Sierra (Bret Taylor) Series C — what closed in April 2026
Sierra raised a Series C at a reported $4.5B valuation on April 21, 2026, led by Greenoaks with Sequoia and Benchmark following — a 3x markup in eight months.
6 min read
Guides & News
Guides & News archive page 16 of 68
AI Guides, Tutorials & News
Step-by-step guides, technical tutorials, and use-case playbooks for building AI voice and chat agents — plus the latest AI news, model releases, funding, and policy developments.
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Hierarchical Agent Handoffs (OpenAI Agents SDK) vs Vapi Squads
Triage to specialist to return-to-orchestrator pattern explained with code. CallSphere's OpenAI Agents SDK handoffs vs Vapi Squads' linear chain.
9 min read
Spam + Robocall Mitigation: CallSphere vs Vapi Reputation Systems
STIR/SHAKEN, branded calling, opt-in lists, carrier reputation. How CallSphere builds outbound trust vs Vapi defaults. Real-world spam-flag remediation.
15 min read
Llama 4 Licensing: What Commercial Use Looks Like in 2026
Meta updated the Llama license for Llama 4 — here is what changed, who can deploy commercially, and the 700M-MAU clause. Lens: healthcare. A 2026 builder briefing.
6 min read
Google Antigravity IDE: Multi-Agent Coding Goes Mainstream
Google launched Antigravity, a multi-agent IDE that orchestrates coding, testing, and review agents — what it is and why it matters. Practical context for teams in Massachusetts.
6 min read
Grok 4 on X: Real-Time AI Across the Platform — Nashville Builders...
Grok 4 is now woven across X (formerly Twitter) — search, replies, summaries, and live event coverage. Practical context for teams in Nashville, TN.
6 min read
Codestral 25.05 Fill-in-the-Middle: The IDE Integration Story
Codestral 25.05 ships with state-of-the-art FIM performance — here's why that matters for IDE integration. Practical context for teams in Texas.
9 min read
AI model cards and disclosure rules in 2026 — what regulators now
By April 2026 EU AI Act, NIST AI RMF 2.0, and US procurement rules all converge on a model-card-style disclosure baseline — but the exact fields still differ across regimes.
6 min read
Anthropic Series F speculation — what April 2026 suggests
Reporting in April 2026 from The Information and Bloomberg suggests Anthropic is in early talks for a Series F at a $200B+ valuation, anchored by a major sovereign LP.
6 min read