The shim judges what a forge holds of the text: the merge message it composes, the lines an edit adds, and a title set through api or glab mr merge

[HackingGate]

Part of #331 (items B, C, E and F). Items A and D are in a separate pull request.

Special characters are spelt as codepoints throughout, because the installed gh shim may predate #330.

What changed

• B. collect_api (src/shim.rs) maps a gh api / glab api field whose key is title or commit_title to subject kind "title" (API_TITLE_KEYS, a closed list read off the key, never off the path). Every other field stays prose. --input JSON is unchanged: every string value is still prose.
• C. policy/principles.toml: the glab table matches mr:merge, with a [[shim.verbs]] entry. Its message_flags = ["-m", "--message", "--squash-message"] judges the first line as a title and the rest as prose, and editor = "forge" says when GitLab composes the message unread. Both fields are new; see the review section. The entry's text_flags list is empty, so -d (here --remove-source-branch, a switch) cannot swallow the next word.
• E. On gh pr merge --squash or --merge, with no editor path and some part of the message not given, the shim asks GitHub what it would compose and judges that text: the subject as a title, the body as prose. It asks with gh pr view [sel] [-R repo] --json id, then gh api graphql for viewerMergeHeadlineText / viewerMergeBodyText. If the forge cannot be asked, the shim exits 2 and the merge does not run.
• F. On gh issue edit / gh pr edit with --body or --body-file, the shim asks for the stored body (gh issue view / gh pr view --json body, once per selector, against the -R the command names). Only prevent-unusual-unicode is then judged on the lines the edit adds; every other checker still sees the whole body. If the forge cannot be asked, the shim exits 2, and so does an option it does not know on that verb.
• Both forge questions are asked only when a rule that is not bypassed will read the answer. FORGE_HELD declares the three verbs as gh grammar, with each verb's switches. Operands reads the selector, the method and -R from argv, including short clusters like -sd.
• docs/REFERENCE.md: updated the editor table row, the gh api field row, the gh pr merge editor paragraph, and the subject-vs-prose paragraph.

Decisions on the Open items

E: fetch the composed message and judge it. Do not require --subject/--body. The issue's Open note says GitHub does not expose its composition rule. It does expose the result: PullRequest.viewerMergeHeadlineText(mergeType:) and viewerMergeBodyText(mergeType:) are what gh pr merge itself reads to seed "Edit commit message". So the shim judges the message GitHub would write under the repository's own squash/merge settings, and does not reimplement the composition rule. Reasons for this choice over requiring the flag:

• It keeps the shim's usual contract: it reads what will be published, and a forge that cannot be asked is exit 2, never a silent pass.
• It does not change what gh pr merge --squash means at the shim. Requiring the flag would refuse every ordinary merge, including the one that surfaced this.
• Only the part nobody gave is asked for, so --subject plus --body costs no round trip.

Limits:

• --rebase writes no message of GitHub's, and --auto without a method names no merge to ask about. Both keep the existing "not checked" line.
• --auto --squash is judged on what GitHub would compose now; the merge itself happens later.
• glab mr merge with no message is not fetched (GitLab composes it). It runs, and because the verb is editor = "forge" the shim prints the "forge composes ... not checked" notice first.

F: judge the lines the edit adds, diffed against the stored body.

• Lines are compared as a multiset: a line the forge holds once and the edit carries twice counts as added once.
• A trailing \r is ignored, because GitHub stores web-edited bodies with CRLF.
• A changed line counts as added, whole. So an invisible on the line being edited is still read, while one on an untouched line no longer blocks the edit.
• A line carrying a bidi embedding, override or isolate (U+202A to U+202E, U+2066 to U+2069) is judged even when unchanged, because it reorders what the edit writes after it.
• Only the body flags' subjects (-b, --body, -F, --body-file) are narrowed. A title is judged whole even under uphold init's table, which reads --title as text, and a title-only edit does not ask the forge.
• Only prevent-unusual-unicode reads the added lines (Subject::added / Published::added). Patterns, require_regexp, exec checkers and the other guards see the whole body, as before this PR.
• A forge that cannot be asked is exit 2.

