps
+it out of the pull request summary. An absent check reads the same as a passing one.
+
+https://github.com/atlantic-blue/transcript/actions/runs/33387270234/job/99472620061
+
+## What the failing check says
+
+The deploy applied. The last step opened the page and read it. The page answered 502 eight times
+over four minutes. The body said "The platform refused this page, not your video".
+
+## This pull request does not cause the failure
+
+Every `deploy` run in this repository failed, on `main` as well as on this branch. The runs on
+`main` at `3b5f6cc`, `75b62fb` and `e61e38d` all failed.
+
+The pull request says why. The platform refuses the address the function calls from. It refuses
+with a bot check, at the watch page, before the proof of origin work starts. The pull request makes
+the page report that cause. Before it, the page answered 404 and said the video was missing.
+
+The pull request description states that the deploy check stays red while the product cannot read a
+transcript. So do not expect `plan and apply` to go green when you land this. Getting the caption
+text is the open problem the project context already names.
+
+## The repository has no required checks
+
+`repos/atlantic-blue/transcript/branches/main/protection` answers 404, "Branch not protected". The
+ruleset list is empty. No check is required and no check blocks a merge. `plan and apply` is a check
+that failed, not a gate.
+
+## The other open pull request, and why I did not pick it
+
+- Number: 5
+- Title: docs: name the pull request to land
+- Head branch: `docs-name-the-pull-request-to-land`
+- Head commit: `46b9460a1d60528647fa19f8f691d36ee9155c07`
+- Conflicts with main: no
+- Checks that are not passing: none
+
+It is newer than 4. It does not conflict, and no check on it failed. So it does not qualify. It
+carries two check runs, `code` and `infrastructure`. Both passed. The `deploy` workflow never ran on
+its head commit.
+
+Pull request 5 is the output of an earlier round of this same task, and its `subject.md` also names
+pull request 4. It is still open. Both files add `subject.md` at the root, so whichever one merges
+second will conflict with the first.
+
+## The exclusions I checked
+
+- Neither pull request is a draft. `draft` is false on both.
+- Both target `main`. Both come from this repository, not a fork. So neither head branch is the base
+  of the other, and landing 4 breaks no child.
+- Neither conflicts. `git merge-tree --write-tree origin/main <head>` exits 0 for both and reports no
+  conflict. I ran this locally because GitHub answered `mergeable=null` on a later read, which is the
+  value it gives while it recomputes.
+- There are only two open pull requests. `repos/atlantic-blue/transcript/pulls?state=open` returns a
+  list of length 2.
+
+## What I did not do
+
+I changed nothing in pull request 4 and nothing on `main`. This step reads and records.