Fix Teams 413 error: add charset=utf-8 to Content-Type header and retry on 413

[devin-ai-integration]

Summary

Fixes persistent HTTP 413 (Request Entity Too Large) errors from Microsoft Teams webhooks, even after the payload truncation logic from #2160.

Root cause: The Teams webhook connector converts the request body to UTF-16 when charset is not specified in the Content-Type header, effectively doubling the payload size before enforcing the 28KB limit. A 14KB payload becomes ~28KB after conversion, triggering a 413. (Source)

Changes:

1. Set Content-Type: application/json; charset=utf-8 so the connector skips the UTF-16 conversion
2. Added a retry safety net: if Teams still returns a 413 in the response body (old webhook connectors return HTTP 200 with error text), retry once with a minimal card

Review & Testing Checklist for Human

• Verify the charset=utf-8 fix works with Prendio's specific webhook type (old O365 connector vs new Power Automate workflow webhook — behavior may differ)
• Check that the "413" in response.text substring match won't false-positive on legitimate response text from Teams
• Confirm that the retry's _minimal_card(card) fallback produces a payload small enough for Teams in all cases (it uses **card which preserves non-body fields)
• Trigger or wait for the next Prendio DAG run after deployment and verify alerts are delivered successfully

Notes

• The charset fix is based on community findings (SO answer), not official Microsoft documentation. It should be monitored after deployment.
• If the retry also fails with a 413-in-body response, it falls through to the existing error handling in send_message — no behavior regression.
• No unit tests were added; the fix is best validated by a production run against the Prendio webhook.

Link to Devin session: https://app.devin.ai/sessions/d746de1f2743489995cc5070957c91c6

Summary by CodeRabbit

• Bug Fixes
  • Improved Teams messaging integration to automatically retry with a compact card format when service responses indicate payload-size issues, increasing delivery reliability.
  • Added request timeouts to avoid long waits and ensured UTF-8 content encoding in outgoing requests for better compatibility.

[devin-ai-integration]

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Please make sure to add tests and document all user-facing changes.
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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: ba3516b1-3859-4d7c-aa1f-7d02c28bf195

📥 Commits

Reviewing files that changed from the base of the PR and between a715f67 and 49a3dbd.

📒 Files selected for processing (1)

• elementary/messages/messaging_integrations/teams_webhook.py

🚧 Files skipped from review as they are similar to previous changes (1)

• elementary/messages/messaging_integrations/teams_webhook.py

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📝 Walkthrough

Walkthrough

The Teams webhook handler now sets Content-Type: application/json; charset=utf-8, applies a request timeout, and retries with a minimal AdaptiveCard payload if an HTTP 200 response body contains "413", logging a warning before the retry. (50 words)

Changes

Cohort / File(s)	Summary
Teams Webhook Error Handling elementary/messages/messaging_integrations/teams_webhook.py	Added REQUEST_TIMEOUT_SECONDS and applied timeout to requests.post. Updated Content-Type to include charset=utf-8. Changed _minimal_card to explicitly set "type": "AdaptiveCard" and "version". After a successful initial POST, if response is 200, response body length > 1, and contains "413", log a warning and resend with a minimal-card payload; retry response is returned.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 I tapped the webhook, hopeful and bright,
The server sighed "413" in the night,
I trimmed the card, set UTF-8 neat,
I retried with patience — message complete! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title directly and specifically describes the main changes: adding charset=utf-8 to Content-Type header and implementing a retry mechanism for 413 errors in Teams webhook integration.

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✨ Finishing Touches

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🧪 Generate unit tests (beta)

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• Commit unit tests in branch devin/1774046106-fix-teams-413-charset

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@elementary/messages/messaging_integrations/teams_webhook.py`:
- Around line 122-123: The retry payload still contains large top-level fields
because _minimal_card(card) clones the entire original card and only swaps out
body; change _minimal_card to build and return a brand-new minimal dict (do not
copy the original) that includes only the small required keys (e.g., card
type/summary/title if needed) plus the new body, ensuring any large fields from
the original card are omitted before calling _build_payload; update callers
using _minimal_card(card) accordingly so payload only contains those minimal
keys.
- Around line 107-128: The two requests.post calls that send Teams webhooks (the
initial call and the retry in the branch that builds a minimal card) lack an
explicit timeout and can block indefinitely; update both calls to pass a
reasonable timeout value (e.g. timeout=5 or a configured constant) to
requests.post so the worker won't hang, and ensure the same timeout constant is
used for both the initial send and the retry paths that call _build_payload and
_minimal_card.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 72f4a384-745c-4c03-816c-fd7c00202f35

📥 Commits

Reviewing files that changed from the base of the PR and between ed170b7 and a715f67.

📒 Files selected for processing (1)

• elementary/messages/messaging_integrations/teams_webhook.py