refactor: consolidate provider architecture and shared search logic

[emilsvennesson]

Summary

• Reorganize providers into folder-based modules (anthropic/, openai/, copilot/) and add shared provider utilities for OpenAI-compatible client/response handling and error formatting.
• Centralize provider detection/metadata in a registry and replace branching dispatch in src/index.ts with a provider adapter map.
• Refactor config/provider resolution to reuse shared scanning logic, split constants by ownership (provider-local vs shared), and remove the old global src/constants.ts.
• Shift import sorting responsibility to Oxfmt by adding .oxfmtrc.json and disabling sort-imports in Oxlint.

Validation

• bun run format
• bun run check
• bun run build

[Copilot]

Pull request overview

This PR refactors the provider implementation to a folder-based architecture (Anthropic/OpenAI/Copilot), introduces shared utilities for OpenAI-compatible providers, and centralizes provider detection/metadata so the plugin entry point can dispatch via a provider adapter map instead of branching logic.

Changes:

• Consolidates shared search request/response helpers and OpenAI-compatible response parsing into src/providers/shared/*.
• Introduces src/providers/registry.ts (provider rules + detection) and src/providers/index.ts (adapter-based dispatch), and rewires src/index.ts to use them.
• Refactors provider scanning/resolution in src/config.ts and removes the legacy global src/constants.ts; updates formatting tooling to let Oxfmt own import sorting.

Reviewed changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/providers/shared/search.ts	Adds shared search constants + helpers (input building, structured response).
src/providers/shared/openai-compatible.ts	Adds shared OpenAI/Copilot client creation and response text/hit extraction utilities.
src/providers/shared/errors.ts	Adds shared fallback error formatting for providers.
src/providers/registry.ts	Centralizes provider metadata and detection (npm package + provider ID hints).
src/providers/openai/index.ts	Rehomes OpenAI provider implementation to folder module using shared helpers.
src/providers/openai.ts	Removes legacy OpenAI provider implementation file.
src/providers/index.ts	Adds provider adapter map for unified dispatch + error formatting.
src/providers/copilot/index.ts	Rehomes Copilot provider implementation to folder module using shared helpers.
src/providers/copilot/constants.ts	Adds Copilot-specific constants scoped to Copilot provider module.
src/providers/copilot/auth.ts	Updates Copilot auth helper to import provider-local constants.
src/providers/copilot.ts	Removes legacy Copilot provider implementation file.
src/providers/anthropic/index.ts	Updates Anthropic provider to use shared search helpers and shared error formatting.
src/providers/shared/errors.ts	Introduces shared error helper used across providers.
src/index.ts	Replaces branching provider dispatch/detection with registry + adapter dispatch; keeps model resolution logic but simplifies priority handling.
src/constants.ts	Removes legacy global constants module (constants now owned by shared/provider modules).
src/config.ts	Refactors provider scanning/resolution to reuse shared detection + scanning helpers and to support new registry approach.
AGENTS.md	Updates repo structure documentation to match the new provider module layout.
.oxlintrc.json	Disables sort-imports in oxlint (import sorting delegated to formatter).
.oxfmtrc.json	Adds Oxfmt import grouping config for consistent import ordering.

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