fix: add button title validation and base64 decode error handling

[Himanshu040604]

Summary

Fixes two bugs identified during review of #6466:

Bug 1: Missing button title length validation

• File: libs/agno/agno/tools/whatsapp.py
• ReplyButton.title used Field(description="...max 20 characters") which is
  just documentation — Pydantic does NOT enforce it. WhatsApp Cloud API rejects
  titles >20 characters with HTTP 400.
• Fix: Added max_length=20 to the Pydantic Field so validation happens
  before the API call.

Bug 2: Unhandled base64 decode crash in webhook handler

• File: libs/agno/agno/os/interfaces/whatsapp/router.py
• base64.b64decode(content) in _extract_media_bytes() crashes with
  binascii.Error when content is a non-base64 string (e.g., a file path),
  killing the entire webhook handler.
• Fix: Added try/except guard that logs a warning and returns None
  gracefully, consistent with the existing error handling pattern in the function.

Related

• Bugs found during review of feat: WhatsApp interface V2 — media I/O, interactive tools, Team/Workflow support #6466

Tests

• All 46 existing WhatsApp tests pass (23 tools + 13 security + 10 router)
• No regressions introduced

[Copilot]

Pull request overview

This PR fixes two bugs identified during review of the WhatsApp interface overhaul (#6466):

1. Missing Pydantic enforcement on ReplyButton.title — the field previously only had documentation stating "max 20 characters", but no actual constraint, so WhatsApp Cloud API would reject over-length titles at request time. Adding max_length=20 makes validation happen before any API call.
2. Unhandled binascii.Error in _extract_media_bytes() — when content is a str that is not valid base64 (e.g., a file path), calling base64.b64decode(content) would crash the webhook handler. A try/except guard now logs a warning and returns None gracefully.

Changes:

• Added max_length=20 to the Pydantic Field for ReplyButton.title to enforce the WhatsApp API constraint at the model level.
• Wrapped base64.b64decode(content) in _extract_media_bytes() with a try/except block that logs a warning and returns None on invalid base64 input.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
libs/agno/agno/tools/whatsapp.py	Adds max_length=20 to ReplyButton.title Field to enforce WhatsApp's title character limit at the Pydantic model level
libs/agno/agno/os/interfaces/whatsapp/router.py	Guards base64.b64decode() in _extract_media_bytes() for the str branch against invalid base64 input, logging a warning and returning None instead of crashing

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[Copilot]

The new max_length=20 constraint on ReplyButton.title is not covered by any test. The existing test suite is comprehensive (other boundary conditions like test_send_reply_buttons_max_3 are tested), and this validation fix is the primary code change in whatsapp.py. A test should be added that constructs a ReplyButton with a title longer than 20 characters and asserts that Pydantic raises a ValidationError.

[Copilot]

The base64 decode error handling fix in _extract_media_bytes() for the str branch is not covered by any test. The PR description identifies this as a crash fix for a previously unhandled case. A unit test should be added that passes a mock media_obj whose .content is a non-base64 string (e.g., a file path like "/tmp/audio.mp3") and verifies that the function returns None without raising.

[VirusDumb]

lgtm @Mustafa-Esoofally @uzaxirr any reviews from you before we merge?
(apart from tests)