Pydantic Use Sphinx inventory references in docs (Fix)

The Fix

pip install pydantic==2.6.2

Based on closed pydantic/pydantic issue #8664 · PR/commit linked

Open PR/Commit

@@ -51,7 +51,7 @@ except ValidationError as e:
 types:
 
-### `datetime.datetime`
+### [`datetime.datetime`][]
 * `datetime` fields will accept values of type:

fix.md

Option A — Upgrade to fixed release\npip install pydantic==2.6.2\nWhen NOT to use: This fix is not applicable if the documentation does not require Sphinx inventory support.\n\n

Why This Fix Works in Production

Trigger: - [ ] [Compatibility between releases](https://docs.pydantic.dev/changelog/)
Mechanism: The documentation lacked support for Sphinx inventories, making external references unclear
Why the fix works: Adds support for Sphinx inventories in the documentation, enhancing cross-references for Python objects. (first fixed release: 2.6.2).

Why This Breaks in Prod

The documentation lacked support for Sphinx inventories, making external references unclear
Production symptom (often without a traceback): - [ ] [Compatibility between releases](https://docs.pydantic.dev/changelog/)

Proof / Evidence

GitHub issue: #8664
Fix PR: https://github.com/pydantic/pydantic/pull/8682
First fixed release: 2.6.2
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.95
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.78

Discussion

High-signal excerpts from the issue thread (symptoms, repros, edge-cases).

Jump to Sources Open on GitHub

“Great if we can do it, but I think it'll require changes to mkdocstrings.”

@samuelcolvin · 2024-01-29 · source

“What changes are you thinking about? Afaik it supports most of it, apart from specific sphinx domains”

@Viicos · 2024-01-29 · source

Failure Signature (Search String)

- [ ] [Compatibility between releases](https://docs.pydantic.dev/changelog/)
- [ ] [Data validation/parsing](https://docs.pydantic.dev/concepts/models/#basic-model-usage)

Copy-friendly signature

signature.txt

Failure Signature
-----------------
- [ ] [Compatibility between releases](https://docs.pydantic.dev/changelog/)
- [ ] [Data validation/parsing](https://docs.pydantic.dev/concepts/models/#basic-model-usage)

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
- [ ] [Compatibility between releases](https://docs.pydantic.dev/changelog/)
- [ ] [Data validation/parsing](https://docs.pydantic.dev/concepts/models/#basic-model-usage)

What Broke

Users faced confusion when referencing Python objects in the documentation.

Why It Broke

The documentation lacked support for Sphinx inventories, making external references unclear

Fix Options (Details)

Option A — Upgrade to fixed release Safe default (recommended)

pip install pydantic==2.6.2

When NOT to use: This fix is not applicable if the documentation does not require Sphinx inventory support.

Use when you can deploy the upstream fix. It is usually lower-risk than long-lived workarounds.

Option D — Guard side-effects with OnceOnly Guardrail for side-effects

Mitigate duplicate external side-effects under retries/timeouts/agent loops by gating the operation before calling external systems.

Place OnceOnly between your code/agent and real side-effects (Stripe, emails, CRM, APIs).
Use a stable key per side-effect (e.g., customer_id + action + idempotency_key).
Fail-safe: configure fail-open vs fail-closed based on blast radius and spend risk.

Show example snippet (optional)

onceonly.py

from onceonly import OnceOnly
import os

once = OnceOnly(api_key=os.environ["ONCEONLY_API_KEY"], fail_open=True)

# Stable idempotency key per real side-effect.
# Use a request id / job id / webhook delivery id / Stripe event id, etc.
event_id = "evt_..."  # replace
key = f"stripe:webhook:{event_id}"

res = once.check_lock(key=key, ttl=3600)
if res.duplicate:
    return {"status": "already_processed"}

# Safe to execute the side-effect exactly once.
handle_event(event_id)

See OnceOnly SDK

When NOT to use: Do not use this to hide logic bugs or data corruption. Use it to block duplicate external side-effects and enforce tool permissions/spend caps.

Fix reference: https://github.com/pydantic/pydantic/pull/8682

First fixed release: 2.6.2

Last verified: 2026-02-09. Validate in your environment.

When NOT to Use This Fix

This fix is not applicable if the documentation does not require Sphinx inventory support.
Do not use this to hide logic bugs or data corruption. Use it to block duplicate external side-effects and enforce tool permissions/spend caps.

Did This Fix Work in Your Case?

Quick signal helps us prioritize which fixes to verify and improve.

Prevention

Add a CI check that diffs key outputs after upgrades (OpenAPI schema snapshots, JSON payload shapes, CLI output).
Upgrade behind a canary and run integration tests against the canary before 100% rollout.

Version Compatibility Table

Version	Status
2.6.2	Fixed

Related Issues

No related fixes found.

Cluster: pydantic:serialization Pydantic hub Pydantic best practices All hubs All clusters

Related clusters: Configuration error Data consistency OpenAPI schema

Sources

We don’t republish the full GitHub discussion text. Use the links above for context.