fix(auth): reject ambiguous conversation widget tokens

[pauldambra]

[Robot] Prepared by PostHog Desktop.

Problem

A widget token that matches more than one project causes a server error.

Changes

Reject an ambiguous token with an authentication error.

This fixes existing behavior before the module split in #99248.

How did you test this code?

Parameterized authentication tests cover missing and duplicate tokens. The focused tests ran against both module layouts. The full type check covers the combined fixes.

Release status

• No feature flag controls this change

Automatic notifications

• Publish to changelog?

Docs update

No existing document under docs/ covers this validation detail.

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Agent: PostHog Desktop / Codex, GPT-6

Tools: Git, GitHub CLI, hogli, pytest, Ruff, mypy, and CodeRabbit.
Skills: stacking-prs, improving-drf-endpoints, writing-tests, writing-code-comments, writing-user-facing-copy, setting-up-devbox, running-ci-preflight, reviewing-with-coderabbit, writing-pr-descriptions.
Each existing bug has its own layer below the refactor. No matching open fix appeared in the PR search.
The combined CodeRabbit review found two deployment tradeoffs in the membership layer. That PR records the decisions.

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Created with PostHog Desktop

[posthog]

FLASH MODE - Faster, but stupid, use regular ReviewHog for a heavy review

🦔 PostHog Review reviewed this pull request

Nothing worth raising this time. Enjoy the moment:

[github-actions]

🤖 CI report

⚠️ Trunk lane — backend Python lane

This PR is assigned to the backend Python lane. It runs backend Python tests and may merge in parallel with PRs in other lanes.

⚠️ Duplication (Python) — 11 new duplicated blocks (worst 203 tokens)

New Python code duplication introduced by this branch. Fails at 70+ tokens in app code, or 150+ tokens when both copies live in test files. Advisory while the gate proves itself: extract a shared helper instead of copying.

First copy	Second copy	Lines	Tokens
posthog/temporal/ai_observability/run_aggregate_evaluation.py:692	posthog/temporal/ai_observability/run_trace_evaluation.py:928	38	203
products/warehouse_sources/backend/temporal/data_imports/sources/companycam/source.py:1	products/warehouse_sources/backend/temporal/data_imports/sources/wix/source.py:1	21	164
posthog/temporal/ai_observability/run_aggregate_evaluation.py:584	posthog/temporal/ai_observability/run_trace_evaluation.py:855	24	135
products/signals/backend/scout_harness/tools/report.py:1475	products/signals/backend/scout_harness/tools/report.py:1647	21	133
products/signals/backend/scout_harness/tools/report.py:1604	products/signals/backend/scout_harness/tools/report.py:1754	30	118
posthog/temporal/ai_observability/run_session_evaluation.py:466	posthog/temporal/ai_observability/run_trace_evaluation.py:664	24	115
posthog/management/commands/backfill_hogflow_billable_action_types.py:49	posthog/management/commands/refresh_hog_flows.py:69	23	112
products/batch_exports/backend/api/batch_export.py:2092	products/batch_exports/backend/api/batch_export.py:2131	24	112
products/warehouse_sources/backend/temporal/data_imports/sources/pardot/pardot.py:2	products/warehouse_sources/backend/temporal/data_imports/sources/wix/wix.py:1	12	97
products/signals/backend/scout_harness/tools/report.py:1516	products/signals/backend/scout_harness/tools/report.py:1675	12	71
products/signals/backend/scout_harness/tools/report.py:1531	products/signals/backend/scout_harness/tools/report.py:1690	16	70

⚠️ Duplication (TypeScript) — 2 new duplicated blocks (worst 158 tokens)

New TypeScript code duplication introduced by this branch. Fails at 70+ tokens in app code, or 150+ tokens when both copies live in test files. Advisory while the gate proves itself: extract a shared helper instead of copying.

First copy	Second copy	Lines	Tokens
products/business_knowledge/frontend/scenes/settings/businessKnowledgeSettingsLogic.test.ts:10	products/data_catalog/frontend/certificationsLogic.test.ts:17	23	158
products/business_knowledge/frontend/scenes/settings/businessKnowledgeSettingsLogic.test.ts:10	products/data_quality/frontend/dataQualityGateLogic.test.ts:14	23	158

✅ Playwright — all passed

All tests passed.

