common-room: add Grain as a sibling call-recording source alongside Gong

[adams]

What this changes

Adds Grain (grain.com) as a sibling call-recording source alongside the verbatim Gong reference in partner-built/common-room/.

Files touched

File	Change
partner-built/common-room/.mcp.json	Add grain server block (URL: https://api.grain.com/_/mcp) alongside common-room
partner-built/common-room/skills/call-prep/SKILL.md	Broaden the prioritize-call-recordings line from "Gong and call recording activities" to "Gong, Grain, and other call-recording activities"; add optional clause for direct transcript pull via ~~conversation intelligence MCP
partner-built/common-room/README.md	Mirror the same broadening + transcript-aware note in the Call Prep description

What stays the same

• No changes to account-research, compose-outreach, contact-research, prospect, or weekly-prep-brief
• No changes to either command (/generate-account-plan, /weekly-brief)
• No changes to the Common Room MCP's role as primary signal source — Grain is purely additive for direct transcript access where the activity feed only carries metadata
• Behavior for users who don't connect Grain is unchanged

Why this matters

Common Room's call-prep skill explicitly names Gong in its skill prompt as the prioritized prior-call source. For users who capture meetings in Grain (a meaningful slice of Common Room's SMB/mid-market and community-led GTM customer base) the skill either has no transcript context or surfaces only the activity-feed metadata without the transcript content. Wiring Grain alongside Gong + adding a transcript-pull pathway via the existing ~~conversation intelligence placeholder pattern closes that gap with minimal surface change.

Background on Grain

We're shipping a Grain-published plugin (Cowork partner-built, in design as of late May). Reciprocal opportunity: common-room's call-prep skill already names Gong; Grain is a sibling option that overlaps Common Room's SMB/mid-market segment meaningfully. Grain's MCP launched June 2025 — reference: https://grain.com/release-note/06-18-2025 and https://developers.grain.com.

Anticipated reviewer questions

• Doesn't Common Room's MCP already surface Grain-captured signals via activity history? If a customer captures meetings in Grain and has Grain integrated into Common Room via their existing integration framework, then yes — the metadata is in the activity feed. But the transcript content is not directly accessible to the plugin's skills. The Grain MCP gives the plugin direct transcript and AI-generated-notes access, which is what call-prep actually needs to produce a real prep brief vs. just acknowledging "you had a call with them recently."
• Why broaden the prompt language vs. leave it alone? The verbatim "Gong" reference is a missed opportunity for the plugin's actual user base. Grain users today either ignore the prompt's reference (suboptimal) or the prompt's reference makes the skill quietly worse for them (suboptimal). Broadening to "Gong, Grain, and other call-recording activities" preserves the original semantics for Gong users while letting the skill behave well for Grain users.
• Is this the start of a pattern where every meeting-intel vendor gets a verbatim mention? Not necessarily — Gong is the only one Common Room named explicitly in its skill prompt, so adding Grain alongside it is a small targeted fix rather than the start of a list. If you'd prefer a generic "call-recording / conversation-intelligence sources" rephrasing that drops both vendor names, happy to take that path instead.

cc Common Room maintainers — happy to scope tighter or align with any partner-built convention you'd prefer.

— Mike Adams, Founder/Chairman, Grain