Changed main E2E tests to run across ten shards

[9larsons]

Summary

• changes the main browser E2E matrix from 8 shards to 10 shards
• leaves analytics E2E at 2 shards
• keeps TEST_WORKERS_COUNT=1 unchanged

Expected impact

Historic successful CI runs show the current main E2E split is consistently bottlenecked by one or two slow shards:

Current shard	Avg total	Avg setup	Avg test
Main 2/8	11m08s	1m56s	9m12s
Main 6/8	9m52s	2m09s	7m43s
Main 8/8	9m24s	1m58s	7m26s

Average main-shard setup is about 2m, so adding two shards adds roughly 4m of total runner setup, but wall-clock can improve if the slowest Playwright shard drops by more than the fixed setup cost on that lane.

Expected wall-clock saving: likely 1-2 minutes if Playwright's native file/test grouping spreads the current long shard better; best case is larger, but unlikely because the suite is not fullyParallel and large files remain chunky.

Success criteria

Compare this PR's E2E matrix with recent baseline runs and check:

• max main shard duration drops from ~11-12m to ~9-10m
• total E2E runner minutes do not grow disproportionately
• no increase in E2E flakes or retries

If this only moves the bottleneck, the next better step is splitting or manually binning the large files instead of adding more shards.

Testing

• not run locally; workflow matrix experiment

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

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Review profile: CHILL

Plan: Pro

Run ID: 3fd86a01-71b7-4d74-a1f4-388424c23bc3

📥 Commits

Reviewing files that changed from the base of the PR and between 88d5d08 and 88aab93.

📒 Files selected for processing (1)

• .github/workflows/ci.yml

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Walkthrough

The CI workflow in .github/workflows/ci.yml was updated to expand E2E test parallelization for the Main Playwright project. The job_e2e_tests matrix shard configuration was modified to increase shardTotal from 8 to 10, with corresponding matrix entries now covering shards 2 through 10. This adds two new shard indices (9 and 10) to the test matrix. The Analytics project sharding configuration remains unchanged at shardTotal: 2.

Possibly related PRs

• TryGhost/Ghost#27654: Modifies .github/workflows/ci.yml job_e2e_tests sharding matrix for Playwright Main lane, directly related to the shard enumeration changes in this PR.
• TryGhost/Ghost#28001: Modifies the GitHub Actions E2E workflow in .github/workflows/ci.yml to gate job execution, directly impacting the same E2E test job behavior.

Suggested reviewers

• rob-ghost

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title directly and accurately summarizes the main change: updating the main E2E test matrix from 8 shards to 10 shards.
Description check	✅ Passed	The description is clearly related to the changeset, providing detailed context about the shard configuration change, expected impact, success criteria, and rationale.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/e2e-main-10-shards

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.81%. Comparing base (88d5d08) to head (88aab93).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #28079   +/-   ##
=======================================
  Coverage   73.80%   73.81%           
=======================================
  Files        1528     1528           
  Lines      129417   129417           
  Branches    15504    15506    +2     
=======================================
+ Hits        95521    95528    +7     
+ Misses      32917    32910    -7     
  Partials      979      979           

Flag	Coverage Δ
admin-tests	54.04% <ø> (+<0.01%)	⬆️
e2e-tests	73.81% <ø> (+<0.01%)	⬆️

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