ticket-create skill — centralize issue creation discipline outside tool descriptions

Context

Issue-creation logic currently lives across four disjoint surfaces:

1. create_issue MCP tool description — mandates a visible proposal + labeling rules
2. .agent/skills/ticket-intake/ — covers consumption of EXISTING tickets (validation sweep, ROI, branch-before-code), not creation
3. AGENTS_STARTUP.md §9 "Fat Ticket Protocol" — body-level structure (Problem / Architectural Reality / Gold Standards / Traps)
4. Tribal knowledge — anti-patterns that have no canonical home (e.g., [enhancement] prefixes in titles duplicating label taxonomy, Origin Session ID placement, duplicate sweep via grep_search on local issue dirs, rename-in-parens scope guidance)

The fragmentation means every new session re-derives the discipline from tool descriptions + precedent-following, which perpetuates existing anti-patterns. A dedicated skill would:

• Give agents a single view_file target at creation time
• Centralize the anti-pattern list so fixing one place fixes all future tickets
• Mirror the ticket-intake skill's separation of concerns (intake = consume existing; create = produce new)

The Fix

Create .agent/skills/ticket-create/ with:

1. SKILL.md — trigger description; invoked before create_issue is called.
2. references/ticket-create-workflow.md — the canonical workflow:
   • Pre-creation duplicate sweep (grep_search resources/content/issues/)
   • Five-stage challenge chain applied at creation time (not just intake): premise → prescription → substrate → consumer → service-boundary
   • Title hygiene: NO prefix in title duplicating label taxonomy ([enhancement] / [bug] / [epic] belong to labels, not titles); title should describe the subject, not the category
   • Label rules: ai mandatory; one primary (epic/enhancement/bug); secondary labels (architecture, documentation, etc.) as applicable
   • Fat Ticket body structure: Context, The Problem, The Fix, ACs, Out of Scope, Related, Origin Session ID
   • Visible proposal protocol (reinforce the MCP tool description's MANDATORY step)
   • Linkage rules: parent issue for epics, blocking / blockedBy for dependencies, Origin Session ID for A2A context
3. assets/ticket-proposal-template.md — the visible-proposal format agents dump into chat before calling create_issue

Acceptance Criteria

• .agent/skills/ticket-create/SKILL.md exists with proper frontmatter trigger
• references/ticket-create-workflow.md codifies the full workflow + anti-pattern list
• assets/ticket-proposal-template.md provides the visible-proposal format
• AGENTS_STARTUP.md §9 updated to reference the new skill (replace inline Fat Ticket protocol with a pointer)
• create_issue MCP tool description updated to reference the skill as the canonical entry point
• A representative test: generate a new test ticket through the skill, verify it hits all the hygiene rules (no [] prefix in title, labels correct, body structure, Origin Session ID present)

Anti-Patterns to Codify (non-exhaustive)

• Title prefix duplicating labels: [enhancement] X when enhancement is already a label
• Skeleton tickets: one-sentence bodies without architectural context (AGENTS_STARTUP.md §9.4 already forbids but needs enforcement mechanism)
• Missing Origin Session ID: breaks A2A Contextual Bridge (§14)
• Missing duplicate sweep: grep_search on resources/content/issues/ + resources/content/issue-archive/ + resources/content/discussions/
• Stale precedent-following: filing without applying the five-stage challenge chain
• Cross-scope bundling: [Epic] titles for single-commit tickets (§9.2 forbids but no tooling check)

Out of Scope

• Migrating existing tickets' title prefixes (would require mass rename; separate doc ticket if worth it)
• ticket-intake skill changes — that skill consumes existing tickets; creation is its dual

Related

• Sibling: .agent/skills/ticket-intake/ — consumption dual
• AGENTS_STARTUP.md §9 — current scattered location for Fat Ticket body rules
• create_issue MCP tool — current scattered location for label rules + visible proposal
• Session memories observing the fragmentation: this session's multiple ticket creations (#10103, earlier #10085/#10086/#10087 inheritances)

Origin Session ID: 1db25bbe-f39d-4dcd-bb0e-bc125ce91326