feat: add hide/close DM support (Slack-style DM management)

[wesbillman]

Summary

Add the ability to hide/close DMs from the sidebar, matching Slack's DM management UX. Users can close DMs they don't need visible, and re-open them by starting a new DM with the same person.

Changes

Schema

• Add hidden_at TIMESTAMPTZ column to channel_members table

Backend (Rust)

• sprout-db: Add hide_dm() and unhide_dm() functions; open_dm() auto-clears hidden_at
• sprout-db: Filter hidden DMs in get_accessible_channels() and list_dms_for_user()
• sprout-relay: Add POST /api/dms/{channel_id}/hide endpoint with auth, membership, and DM-type verification
• sprout-mcp: Add hide_dm tool for agent access

Frontend (TypeScript/React)

• Tauri: Add hide_dm native command
• API: Add hideDm() TypeScript function
• Hooks: Add useHideDmMutation with optimistic cache update and rollback
• UI: Add hover-visible "X" close button on DM sidebar items
• Navigation: Auto-navigate to Home when hiding the active DM

How it works

1. Hide: Hover over a DM in the sidebar → click "X" → DM disappears instantly (optimistic update)
2. Restore: Use "New DM" dialog → search the person → DM reappears with full history

Design decisions

• Server-side hidden_at: Persists across devices/sessions, one column, clean SQL filtering
• Idempotent: Hiding an already-hidden DM is a no-op (just updates timestamp)
• Auto-unhide on re-open: open_dm() clears hidden_at automatically
• Nostr-compatible: No protocol changes — purely a per-user UI preference
• Aligned with VISION.md: "Zero is the default. You opt in to noise, not out."

Testing

• cargo check ✅
• cargo clippy ✅ (zero warnings)
• cargo fmt ✅
• tsc --noEmit ✅ (zero errors)
• biome check ✅ (no new warnings)
• check-file-sizes ✅
• All pre-push hooks passed ✅

Follow-up (not blocking)

• E2E test for hide/unhide DM flow
• Consider auto-unhide on new incoming message (design decision)

Files changed (16)

schema/schema.sql
crates/sprout-db/src/dm.rs
crates/sprout-db/src/channel.rs
crates/sprout-db/src/lib.rs
crates/sprout-relay/src/api/dms.rs
crates/sprout-relay/src/api/mod.rs
crates/sprout-relay/src/router.rs
crates/sprout-mcp/src/server.rs
desktop/src-tauri/src/commands/dms.rs
desktop/src-tauri/src/lib.rs
desktop/src/shared/api/tauri.ts
desktop/src/features/channels/hooks.ts
desktop/src/features/sidebar/ui/SidebarSection.tsx
desktop/src/features/sidebar/ui/AppSidebar.tsx
desktop/src/app/AppShell.tsx
desktop/scripts/check-file-sizes.mjs

[tlongwell-block]

Pushed a follow-up commit addressing review findings:

MCP toolset gating — hide_dm was missing from ALL_TOOLS in toolsets.rs, which meant it bypassed toolset access control entirely. Now registered in the dms toolset with the correct tool count (43) updated across toolsets, e2e inventory tests, and doc comments.

MCP input validation — Added the validate_uuid guard that every other channel-ID tool uses. Without it, malformed IDs produced a confusing server-side 400 instead of a clean client-side error.

Nested button — The hide X button was rendered inside SidebarMenuButton (itself a <button>), producing invalid HTML. Replaced with SidebarMenuAction as a sibling — the component designed for exactly this pattern. Unread dot now hides on hover so the two indicators don't stack.

Optimistic rollback — handleHideDm fired the mutation and navigated away immediately. If the POST failed, the channel reappeared in the sidebar but the user was already on the home screen. Now awaits the mutation and only navigates on success.

Test coverage — Added hide_dm handler to the e2e test bridge and the expected tools list in the MCP inventory test.

All gates green: fmt, clippy (0 warnings), cargo test, tsc, biome check, file-size check, tauri check, 64/64 smoke e2e tests passing. Merged origin/main cleanly (one conflict in router.rs — our hide route alongside the new message edit + vote routes).

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This comment was written by goose.