Done when

• B. a_title_set_through_the_api_is_judged_as_the_title_it_is (tests/shim_cli.rs):
  • gh api -X PATCH repos/o/r/pulls/1 -f title=<Latin word with U+0430> and gh api -X PUT repos/o/r/pulls/1/merge -f commit_title=<same> are both refused, naming CYRILLIC SMALL LETTER A, and the stub never runs.
  • -f body=<same> runs.
• C. this_repositorys_own_glab_table_reads_the_merge_message, which drives this repository's own glab table:
  • glab mr merge 1 --squash-message <text with U+202E> is refused, and so are the -m and --message forms. The stub never runs.
  • --squash-message <Latin word with U+0430> is refused as a title.
  • glab mr merge 1 with no message runs.
  • -d -s --squash-message "Fix it" runs, and -d does not swallow the message.
• E. (fetch option)
  • a_squash_merge_whose_composed_message_hides_a_bidi_override_is_refused: a forge stub composing a squash body with U+202E refuses gh pr merge 1 --squash, and a composed subject with U+0430 is refused as a title.
  • a_squash_merge_whose_forge_cannot_be_asked_is_exit_two_and_never_runs: an unreachable stub gives exit 2. With -t and -b both given, nothing is asked and the merge runs.
  • a_squash_merge_with_no_message_reads_the_one_the_forge_composes: covers -sd, --merge and the body-only case.
• F.
  • an_edit_is_judged_on_the_lines_it_adds_to_the_body_the_forge_stores: gh issue edit 1 --body-file <file> over a stored body (stubbed gh issue view --json body, CRLF) that already carries U+200B runs when the edit adds plain text. The same edit adding U+202E is refused. Changing the line that carries U+200B is refused.
  • an_edit_whose_stored_body_cannot_be_asked_for_is_exit_two_and_never_runs: an unreachable forge gives exit 2.
  • a_pull_request_edit_asks_about_the_repository_it_names: covers --repo o/r --add-label bug 7.

Unit tests in src/shim.rs: an_edit_adds_the_lines_the_stored_body_does_not_hold_counted and the_operands_of_a_verb_are_read_with_its_own_switches. All tests stub the forge (GH_FORGE_STUB); none uses the network.

Changed existing tests

• this_repositorys_own_merge_opens_no_editor_and_says_the_forge_message_was_not_checked is renamed ..._and_reads_the_message_the_forge_composes. It now asserts that the composed message is read.
• The --squash form of a_merge_that_opens_no_editor_says_the_forge_message_was_not_checked moved to the new E test. The method-less form still asserts the notice.
• gh_workspace and gh_stub_workspace now install the forge stub.

Review fixes (second commit, 2ee90c0)

• M1. Each gh verb the shim asks the forge about (issue edit, pr edit, pr merge) now carries its whole option grammar from gh 2.102 help: switches and value-taking options are both listed. That includes issue edit's --remove-parent and --remove-type. An option in neither list is exit 2 rather than guessed at. This applies only where the text depends on it: an edit that resubmits a body, or a merge whose message has to be fetched. Tests: every_issue_an_edit_names_is_asked_about_whichever_switch_sits_between_them (selectors 5 and 6 around each switch, both asked) and an_edit_carrying_an_option_the_shim_does_not_know_is_exit_two_and_never_runs. A unit test runs every listed switch between two selectors.
• L1. Stored lines with a bidi control are always judged. Test: a_stored_bidi_override_is_judged_when_an_edit_writes_beneath_it, plus a case in the added_lines unit test.
• L2. Narrowing applies to prevent-unusual-unicode alone. Test: only_the_invisible_character_guard_is_narrowed_to_what_an_edit_adds, where an exec checker on gh pr edit --body sees the kept lines.
• L3. An empty --subject "" counts as not given, so the forge is asked for it. The third commit corrects the body half against gh's source: an empty --body "" is the body, not composed.
• L4. One short-option parser, read_cluster, reads clusters and attached values (-st X, -bX). After the third review this is scoped to the three forge-held verbs only; see "Scoped down" below. gh pr merge 1 -st <U+202E> -b ok is refused and does not claim the subject was read from the forge.
• L5. -f/--raw-field sends @file literally, so only -F/--field reads the file. That reading was pre-existing behaviour, now fixed. Test: a_raw_field_is_sent_as_written_and_only_a_typed_one_reads_its_file. GitLab's squash_commit_message and merge_commit_message fields are judged as a message. Test: a_gitlab_merge_message_field_is_a_subject_line_and_a_body. The docs now say that --input JSON is prose in every value, and which keys are titles on which forge (commit_title is GitHub-only).
• L6. New message_flags (table and per-verb), with the first line judged as a title and the rest as prose. New editor = "forge", which prints the "forge composes ... not checked" notice when no message is given. Both are used on glab mr merge. Test: a_glab_merge_message_is_a_subject_line_and_a_body.

Nothing from the review was deferred.

Note for reviewers: an installed uphold older than this branch cannot parse editor = "forge". Its git shim therefore refuses git inside this worktree, which is the known shim version skew. The second commit and push were made with /usr/bin/git directly, so every hook still ran.

