Problem

DeepSeek extended the V4 Pro 75% promotional discount from 2026-05-05 to 2026-05-31 15:59 UTC (verified directly from https://api-docs.deepseek.com/quick_start/pricing — the docs explicitly say "The deepseek-v4-pro model is currently offered at a 75% discount, extended until 2026/05/31 15:59 UTC.")

Our pricing.rs still hard-codes the old May 5 date, so once today rolls past that timestamp every cost estimate the TUI shows for V4 Pro will be 4× higher than what users will actually be billed. Cost telemetry will misread, hourly cost projections will scare people off Pro for the rest of May, and the in-TUI footer / /cost view will be confidently wrong.

Concrete change

crates/tui/src/pricing.rs:18-22

fn v4_pro_discount_ends_at() -> DateTime<Utc> {
    Utc.with_ymd_and_hms(2026, 5, 5, 15, 59, 0)   // ← change to 5, 31
        .single()
        .expect("valid DeepSeek V4 Pro discount end timestamp")
}

Also update the comment in the discount branch (pricing.rs:40) from 2026-05-05 to 2026-05-31.

If a pricing_for_model_at test pins on the May 5 date, update that too. Run:

cargo test -p deepseek-tui --bin deepseek-tui --locked pricing

Acceptance criteria

• Constant + comment updated to 2026-05-31 15:59 UTC
• Pricing tests pass
• CHANGELOG entry under v0.8.4 noting the schedule change (link to DeepSeek docs)

Why this should ship soon, not wait

Real-world clock is already very close to 2026-05-05. Any release that ships after that date with the old constant will start showing 4× cost numbers. Worth a fast-follow patch even if v0.8.4 is further out — could land as v0.8.3.1 / hotfix.

Source

https://api-docs.deepseek.com/quick_start/pricing — the discount banner explicitly states "extended until 2026/05/31 15:59 UTC". Verified at the time of filing.