Update docs for usage-based billing (replace PRU/premium requests model)

[cwebster-99]

Overview

GitHub Copilot is moving from the current PRU (Premium Request Unit) billing model to usage-based billing. We need to update all references to premium requests, model multipliers/model cost, and related billing concepts across the VS Code docs. This includes images where we show model multipliers in the model picker!

Below is an initial scan of where we might need to update - most of this is just updating "request"/"premium request" language.

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Files requiring updates

1. Direct "premium requests" / multiplier references

These pages explicitly discuss premium requests, quotas, overage, and multipliers and will need the most substantive rewrites.

• docs/copilot/customization/language-models.md — heaviest concentration
  • Line 47: "model picker shows the premium request multiplier for premium models" + link to about-premium-requests
  • Line 82: "run out of premium requests, auto will fall back to a model at 0x multiplier"
  • Lines 87–91: "Multiplier discounts" section header + "variable model multiplier" + "request discount" + "see which model and model multiplier"
  • Line 85: weekly usage limits + premium requests remaining note
• docs/copilot/faq.md — quota UI descriptions and agent billing
  • Lines 42–43: "Premium requests" and "Premium requests overage" quota descriptions
  • Line 55: "use all of your premium requests…included models…request additional premium requests" + link to copilot-requests#what-if-i-run-out-of-premium-requests
  • Line 152: "Agents use premium requests from your Copilot plan. Paid plans include a monthly allocation of premium requests…"
• docs/copilot/agents/third-party-agents.md
  • Line 107: "Copilot Pro+ subscription…GitHub Copilot billing and premium requests" + link to copilot-requests
• docs/copilot/agents/agent-tools.md
  • Line 100: "Autopilot uses premium requests in the same way…"
• docs/copilot/customization/hooks.md
  • Line 452: "additional turns consume premium requests" + link to about-premium-requests
• docs/copilot/concepts/language-models.md
  • Line 65: "applies a request discount for paid users"

2. "Monthly limit" / plan structure wording (review and update as needed)

These reference monthly limits and free/paid plan structure. Wording may need updating depending on how usage-based billing changes the plan tiers.

Potential change : "monthly credits"

• docs/copilot/faq.md — lines 19, 26, 34, 40–41, 51
• docs/copilot/overview.md — line 171
• docs/copilot/copilot-coding-agent.md — line 48
• docs/copilot/copilot-cloud-agent.md — line 48
• docs/copilot/getting-started.md — line 27
• docs/getstarted/getting-started.md — lines 34, 175
• docs/supporting/faq.md — line 92
• docs/copilot/setup.md — line 28
• docs/copilot/setup-simplified.md — lines 32, 43
• docs/copilot/ai-powered-suggestions.md — line 28
• docs/copilot/agents/agents-tutorial.md — line 21
• docs/copilot/reference/copilot-vscode-features.md — line 12
• docs/copilot/reference/copilot-settings.md — line 14
• docs/copilot/guides/debug-with-copilot.md — line 18
• docs/copilot/guides/test-with-copilot.md — line 20
• docs/copilot/chat/copilot-chat.md — line 20
• docs/debugtest/testing.md — line 13
• docs/editing/intellisense.md — line 186
• docs/setup/windows.md — line 26
• docs/setup/mac.md — line 26
• docs/setup/linux.md — line 26
• docs/setup/setup-overview.md — line 42

4. Flagging external links to GitHub billing docs

We will need to ensure these links still point to the correct resources.

• https://docs.github.com/en/copilot/concepts/billing/copilot-requests (4 references)
• https://docs.github.com/en/copilot/concepts/billing/copilot-requests#model-multipliers (2 references)
• https://docs.github.com/en/copilot/concepts/billing/copilot-requests#what-if-i-run-out-of-premium-requests (1 reference)
• https://docs.github.com/en/copilot/managing-copilot/monitoring-usage-and-entitlements/about-premium-requests (2 references)
• https://docs.github.com/en/copilot/concepts/billing/individual-plans (1 reference)
• https://docs.github.com/copilot/concepts/usage-limits (7 references)

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