Second review fixes (third commit, acdb2a7)

• MEDIUM-1 / MEDIUM-2. read_cluster now follows pflag's parseSingleShortArg, checked against spf13/pflag flag.go, at whichever letter takes the value:

  • = followed by at least one character gives what follows the = (-b=X, -st=X, -iF=k=@f);
  • anything else after the letter is the value whole (-bX, and -b=, whose value is =);
  • nothing after the letter means the value is the next word;
  • a switch spelt -s=false is off.

  Tests: -b=, -st=X, -s=false and -iF=k=@f cases in the read_cluster unit test. an_empty_attached_value_is_the_sign_and_never_the_next_word covers gh pr create -b= -t <U+0430 word>, gh issue edit 5 -t= 6 -b ... (asks about Let a text-capable guard stand in front of a command #6), gh pr merge 7 -st=WIP x, gh pr merge 7 -s -b= -t "WIP x" (judged as given, forge not asked) and gh api ... -iF=body=@notes.md (file read).

• MEDIUM-3. Narrowing and the stored-body fetch now apply only to the body flags' subjects (HeldVerb::body_flags, found through the new Collected::flagged). Test: a_title_is_not_narrowed_against_the_stored_body_under_uphold_inits_table. It drives uphold init's own table: a title equal to a stored U+200B line is refused without asking the forge, and the body beside it is still narrowed.

• LOW-1. I checked gh v2.102.0 pkg/cmd/pr/merge. http.go sends commitHeadline only when commitSubject != "". merge.go sets BodySet whenever --body or --body-file is given, and http.go then sends commitBody even if it is empty. The shim now matches, with the source cited in the code comment and the docs. Test: an_empty_subject_is_composed_by_the_forge_and_an_empty_body_is_the_body (renamed from the second commit's test).

• LOW-2. This repository's gh table no longer reads -d/--description as text. -d is --draft (a switch) on pr create and release create, and --description exists on none of the matched verbs. gist create has its own entry reading -d/--desc with editor = "never". Test: draft_is_a_switch_on_create_and_the_text_after_it_is_read covers pr create -d -t, release create -d -n, -dn, and gist create -d / --desc.

• LOW-3. On the three FORGE_HELD verbs, the collector reads an option the table does not name with gh's own arity. Test: an_option_the_table_does_not_name_takes_the_value_gh_gives_it (-A -b -t WIP merge is refused on the subject).

• LOW-4. A message flag's body keeps its place in the message, so findings carry message line numbers. Test: a_finding_in_a_message_body_is_reported_by_its_line_in_the_message (text:3:).

Nothing from the second review was deferred. The third commit was made and pushed with /usr/bin/git, so every repository hook ran and nothing was bypassed with UPHOLD_ALLOW.

Scoped down (fourth commit, ba67ec5)

The third review found a HIGH regression from the second commit. collect_flags split every short option the table did not name whole letter by letter, on every gh and glab verb, guessing the arity of letters nothing named. A value's letters were then read as options, so text went out unread with exit 0:

• gh pr create -Bmain -t "WIP x": the n of main read as --notes and took the -t as its value.
• gh issue create -lalert -t ..., -ab -t ... and glab mr create -lbot -t ...: the title was not read.
• -lwip: its w read as --web, and the shim stood down from the editor.

At the user's direction this was scoped down rather than given a complete grammar for every verb:

• Cluster parsing outside the three forge-held verbs is removed. collect_flags splits a short word only on gh issue edit, gh pr edit and gh pr merge, whose whole option grammar (FORGE_HELD, gh 2.102) the shim carries. On those verbs it keeps the pflag value rule and gh's arity for options the table does not name, and a letter in neither the table nor the grammar is exit 2.
• Everywhere else the base (99e23fc) behaviour is back. On every other gh/glab verb, and in gh api / glab api, a word the table does not name whole is skipped whole and never split. That fixes the repros above. Nothing reads less than at 99e23fc, where -bX, -st X, -ftitle=X and -iF=k=@f were unknown words too.
• The resulting gap is pre-existing and the same as base. On those verbs a short-option cluster or an attached value is not read. docs/REFERENCE.md says so plainly, and it is left for a follow-up issue.
• LOW from the third review. A narrowed edit now reports the body's line numbers: added_lines keeps every line in place, empty where the edit kept it.

