Add hosting-plans-helper skill for plan and pricing answers

[gavande1]

Related issues

• Related to STU-1940

How AI was used in this PR

AI assisted with investigating the WordPress.com plans and products APIs, and with drafting the skill, the system-prompt guardrail, and the tests. I reviewed all changes.

Proposed Changes

Studio Code answered WordPress.com plan, pricing, and feature questions from stale training knowledge, so it recommended renamed plans and incorrect feature gating. This adds a hosting-plans-helper skill and a system-prompt rule that requires the agent to answer plan, pricing, and feature questions from current data instead of memory. The skill reads plan names and per-tier features from wpcom/v2/plans/features and prices from wpcom/v2/products, then answers directly without citing the source.

Note: the skill depends on a new wpcom/v2/plans/features endpoint that does not exist yet (separate backend work). Until it ships, the feature fetch returns nothing; the guardrail and price path are already in place.

Testing Instructions

• Checkout 225833-ghe-Automattic/wpcom on sandbox
• Checkout this branch
• npm start
• Open Studio Code, Terminal, Agentic UI
• Ask any question about wordpress.com plans.
• Confirm hosting-plans-helper appears in the Skill tool list.
• After the backend endpoint is live, ask Studio Code a plan question and confirm it answers from fetched data with correct names and localized prices.

CleanShot.2026-06-30.at.18.29.45.mp4

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors? (npm run typecheck passes)

[bcotrim]

Some feedback from testing:

• ✅ Skill is consistently triggered when asking about hosting/plans.
• ⚠️ It still says Personal/Premium can’t install plugins — but plans/features lists install-plugins on Personal and up. So it’s answering from memory and contradicting the fetched data, which is the exact thing the skill is meant to prevent.
• ⚠️ The slug in wpcom/v2/plans/features (premium) doesn’t match the key in wpcom/v2/products (value_bundle) — and there’s no shared field to join on, so the agent can only guess the price mapping (Premium → value_bundle shares no substring, so that one’s especially unreliable). Could we add the product slug to plans/features so consumers can join directly?

[wpmobilebot]

📊 Performance Test Results

Comparing 682fe94 vs trunk

app-size

Metric	trunk	682fe94	Diff	Change
App Size (Mac)	1316.77 MB	1316.77 MB	+0.00 MB	⚪ 0.0%

site-editor

Metric	trunk	682fe94	Diff	Change
load	1062 ms	1114 ms	+52 ms	🔴 4.9%

site-startup

Metric	trunk	682fe94	Diff	Change
siteCreation	6502 ms	6487 ms	15 ms	⚪ 0.0%
siteStartup	1860 ms	6553 ms	+4693 ms	🔴 252.3%

---

Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change (<50ms diff)

[gavande1]

@bcotrim Thanks for testing. I addressed both points. The plan guardrail is now a top-level rule that forbids answering plan questions from memory and calls out the plugins case specifically. For the price join, the backend now returns product_slug and the skill uses it. Do you mind taking another look?