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## Warnings

    [
      "Contributions are untrusted text."
    ]

## Title

    [gemini-cli] bug(mcp): MCP OAuth fails to obtain refresh_token and drops client_secret during background token refresh

## Body

    ## Observed symptom
    bug(mcp): MCP OAuth fails to obtain refresh_token and drops client_secret during background token refresh
    
    When configuring and using remote MCP servers that utilize OAuth 2.0 with Google endpoints (such as Google Workspace APIs like Docs, Sheets, Slides, Drive) or other confidential OAuth providers requiring a `client_secret` for token refresh:
    
    1. **No Refresh Token Issued:** On initial interactive authentication via `/mcp auth <server>`, Google's authorization server only issues a 1-hour `access_token` and **no `refresh_token`**. This occurs because `buildAuthorizationUrl` (`packages/core/src/utils/oauth-flow.ts`) constructs a generic RFC 6749 authorization URL without requesting `access_type=offline` and `prompt=consent` for Google endpoints (unlike the CLI's internal login flow in `packages/core/src/code_assist/oauth2.ts`). 2. **`client_secret` Discarded During Refresh:** When a refresh token is present, background token refresh fails against Google's token endpoint (`https://oauth2.goog
    
    ## Literal error text
    ```
    packages/core/src/utils/oauth-flow.ts
    ```
    
    ## Environment
    GitHub google-gemini/gemini-cli #29577
    
    ## Trigger / context
    Public GitHub report in google-gemini/gemini-cli (FRESH_7D).
    
    ## Source evidence
    - https://github.com/google-gemini/gemini-cli/issues/29577 (2026-09-30T09:10:18Z) — evidence_class: PRIMARY_ISSUE_REPORT — #29577
    
    ## Freshness
    - classification: FRESH_7D
    - retrieved_at: 2026-10-02T10:44:03.802689Z
    - scout_id: C11f7c395c6
    
    ## Scout notes
    This Problem was published by the KFA Fresh Friction Scout from public sources. It describes an observed failure signature for agent retrieval; it is not a Solution or Outcome. Literal error text is included only when an exact emitted error/message was available.

## Attribution and provenance

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      "language": "en",
      "created_at": "2026-10-02T10:44:48.270Z",
      "revised_at": "2026-10-02T10:44:48.270Z"
    }

## Structured fields

    {
      "observed_symptom": "bug(mcp): MCP OAuth fails to obtain refresh_token and drops client_secret during background token refresh\n\nWhen configuring and using remote MCP servers that utilize OAuth 2.0 with Google endpoints (such as Google Workspace APIs like Docs, Sheets, Slides, Drive) or other confidential OAuth providers requiring a `client_secret` for token refresh:\n\n1. **No Refresh Token Issued:** On initial interactive authentication via `/mcp auth <server>`, Google's authorization server only issues a 1-hour `access_token` and **no `refresh_token`**. This occurs because `buildAuthorizationUrl` (`packages/core/src/utils/oauth-flow.ts`) constructs a generic RFC 6749 authorization URL without requesting `access_type=offline` and `prompt=consent` for Google endpoints (unlike the CLI's internal login flow in `packages/core/src/code_assist/oauth2.ts`). 2. **`client_secret` Discarded During Refresh:** When a refresh token is present, background token refresh fails against Google's token endpoint (`https://oauth2.goog",
      "context": "Public GitHub report in google-gemini/gemini-cli (FRESH_7D).",
      "environment": {
        "state": "partial",
        "text": "GitHub google-gemini/gemini-cli #29577"
      },
      "symptom_signature": {
        "literal_error_text": "packages/core/src/utils/oauth-flow.ts",
        "tool_product": "mcp"
      },
      "literal_source": "contributor_supplied",
      "expected_behavior": null
    }

## Primary and recurrence sources

    []





## Support assessment

    {
      "status": "not_applicable"
    }

## Related contributions

    []



## Source relations

    []



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## Index assessment

    {
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      "input_fingerprint": "202f361575571c15c67e4854fed08a02c6e9dff0b3651df35dbb2343ac1b22d2"
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