[mykytanetipa]

An owner-only file hides tokens from other users on the machine, not from other programs running as you, backups, or synced dotfiles. This adds an optional keychain store mode that keeps access and refresh tokens in macOS Keychain, Windows Credential Manager, or Linux Secret Service. Plain file storage remains the default.

Example:

$ a2a send -a https://agent.example.com --oauth-store keychain "hello"
To authorize, open:
https://auth.example.com/authorize?client_id=my-cli-client&...
Authorized. Grant saved for https://agent.example.com.
[agent] Hi!

$ cat ~/.config/a2a-cli/oauth/keychain-grants.json
{
  "version": 1,
  "grants": [
    {
      "key": {
        "issuer": "https://auth.example.com",
        "client_id": "my-cli-client",
        "resource": "https://agent.example.com",
        "scopes": ["a2a.invoke"]
      },
      "token_type": "Bearer",
      "expires_at": "2026-11-03T22:57:51.27214951Z",
      "endpoints": {
        "issuer": "https://auth.example.com",
        "authorization": "https://auth.example.com/authorize",
        "token": "https://auth.example.com/token",
        "revocation": "https://auth.example.com/revoke"
      },
      "created_at": "2026-11-03T21:57:51.27214951Z",
      "client_source": "config"
    }
  ]
}

$ a2a auth get https://agent.example.com --oauth-store keychain --reveal
oauth grants:
RESOURCE                   ISSUER                    CLIENT         SCOPES      EXPIRES
https://agent.example.com  https://auth.example.com  my-cli-client  a2a.invoke  2026-11-03T22:57:51Z (refreshable)
access token for https://agent.example.com: at_0422e9fa19c466f2d56d16e4

Cross-platform keychains accessed through go-keyring only look up entries by key and cannot enumerate stored grants on their own. To support listing and matching grants cleanly, the keychain store keeps non-secret metadata in its own index file, keychain-grants.json, so the file store never mistakes a keychain grant for one without tokens. That metadata covers issuer, client, agent URL, scopes, expiry, and endpoints, while the access and refresh tokens live in the OS keychain as separate entries, which keeps each within the size limits of the macOS and Windows stores.

Saving a grant writes to the keychain before touching the index file on disk. When no keychain service is running, such as on a headless Linux session without Secret Service, or a token is too large for it, the write fails immediately with a message saying which. Rather than quietly falling back to writing tokens to disk, it points the user to the file store.

Fixes #98

[yarolegovich]

List reads both tokens of every grant from the keychain, but callers only compare keys and then Get the one they picked. let's return index metadata from List and read secrets only in Get

[mykytanetipa]

Fixed in mykytanetipa#7. List reads only the index, which also records whether a grant is refreshable, and secrets are read only in Get. The SDK's Store contract allows List to leave tokens out (a2aproject/a2a-go#569).

[mykytanetipa]

Closing in favor of the a2a-go OAuth client (a2aproject/a2a-go#568, a2aproject/a2a-go#569, a2aproject/a2a-go#570) and the CLI changes built on it (mykytanetipa#6, mykytanetipa#7).