feat: BYOK onboarding, provider commands, docs, and polish

[ChrisRomp]

Summary

PR 3 of 3 in the BYOK provider series. Adds user-facing onboarding commands, documentation, error handling, and polish discovered during live testing.

What it does

• /provider command with list, test, and add/remove subcommands
• BYOK-aware error messages (connection refused, auth failure, model not found)
• Provider connectivity testing (/provider test <name>)
• Model-level wireApi override (mix completions and responses models on one provider)
• providers topic in fetch_copilot_bridge_documentation tool (admin/non-admin variants)
• Admin agent can manage provider config directly (/provider add detects admin role)
• Fixed current" indicator when BYOK model shares name with Copilot modeldouble "
• Fixed same-provider model switch creating new session when wireApi differs
• Full BYOK documentation in docs/byok.md

Key changes

• src/core/command-handler.ts: /provider commands, admin-aware add/remove, isCurrent fix
• src/core/session-manager.ts: BYOK error wrapping, wireApi change detection in switchModel
• src/index.ts: testProviderConnectivity(), provider_test action handler
• src/config.ts: Model-level wireApi validation and resolution
• src/core/bridge-docs.ts: New providers topic with full BYOK docs
• docs/byok.md: Comprehensive BYOK guide
• 559 total tests (18 new)

Known limitations (follow-up)

• /provider test uses simplified connectivity check, not full SDK resolution path
• Removing a provider while channels reference it logs a warning but doesn't auto-reset prefs

Prior PRs

• [feat: BYOK provider config and plumbing #131](https://github.com/ChrisRomp/copilot-bridge/pull/ Config + plumbing131)
• [feat: BYOK model provider-aware resolution and switching #132](https://github.com/ChrisRomp/copilot-bridge/pull/ Model UX132)

[Copilot]

Pull request overview

Completes the BYOK provider feature series by adding user-facing /provider onboarding commands, richer BYOK documentation surfaced via bridge docs, model-level wireApi overrides, and improved session behavior/error messaging when working with external providers.

Changes:

• Added /provider command (list + test) and admin-aware guidance for adding/removing providers.
• Implemented model-level wireApi overrides (config validation + provider resolution) and session recreation when wireApi changes within the same provider.
• Added BYOK documentation (docs/byok.md) and a new providers topic in fetch_copilot_bridge_documentation, plus supporting README/agent docs updates.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
templates/admin/AGENTS.md	Admin runbook updates for BYOK provider management
src/types.ts	Adds model-level wireApi to provider model entries
src/index.ts	Adds provider connectivity test helper + provider_test action handling
src/core/session-manager.ts	Applies model-level wireApi during session (re)create; recreates session on same-provider wireApi change; improves BYOK error messaging; adds docs topic enum
src/core/command-handler.ts	Implements /provider(s) command UX + help updates; fixes “current model” indicator for BYOK models
src/core/byok-providers.test.ts	Adds tests for model-level wireApi validation + resolution
src/core/byok-onboarding.test.ts	New tests covering /provider UX behaviors
src/core/bridge-docs.ts	Adds providers documentation topic with admin/non-admin variants
src/core/bridge-docs.test.ts	Extends docs tests to cover new topic
src/config.ts	Validates model-level wireApi; resolves provider config with per-model override
docs/byok.md	New comprehensive BYOK guide
config.sample.json	Updates sample BYOK config to demonstrate per-model wireApi
README.md	Adds BYOK to feature list + links to BYOK docs
AGENTS.md	Updates internal agent guidance to include BYOK behaviors and commands

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[Copilot]

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

src/index.ts:843

• testProviderConnectivity() always sends Authorization: Bearer ... regardless of provider type. Azure OpenAI expects api-key, and Anthropic expects x-api-key (plus required version headers), so /provider test will give false negatives even when the provider config is correct. Suggest setting auth headers based on provider.type (reusing the same logic as the SDK/provider resolution where possible).

  const headers: Record<string, string> = { 'Accept': 'application/json' };
  if (apiKey) headers['Authorization'] = `Bearer ${apiKey}`;
  else if (bearerToken) headers['Authorization'] = `Bearer ${bearerToken}`;

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