This chapter follows a model turn from input collection to provider request and response handling. It covers what becomes model-visible context, how the request is shaped for a provider, how token pressure is managed, and how failures, retries, quota, and usage are surfaced.
Read this chapter when the question is: what did the model see, why did it see that, and how did the runtime handle the model call?
This page is a chapter guide. Linked implementation pages carry concrete app.js anchors.
| Semantic alias | Minified anchor | Scope |
|---|---|---|
| Context/model loop chapter | N/A — navigation page | Groups prompt/context assembly, attachments, memory, compaction, provider routing, retries, quota, and usage. |
| Context/model implementation pages | See linked source-anchor tables | Concrete bundle anchors live in the destination pages. |
flowchart TD
Input[User input / files / IDE / config] --> Prompt[Prompt and instruction sources]
Prompt --> Attachments[Attachments and file ingestion]
Prompt --> Memory[Memory and context board]
Attachments --> Request[Provider request]
Memory --> Request
Request --> Compaction[Truncation / compaction / checkpoints]
Compaction --> Provider[Provider adapter]
Provider --> Stream[Streaming response]
Provider --> Retry[Retry / rate-limit / fallback]
Stream --> Events[Session events and usage]
Retry --> Request
click Prompt "./prompt-sources/" "Open prompt sources"
click Attachments "./attachments-and-file-ingestion/" "Open attachments"
click Memory "./memory-and-context-board/" "Open memory and context board"
click Compaction "./conversation-compaction/" "Open conversation compaction"
click Provider "./model-api-routing/" "Open model API routing"
click Retry "./resilience-rate-limits-concurrency/" "Open resilience and retries"
| Order | Page | Context/model question answered |
|---|---|---|
| 1 | Prompt sources in Copilot CLI | Which static/runtime prompts, custom instructions, hooks, MCP prompts, and provider mappings feed the request? |
| 2 | Prompt catalog | What prompt families and templates are embedded in the bundle? |
| 3 | Attachment and file-ingestion pipeline | How are images, documents, tagged files, MIME metadata, and size limits mapped into request payloads? |
| 4 | Memory and dynamic context board | How do agentic memory, local memory, context board, rem-agent, sidekicks, and consolidation affect context? |
| 5 | Conversation compaction and memory compression | How do /compact, automatic compaction, request trimming, summaries, and checkpoints manage context pressure? |
| 6 | Model API routing and provider wire formats | How are requests routed to Chat Completions, Responses, WebSocket Responses, or Anthropic Messages APIs? |
| 7 | Rate limits, concurrency, retries, and error recovery | How do retry policy, queue pauses, fallback, cancellation, rate-limit recovery, and request-size handling work? |
| Topic | Page | Why it matters |
|---|---|---|
| Provider identity and auth | Models, providers, and authentication workflows | Explains GitHub auth, BYOK/custom providers, model catalog access, and offline/custom paths. |
| Usage accounting | Usage, quota, and billing metrics | Tracks /usage, assistant.usage, quota snapshots, premium metrics, and token details. |
| Rewind boundaries | Checkpoints, undo, rewind, and fork | Shows how context history can be truncated, replayed, forked, or restored. |
| Agent-specific prompts | Custom agents and skills packaging | Explains AGENTS.md, SKILL.md, custom-agent prompts, allowed-tools, and skill invocation. |
- Context assembly hands model-visible tool schemas to Tools, integrations, and security.
- Durable model/tool events are persisted by Sessions, persistence, and remote.
- Subagent prompt variants and task handoff live in Agents and automation.