[backport] Fix issue_write MCP App form gating for labels/assignees/milestone/type (upstream main)

[gastrodon]

Summary

issue_write's form-gating logic uses issueWriteFormParams to decide whether to show the MCP App form or execute directly: a call with any parameter outside the allowlist bypasses the form. The form pre-fills and re-submits labels, assignees, milestone, and type, but those four were absent from the allowlist — so any call passing them skipped the confirmation UI.

Fix: add labels, assignees, milestone, and type to issueWriteFormParams. The allowlist now covers every property in the current input schema, leaving issueWriteHasNonFormParams as a forward-compatibility safety net for future properties added without form support.

Also corrects inaccurate tool description text on issue_write and create_pull_request that claimed the form did not collect fields it actually does.

Upstream reference

• version: upstream main (post v1.4.0, unreleased)
• commits: github@3c4749d
• PR: Show issue_write MCP App form for labels/assignees/milestone/type github/github-mcp-server#2767

Fork conflict

None. The fork does not use MCP Apps UI for its custom tools.

Context

Agents calling issue_write with label or assignee changes were bypassing the confirmation form silently, undermining the user-confirmation guarantee that MCP Apps is designed to provide.

[gastrodon]

Unified Changelog — upstream main since v1.4.0

See #10 for the full changelog. Summary:

• [backport] OAuth 2.1 stdio login (upstream main) [story] #13 (story): OAuth 2.1 stdio login → sub-issues [backport] OAuth 2.1 core library — PKCE + device flows (upstream main) #10 [backport] Wire OAuth 2.1 login into stdio server (upstream main) #11 [backport] OAuth build-time credentials + docs (upstream main) #12
• [backport] Issue dependency read/write tools (upstream main) #14: Issue dependency read/write tools
• [backport] get_parent method for issue_read (upstream main) #15: get_parent for issue_read
• [backport] Promote issue fields to default, remove legacy issue_write methods (upstream main) #16: Promote issue fields, remove legacy issue_write
• [backport] Remove show_ui parameter, centralize show/defer decision (upstream main) #17: Remove show_ui, centralize show/defer
• [backport] Fix delete:true on issue fields — REST DELETE fallback (upstream main) #18: Fix delete:true on issue fields
• [backport] Bound ui_get pagination to prevent latency spikes (upstream main) #19: Bound ui_get pagination
• [backport] Fix issue_write MCP App form gating for labels/assignees/milestone/type (upstream main) #20: Fix issue_write form gating
• [backport] Validate required params in add_comment_to_pending_review (upstream main) #21: Validate required params in add_comment_to_pending_review

[gastrodon]

No-op. The fork's issueWriteFormParams (in pkg/github/issues.go line 1734+) already includes labels, assignees, milestone, and type. Confirmed at lines 1742–1745. No work needed.