fix(tasks): bound imported MCP server DNS validation

[richardsolomou]

Problem

Imported MCP server validation could let slow DNS lookups occupy request workers without a shared deadline.

Changes

Bound lookup time and global admission, give all accepted hosts a lookup slot, deduplicate hosts, and reject oversized lists before DNS work.

How did you test this code?

• uv run hogli test posthog/security/test/test_url_validation.py
• uv run hogli test products/tasks/backend/tests/test_presentation_serializers.py
• uv run mypy posthog/security/url_validation.py products/tasks/backend/presentation/serializers.py; OpenAPI generation and preflight also pass.

👉 Stay up-to-date with PostHog coding conventions for a smoother review.

Automatic notifications

• Publish to changelog?
• Alert Sales and Marketing teams?

Docs update

N/A. This changes internal validation behavior without changing the documented API.

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

I used PostHog Code with /rs-address-pr-review, /rs-review-swarm, /improving-drf-endpoints, /implementing-mcp-tools, /writing-tests, and /setup-web-tests. The swarm caught executor queueing and worker-wave edge cases, which are covered by deterministic regression tests.

---

Created with PostHog Code

[github-actions]

Hey @richardsolomou! 👋

It looks like your git author email on this PR isn't your @posthog.com address (richard@solomou.dev). Since you're on the PostHog team, it's worth pointing your local git author email at your @posthog.com address. Why it matters:

• Consistent work identity in git history — internal tooling that attributes commits to team members keys off your @posthog.com address.
• Keeps team contributions easy to tell apart from external community ones when scanning history.

You can fix it for this repo with:

git config user.email "you@posthog.com"

Or set it globally with git config --global user.email "you@posthog.com". No need to redo this PR — just a nudge for next time. 🙂

[trunk-io]

     

View Full Report ↗︎ ⋅ Docs

[greptile-apps]

_{Reviews (1): Last reviewed commit: "fix(tasks): bound DNS resolution admissi..." | Re-trigger Greptile}

[github-actions]

🤖 CI report

✅ Playwright — all passed

All tests passed.

View test results →

⚠️ Backend coverage — 91.0% of changed backend lines covered — 13 uncovered

🧪 Backend test coverage

Patch coverage — changed backend lines (products + core): ██████████████████░░ 91.0% (137 / 150)

File	Patch	Uncovered changed lines
posthog/security/url_validation.py	83.6%	80–83, 107–109, 185, 189, 193–194, 203
posthog/security/test/test_url_validation.py	98.0%	80

🤖 Agents: add a test covering the lines above, or note why under "How did you test this code?". Machine-readable gap list: the patch-coverage artifact on this run (gh run download 29487966912 -n patch-coverage), or the coverage-data block at the end of this comment.

Per-product line coverage (touched products)

