fix: stop Slack hiding pairing chips behind "+N more"

[kylehoehns]

Follow-up to #567, caught in the test env.

The problem

Slack's client renders only the first five buttons of an actions block and collapses the rest into a + N more overflow — regardless of the API's 25-element limit, which is what the original picker was built against.

A day of 8 AM–5 PM is seven chips, so two were hidden. Worse: because every tap rebuilds the block, a chip the teammate had just selected slid straight back under the fold.

Wed, Jul 15
[ 8 AM  ]  [ 9 AM  ]
[ 10 AM ]  [ 11 AM ]
[ 12 PM ]  [ + 2 more ]   ← 1 PM and 2 PM unreachable

The fix

Chunk each day into actions blocks of five, so every time stays visible.

Worst realistic case — seven days of 8 AM–7 PM, 63 chips — is 24 blocks, well inside Slack's 100-block modal cap. A test pins both the five-per-block ceiling and the block-count headroom.

Note on layout

This makes every chip visible and clickable, which was the actual bug. It does not produce a tidy grid: Slack packs buttons two-per-row at modal width, so a nine-chip day renders as 5 (three ragged rows) then 4, with a small seam between the two blocks. Slack gives no column control over buttons.

If the raggedness proves annoying, the alternative is a checkboxes element per day — a clean vertical list, and because checkboxes live in an input block Slack tracks the state natively, which would also eliminate the per-tap round trip, the repaint lag, and the hash conflicts. The cost is that it looks like checkboxes rather than chips. Not doing that here without a call on the trade.

Testing

pnpm verify passes — 265 tests.

🤖 Generated with Claude Code