Apex (Fable 5)

Apex is what you reach for when the task is genuinely hard. The model underneath is Claude Opus 4 / Fable 5 — Anthropic's top tier, costlier and slower than Sonnet, but with reasoning quality nothing else matches. Most of what you ask me for, Sonnet handles cleanly. Apex is for the rest.

When to actually use Apex

• Deep research — synthesizing fifteen sources into a clean argument with the trade-offs called out. Sonnet writes it; Apex holds it.
• Complex planning — long horizon, many constraints, real trade-offs you'd otherwise need a Saturday to think through.
• Subtle reasoning — legal-adjacent work, financial analysis, contract redlines, edge cases where Sonnet sometimes misses nuance.
• High-stakes drafting — investor letters, board memos, strategic docs, the email you only get one shot at.

For daily email triage, scheduling, summaries, status pulls — Sonnet handles cleanly at a fraction of the cost. Apex is the wrong tool for those; you'll wait longer and pay more for an answer that wouldn't have been better anyway.

How it works

Apex is enabled per conversation. From the chat surface, toggle "Apex mode" before sending the first message. Niyra routes that thread through Claude Opus 4 via your BYOK Anthropic key. Cost runs on your vendor account, not your Niyra credits.

There's no failover. Apex doesn't downgrade to Sonnet mid-conversation — that would silently change the quality of work already in flight. If you run out of vendor quota, the conversation pauses until you top up. I tell you when that happens, in plain English, before anything important breaks.

BYOK requirement

Apex is BYOK-only. I don't include Opus pricing in credits because the math doesn't work for most users — you'd be paying for headroom you rarely use. Bringing your own key means:

• You see exact vendor charges in your Anthropic console.
• You can set your own monthly cap.
• You can pause Apex by removing the key without affecting the rest of Niyra.

See BYOK setup to plug your Anthropic key. Two minutes, one form, encrypted at rest.

A real run

You:  (Apex on) Read these three CVC term sheets and tell me what
      the founder gives up most in each, in plain English.

Me:   Working through them. Quick read first, deep pass next.

      First pass — the headline:
        • Sheet A: 2× participating preference, 4-year vesting.
        • Sheet B: 1× non-participating, but board control flip
          at >$10M ARR loss.
        • Sheet C: 1× non-participating, full ratchet anti-dilution.

      Deep pass on what you actually lose:
        Sheet A is the worst on exit math. Participating
        preference means they get their 2× back AND their pro-rata
        share — at $20M exit, that's $4M off the top before the
        common pool even sees money.
        Sheet B looks fine until the board flip kicks in. If you
        miss the $10M trigger, you lose veto on hiring/firing the
        CEO. That's the live bullet here.
        Sheet C is cleanest on paper. Full ratchet bites only if
        you raise a down round — which, given your traction, is
        the lowest-probability scenario of the three.

      My ranking by what-you-lose-most: A > B > C.
      Want me to draft the redline counters for any of them?

That kind of read — actually holding the docs in mind, weighing the trade-offs, reasoning about the reasoning — is where Apex earns its cost.

Alpha access

Apex is gated to early Alpha users today. We're learning what tasks people actually run on it before opening it broadly. The one-line use case is the filter: if you have a specific high-stakes job you want Opus on, you're in.

Email hi@niyra.ai with that one line.

Pairs well with

• BYOK — required, not optional.
• Memory — Apex reasons better when it has your context; memory provides it.
• Research briefs use case — the canonical Apex workflow.