Product	Coverage	Lines
platform_features	██░░░░░░░░░░░░░░░░░░ 12.1%	7 / 58
batch_exports	████████░░░░░░░░░░░░ 39.7%	8,414 / 21,220
demo	███████████░░░░░░░░░ 56.2%	1,497 / 2,663
warehouse_sources_queue	████████████░░░░░░░░ 59.2%	148 / 250
tasks	█████████████░░░░░░░ 67.4%	25,804 / 38,268
data_tools	██████████████░░░░░░ 70.0%	63 / 90
ai_gateway	███████████████░░░░░ 75.0%	9 / 12
signals	████████████████░░░░ 79.1%	19,035 / 24,073
data_modeling	████████████████░░░░ 80.0%	4,834 / 6,045
cdp	████████████████░░░░ 80.7%	3,118 / 3,864
wizard	████████████████░░░░ 82.5%	772 / 936
notebooks	█████████████████░░░ 84.3%	6,343 / 7,520
agent_platform	█████████████████░░░ 84.7%	3,273 / 3,862
cohorts	█████████████████░░░ 86.1%	4,022 / 4,671
actions	█████████████████░░░ 86.6%	717 / 828
product_tours	█████████████████░░░ 87.5%	1,266 / 1,447
exports	██████████████████░░ 88.3%	6,891 / 7,800
visual_review	██████████████████░░ 88.5%	5,565 / 6,287
business_knowledge	██████████████████░░ 88.5%	4,400 / 4,969
conversations	██████████████████░░ 88.9%	16,129 / 18,133
dashboards	██████████████████░░ 89.1%	5,719 / 6,418
mcp_analytics	██████████████████░░ 89.1%	2,502 / 2,807
error_tracking	██████████████████░░ 89.6%	9,738 / 10,872
alerts	██████████████████░░ 89.9%	3,638 / 4,046
engineering_analytics	██████████████████░░ 90.1%	5,105 / 5,665
streamlit_apps	██████████████████░░ 90.4%	2,499 / 2,764
slack_app	██████████████████░░ 90.6%	9,511 / 10,503
links	██████████████████░░ 90.6%	183 / 202
marketing_analytics	██████████████████░░ 90.8%	11,514 / 12,684
product_analytics	██████████████████░░ 91.1%	5,599 / 6,143
mcp_store	██████████████████░░ 91.8%	3,668 / 3,995
managed_migrations	██████████████████░░ 91.9%	908 / 988
data_warehouse	██████████████████░░ 92.1%	18,133 / 19,683
workflows	██████████████████░░ 92.4%	5,148 / 5,574
notifications	███████████████████░ 92.7%	1,026 / 1,107
web_analytics	███████████████████░ 92.7%	13,624 / 14,691
ai_observability	███████████████████░ 92.8%	14,868 / 16,019
surveys	███████████████████░ 92.9%	5,687 / 6,120
posthog_ai	███████████████████░ 93.2%	1,322 / 1,418
tracing	███████████████████░ 93.3%	2,435 / 2,611
approvals	███████████████████░ 93.3%	3,395 / 3,640
reminders	███████████████████░ 93.4%	468 / 501
early_access_features	███████████████████░ 93.8%	848 / 904
legal_documents	███████████████████░ 94.1%	1,568 / 1,667
endpoints	███████████████████░ 94.1%	8,606 / 9,143
skills	███████████████████░ 94.4%	2,827 / 2,995
revenue_analytics	███████████████████░ 94.5%	3,598 / 3,809
messaging	███████████████████░ 94.5%	2,530 / 2,677
review_hog	███████████████████░ 94.6%	6,532 / 6,905
logs	███████████████████░ 95.3%	9,528 / 9,994
experiments	███████████████████░ 95.6%	24,179 / 25,296
replay_vision	███████████████████░ 95.7%	13,354 / 13,952
growth	███████████████████░ 95.8%	2,837 / 2,960
annotations	███████████████████░ 96.2%	732 / 761
feature_flags	███████████████████░ 96.3%	16,118 / 16,741
warehouse_sources	███████████████████░ 96.3%	237,728 / 246,902
user_interviews	███████████████████░ 96.4%	2,242 / 2,325
access_control	███████████████████░ 96.8%	849 / 877
data_catalog	███████████████████░ 97.1%	2,034 / 2,095
customer_analytics	███████████████████░ 97.2%	7,480 / 7,698
analytics_platform	████████████████████ 98.0%	2,102 / 2,145
metrics	████████████████████ 98.2%	2,404 / 2,448
live_debugger	████████████████████ 99.2%	613 / 618
field_notes	████████████████████ 99.4%	158 / 159

Report-only. Patch coverage = changed backend lines covered vs origin/master. Sorted lowest first.
Known gaps: lines covered only by Temporal tests show as uncovered; core line numbers may drift if master changed the same file.

[deployment-status-posthog]

Deploy status

Environment	Status	Deployed At	Workflow
dev	✅ Deployed	2026-07-16 10:49 UTC	Run
prod-us	✅ Deployed	2026-07-16 11:06 UTC	Run
prod-eu	✅ Deployed	2026-07-16 11:05 UTC	Run