[johnnyelwailer]

Problem

show_widget-produced widgets rendered with a hard-coded dark palette regardless of the host theme — and stayed frozen on the mount-time palette after any light/dark flip.

Two independent defects:

1. The model never saw the widget authoring contract. The theme-token + icon-sprite contract (use var(--*) host theme variables for every color, use the t3w-icon sprite, never ship a palette) was codified in packages/project-context as T3TEAM_WIDGET_AUTHORING_GUIDANCE with a doc that explicitly names "the MCP tool's widget_code input schema" as a carrying surface — but the live Tool.make("t3team_show_widget", ...) wrapper had shipped with a bare description and widget_code: Schema.String since the MCP toolkit was carved out of the catalog on 2026-07-19 (03953ee "expose inline widgets to provider agents"). The Aug 29 guidance-constant work wired the contract into the catalog snapshot and the help topic, and tests locked the catalog — but the live schema was never wired, and no test locked the live surface.

2. The host theme snapshot was taken once, at mount. The widget srcdoc cannot inherit host CSS custom properties, so the theme is snapshotted into the iframe's own :root at build time — but the srcdoc memo depended only on [widget.html, nonce], so after a light/dark flip (user toggle, or OS change under system-follow) the widget stayed on the old palette while the host re-themed around it.

Changes

Fix 1 — live schema carries the contract (62c49e3)

• T3TEAM_WIDGET_SHOW_TOOL_DESCRIPTION added to t3teamWidgetGuidance.ts as a second shared constant (single source of truth; the "two surfaces must not restate" invariant is preserved — the guidance doc now enumerates the constants instead of restating the text).
• apps/server/.../t3team/tools.ts: live tool description + title/widget_code property annotations now use the shared constants via Schema.annotate({ description }) (the established Effect-4 pattern in this file).
• t3team-mcpToolInputSchema.test.ts: three new assertions lock the live JSON schema (not just the catalog snapshot) to the documented contract — the class of drift that produced this bug is now a red build.

Fix 2 — re-snapshot on theme flips (4d06e84)

• New useThemeSnapshot() export in apps/web/src/hooks/useTheme.ts: the raw ThemeSnapshot with referential stability (invalidated only when the resolved theme actually changes). useTheme() allocates a fresh object per render and would defeat the memo — the new test caught exactly that.
• t3team-useWidgetBlockController.ts: the srcdoc memo now depends on the stable snapshot → widgets rebuild exactly on real theme flips, zero rebuilds on plain re-renders.
• New t3team-widgetBlockThemeResync.test.tsx: mount-snapshot, exactly-one-rebuild on light→dark flip (verified in the live iframe DOM), no rebuild on plain re-render.

Verification

• packages/project-context: typecheck + guidance/catalog tests green.
• apps/server: 25/25 MCP tool input-schema tests (incl. the 3 new live-schema locks), 25/25 t3team toolkit + widget-show tests green.
• apps/web: web typecheck green; 3/3 new resync tests; 22/22 pre-existing widget-suite tests green.
• End-to-end on a fixed instance (standalone src/t3team-bin.ts serve from this branch, scratch project, Nexplore provider): two fresh threads asked to visualize things with zero design hints (no mention of themes, colors, tokens, icons, or layout). Both agents' t3team_show_widget calls (4 total, verified in provider event logs) produced contract-clean widgets: HTML fragment (no <!DOCTYPE>), zero hard-coded hex colors, 12 host theme tokens each, t3w-icon sprite, no emoji glyphs — and neither agent called the help topic, so the contract reached them purely through the live tool schema. Pre-fix control: this conversation's own orchestrator widget hard-coded 8+ hex values with the old schema.

Notes

• Greenfield-style: no compatibility fallbacks; the catalog entry now points at the same constant instead of a duplicated string.
• The pre-existing widget-guidance help topic is unchanged — it remains the on-demand deep reference.