Tests:

• elsewhere_an_option_nothing_names_is_skipped_whole_and_the_text_after_it_is_read covers every repro above. Each is refused, under a test table and under this repository's own table. -Bmain, -Hfeat and -lbug in ordinary use run.
• a_short_cluster_on_a_forge_held_verb_is_read_as_the_command_reads_it (cluster forms, and an unknown letter exiting 2) replaces a_short_cluster_or_an_attached_value_is_read_as_the_command_reads_it.
• a_finding_in_a_narrowed_edit_is_reported_by_its_line_in_the_body checks the line number is text:3:3.
• Removed cases:
  • from the replaced test: gh pr create -bX, gh api -XPATCH -ftitle=X, glab mr merge -mX / -sm X;
  • from an_empty_attached_value_is_the_sign_and_never_the_next_word: the gh api -iF=... case;
  • from draft_is_a_switch_on_create_and_the_text_after_it_is_read: the gh release create -dn case.

The commit was made and pushed with /usr/bin/git, so every repository hook ran and nothing was bypassed with UPHOLD_ALLOW.

https://claude.ai/code/session_01QJkWXa2HxJ6q9TMNAGSNv4

[coderabbitai]

📝 Walkthrough

Walkthrough

The shim now parses whole commit-message inputs and short-option clusters, checks added lines in edited issue and pull-request bodies, and fetches applicable GitHub-held text for checking. GitLab merge-message flags and API fields are also collected and classified.

Changes

Forge message checks

Layer / File(s)	Summary
Message inputs and option parsing src/shim.rs, policy/principles.toml, docs/REFERENCE.md, tests/shim_cli.rs	CLI and API parsing recognizes title and whole-message inputs, handles short-option clusters, and applies the GitLab merge-message configuration. Tests cover message splitting, API fields, and GitLab flags.
Added-text guard inputs src/guard/mod.rs, src/text.rs, src/shim.rs, tests/shim_cli.rs	Published text carries optional added text. The unusual-Unicode guard checks that portion when present; other guards continue to receive the full text. Tests cover added-line comparisons and checker inputs.
Fetch and check forge-held text src/shim.rs, docs/REFERENCE.md, tests/shim_cli.rs	For applicable edits and GitHub merge operations, the shim fetches stored or composed text and checks it. Lookup failures refuse the operation. Tests cover edit comparisons, merge-message checks, and forge-query failures.

Priority: ➖ Normal

Estimated code review effort: 4 (Complex) | ~60 minutes

Change: Feature

Sequence Diagram(s)

sequenceDiagram
  participant Caller
  participant Shim
  participant gh
  participant text_refusal
  Caller->>Shim: Invoke an edit or merge command
  Shim->>gh: Query stored body or composed merge text
  gh-->>Shim: Return requested text or query failure
  Shim->>text_refusal: Check collected and fetched text
  text_refusal-->>Shim: Return refusal or allow result
  Shim->>gh: Run command when checks pass

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Merge Risk: 🟡 Moderate · up to 2ee90

The new short-option parsing can misread commands such as gh pr create -lbug as already supplying a body. The text then typed into the editor is published without the usual checks. Fix this before merging; the remaining forge-message checking changes appear consistent.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage		Docstring coverage is 94.94% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 79 functions across 4 files. (2 skipped: 2 …
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title accurately describes the main changes: forge-composed merge messages, added lines in edited bodies, and title handling through API or glab mr merge. It is longer than necessary but remains…

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Codecov Report

❌ Patch coverage is 95.87786% with 27 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.27%. Comparing base (99e23fc) to head (b03ca2b).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/shim.rs	95.83%	27 Missing ⚠️

❌ Your patch status has failed because the patch coverage (95.87%) is below the target coverage (100.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #333      +/-   ##
==========================================
+ Coverage   94.22%   94.27%   +0.05%     
==========================================
  Files          46       46              
  Lines       21924    22566     +642     
==========================================
+ Hits        20658    21275     +617     
- Misses       1266     1291      +25     

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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Inline comments:
Review comments at @src/shim.rs:
- Around line 1454-1467: Update the short-option cluster handling in
collect_flags so a value guessed after unknown cluster letters is still checked
but cannot set collected.body_given. Preserve the prior body_given value around
read_option when cluster.unknown is nonempty, keeping the existing behavior for
fully recognized clusters.

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ℹ️ Review info

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• Run ID: c8c553c9-7ee5-4f98-9903-2f547fd35374

📥 Commits

Reviewing files that changed from the base of the PR and between 99e23fc and 2ee90c0.

📒 Files selected for processing (6)

• docs/REFERENCE.md
• policy/principles.toml
• src/guard/mod.rs
• src/shim.rs
• src/text.rs
• tests/shim_cli.rs

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