OAuth2 authentication for claude-sdk-cli

[shellicar]

Summary

Replaces the static ANTHROPIC_API_KEY environment variable with a full OAuth2 PKCE flow against the Claude.ai authorisation server.

What changed

Auth flow

• AnthropicAuth class handles the full PKCE flow: build auth URL, open browser, wait for local callback, exchange code for tokens
• getCredentials() is the single entry point — triggers login if no credentials, refreshes if expired
• fetchProfile() called after first login to store subscriptionType and rateLimitTier
• Credentials stored at ~/.claude/.credentials.json
• loadCredentials / saveCredentials validate through authCredentials Zod schema

Token injection

• AnthropicAgentOptions.apiKey: string → authToken: () => Promise<string> (per-request getter, enables transparent refresh)
• TokenRefreshingAnthropic subclasses the Anthropic SDK client and overrides bearerAuth() and apiKeyAuth() — called per-request before validateHeaders
• ApiKeySetter (() => Promise<string>) is declared in the SDK types but the runtime discards non-string values in the constructor (this.apiKey = typeof apiKey === 'string' ? apiKey : null). The subclass fixes this.
• SDK internal types (NullableHeaders, buildHeaders, FinalRequestOptions, etc.) re-implemented in sdkInternals.ts — those paths are not in the package exports map. Linting disabled on that file. Mirrored from @anthropic-ai/sdk@0.82.0.

Build

• Entry point moved from src/main.ts → src/entry/main.ts (matches build entryPoints glob)
• minify tied to !watch, shebang banner added
• dropLabels wired

Notes

• sdkInternals.ts should be verified against SDK source if @anthropic-ai/sdk is upgraded

[bananabot9000]

Clean decomposition. 19 Auth files, each one job. The commit progression tells the story: customFetch injection -> discovered ApiKeySetter is a type lie -> subclass with bearerAuth/apiKeyAuth override -> extract sdkInternals.

Observations:

TokenRefreshingAnthropic - The approach of capturing the getter before super() drops it is solid. The SDK constructor doing typeof apiKey === 'string' ? apiKey : null while declaring ApiKeySetter = () => Promise<string> in the types is exactly the kind of thing that wastes hours. Good that you documented it in the JSDoc.

sdkInternals.ts - The SDK version comment + biome override is the right call. buildHeaders is a faithful mirror including the branded symbol pattern. The upgrade verification checklist in the header comment is good future-proofing.

waitForCallback - server.close() and resolve/reject happen in the same handler. If the browser hits /callback twice (double-click, prefetch), second request hits a closing server. Low risk but noted.

refreshCredentials - parseTokenResponse blanks subscriptionType/rateLimitTier on refresh (empty strings from the token response). Profile data from the original login is lost. getCredentials could carry forward the profile fields from the pre-refresh credentials, or re-fetch profile on refresh.

compactInputTokens - Nice addition. The null trigger when not specified lets the server decide defaults. The 125k->150k bump in the hardcoded call site matches the compaction threshold bump in the commit message.

pnpm override @anthropic-ai/sdk@>=0.79.0 <0.81.0: >=0.81.0 - Agent SDK 0.2.92 was pulling 0.74.0 as a dep? The override forces it to 0.82.0 which is what your sdkInternals mirrors. Smart.

execFile('open', ...) - macOS only. Fine for now since that's the target, just noting it for when linux/WSL becomes relevant.

Build changes (splitting, dropLabels, shebang, minify tied to !watch) are consistent across both cli and sdk-cli. Good hygiene.

LGTM.