MAS Studio AI assistant, product catalog, release-flow enhancements, and the mas-ost monorepo workspace integration.

Resolves https://jira.corp.adobe.com/browse/MWPW-183572
QA Checklist: https://wiki.corp.adobe.com/display/adobedotcom/M@S+Engineering+QA+Use+Cases

What is in this PR

Two commits, both tagged with the Jira ticket:

1. MWPW-183572: AI chat assistant, product catalog, release flow + IO Runtime — the full feature delivery plus the pre-review audit fixes baked in.
2. MWPW-183572: integrate mas-ost as a monorepo workspace — OST source relocated from tacocat.js/mas-ost into this repo as the 4th npm workspace. Distinct architectural change, separate commit so reviewers can isolate the build/workspace question.

Feature commit contents

Studio frontend

• Conversational AI chat (mas-chat.js + friends): Bedrock-backed, persistent sessions via chat-session-manager, operation preview + confirmation gating, destructive-tool allowlist enforced on the client.
• Product catalog (mas-product-catalog.js / mas-product-detail.js): multi-select filters, surface-scoped editor/settings access (groups.js introduces isMasAdmin, canAccessSettings, getUserSurfaces), DRAFT landscape toggle, applied-filter chips.
• MCS-integrated release flow: deterministic fragment content sourced from MCS merchandising data, dual-OSI plumbing for plans variants, multi-select OST hookup in rte/ost.js.
• services/mcp-client.js: defensive guards on MCP response shapes (publish/get/copy/update contract drifts), AbortController on the AI chat fetch, URL-scrubbed logError helper applied across 14 call sites.
• utils/ai-card-mapper.js: XSS-safe badge HTML via escape helpers; preserves explicit falsy field values (0, '', false); trim-aware title fallback chain.
• utils/mas-chat-helpers.js: pure helpers extracted for direct unit testing.
• markdown-parser.js: LRU-bounded cache to short-circuit repeat renders.

IO Runtime — AI chat backend (io/studio/src/ai-chat/)

• AWS Bedrock integration with prompt-injection defense via wrapUntrusted sentinel envelopes. Attached-card fragment IDs wrapped element-wise instead of raw JSON.stringify to close a breakout vector.
• Modules: bedrock-client, operations-handler, operations-prompt, prompt-templates, response-parser, variant-configs, variant-knowledge-builder, knowledge-client, validation, index.js.

IO Runtime — MCP server (io/mcp-server/)

• 31 runtime actions covering card + collection + offer + product CRUD/search.
• Surface-scoped authz on fragment-creating actions (create-release-cards, create-card, create-collection, copy-card) via new helpers in lib/ims-validator.js — deriveSurfaceFromPath, fetchUserGroups, canEditSurface, requireSurfaceAccess. Prevents cross-surface mutation via direct API calls.

mas-mcp-server (stdio entry for Claude Code / Cursor)

• Retired the Express HTTP bridge (http-server.js). Dropped cors / express deps + the http npm script.

Web components

• Small audit touches on aem-fragment, merch-card-collection, Express pricing variants.

mas-ost workspace commit

• 63-file source tree extracted from tacocat.js/mas-ost@f5a71b9: Lit 3 + Spectrum Web Components, Vite build, WTR tests.
• Registered in root package.json workspaces. Build script outputs the IIFE bundle and copies to ../studio/ost/index.js in one step.
• Byte-for-byte identical bundle output validated via in-browser smoke test (window.ost.openOfferSelectorTool exposed, all 5 custom elements registered, no JS errors at load).

Testing

• Full studio suite: 1240 pass / 0 fail / 2 skipped (same as baseline on main).
• 10 new characterization tests in studio/test/** covering every new service/util + 2 XSS + 1 prompt-injection repro.
• 2 new tests in io/studio/test/ai-chat/ (bedrock-client, operations-handler).
• 1 new file in io/mcp-server/test/lib/ with 23 tests: canEditSurface matrix, fetchUserGroups edge cases, full requireSurfaceAccess middleware integration.
• mas-ost suite: 209 pass / 4 pre-existing upstream failures (3 country-picker SWC lifecycle + 1 OstStore.addOffer.tryBuy). Not regressions from the integration. Tracked as follow-up.

Please do the steps below before submitting your PR for a code review or QA

• C1. Cover code with Unit Tests — 20+ new characterization tests; 1240 studio tests green.
• C2. Add a Nala test (double check with #fishbags if nala test is needed).
• C3. Verify all Checks are green (unit tests, nala tests) — studio suite green locally; CI will confirm.
• C4. PR description contains working Test Page link where the feature can be tested.
• C5: you are ready to do a demo from Test Page in PR.
• C.6 read your Jira one more time to validate that you have addressed all AC and nothing is missing.

Follow-up (filed as deferred, not PR-blocking)

• Per-fragment surface authz on id-based MCP mutations (update-card, delete-card, publish-card, bulk-*). This PR gates path-based creation; id-based mutations currently rely on AEM's own ACLs to scope access.
• Dev-namespace 14257-merchatscale-axel remains hardcoded in studio/src/constants.js, studio/src/services/product-api.js, and io/studio/src/ai-chat/knowledge-client.js with a TODO pointing at the post-merge swap to masstudio once that deploy completes.
• 4 pre-existing mas-ost tests inherited from upstream (country-picker SWC + OstStore tryBuy) need fixing.
• io/knowledge (the AI knowledge service / RAG backend) was intentionally scoped out of this PR. It's a separate Runtime app with its own lifecycle; RAG_ENABLED=false keeps the chat fully functional without it.

Test URLs:

• Before: https://main--mas--adobecom.aem.live/
• After: https://mwpw-183572--mas--adobecom.aem.live/

Screenshots

To be added: OST dialog opened from AI chat, product catalog with multi-select filters, AI chat confirmation summary, release card preview.