View test results →

[coderabbitai]

Navigate logical layers of code changes, visualize relationships, and explore their blast radius.

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository: PostHog/posthog/.coderabbit.yaml

Review profile: QUIET

Plan: Enterprise

Run ID: 9858eda6-3c7e-43ce-b870-724300bd26fc

📥 Commits

Reviewing files that changed from the base of the PR and between f696fcc and 258376d.

📒 Files selected for processing (2)

• posthog/api/test/test_authentication.py
• posthog/auth.py

Included review availability: This review used your included allowance. Your plan provides up to 12 included reviews per hour; 9 remain after this review.

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📝 Walkthrough

Walkthrough

WidgetAuthentication now raises AuthenticationFailed when team lookup raises Team.DoesNotExist or Team.MultipleObjectsReturned. A parameterized test checks both cases.

Priority: ⬇️ Low

Merge Risk: ⚪ Minimal · up to 25837

Ambiguous widget tokens now fail authentication instead of surfacing an unhandled lookup exception; missing-token behavior and successful authentication remain unchanged. No concrete merge-blocking risk remains in the supplied changes.

Security Architecture Review

Security architecture risk: 🔵 Low · up to 25837

The change rejects ambiguous tokens instead of granting access to either matching team. No new access path was identified, but the exact HTTP response and behavior across every widget endpoint were not verified.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — Because the lookup selects a team by token rather than by a caller-supplied tenant identifier, a collision can affect authentication for the matching teams. This change rejects that ambiguous identity rather than selecting one.

Trust Boundaries and Controls

• observed — An ambiguous token is stopped at authentication before a team is returned to the widget consumer. The inspected consumer's separate session controls are unchanged.

🚥 Pre-merge checks | ✅ 1

✅ Passed checks (1 passed)

Check name	Status	Explanation
Description check	✅ Passed	The description covers the problem, behavior change, testing, release status, documentation impact, and agent context. The Agent context includes the required tools and skills, but it does not provide…

✨ Finishing Touches

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• Create a new PR

🧪 Generate unit tests (beta)

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[trunk-io]

   

View Full Report ↗︎ ⋅ Docs

[posthog-security-review-bot]

✅ Security review complete — 39278a5adbd3

1 finding posted as a review, in 11 min.

_{Add the security-review label to run again on the latest commit.}

[pauldambra]

[Robot]

Note

🤖 Automated comment by QA Swarm — not written by a human

Verdict: APPROVE _{(round 1 @ 39278a5)}

No actionable findings. Ambiguous widget tokens fail authentication instead of causing a server error.

Key findings

• The parameterized test covers missing and duplicate token results. Both cases passed.

Convergence

Both reviewers found no correctness or security defects.

Reviewer summaries

Reviewer	Assessment
Router (gpt-5.6-sol)	Reviewed the complete patch. Authentication requires a second review.
Auth validator (gpt-6-astra)	Confirmed that duplicate tokens cannot select or expose a team.

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Automated by QA Swarm — not a human review

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-29T12:51:27.475918Z	39278a5	Draft marked ready

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[stamphog]

Not approved yet — waiting on the conditions below.

Re-add the stamphog label to request another review once you have addressed this.

stamphog can't approve this pull request because two gates refused it. The deny-list gate flagged it for matching the auth category, since it changes posthog/auth.py and adds tests for authentication. The tier gate classified it as T2-never (12 lines, 2 files, single-area fix), a tier that is never eligible for automated approval. The size gate passed, so splitting the PR won't change the outcome. Please ask a human reviewer, ideally someone who owns authentication, to review it.

• 👍 on the PR from chatgpt-codex-connector[bot].

Gate mechanics and policy version

Gate		Result
prerequisites	✓	all clear
deny-list	✗	matches: auth
size	✓	2L, 1F substantive, 12L/2F incl. docs/generated/snapshots — within ceiling
tier	✗	classified as T2-never: T2-never (12L, 2F, single-area, fix)
stamphog 2.3.0		.stamphog/policy.yml @ unknown · reviewed head 39278a5

[posthog-security-review-bot]

Agent-driven security review - findings inline.