fix(flags): Use project id for flags hypercache key

[haacked]

Problem

The flags hypercache uses the team id in the cache key. It should be the project id. In practice this is not an issue because these values are the same, but maybe sometime in the future, they will not be.

Changes

Changed the way we build the key to use the project id.

How did you test this code?

Unit Tests

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Changelog: (features only) Is this feature complete?

[greptile-apps]

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[greptile-apps]

logic: potential inconsistency: when an integer is passed as key, it's used directly in the cache key. but when a Team object is passed, project_id is used. if callers mix passing team.id (integer) vs Team objects, they could reference different cache entries if team.id != team.project_id

consider one of:

1. always normalize integer keys to project_id via Team.objects.get(id=key).project_id
2. update docstring to clarify callers must pass project_id integers, not team.id

Prompt To Fix With AI

This is a comment left during a code review.
Path: posthog/storage/hypercache.py
Line: 126:126

Comment:
**logic:** potential inconsistency: when an integer is passed as `key`, it's used directly in the cache key. but when a `Team` object is passed, `project_id` is used. if callers mix passing `team.id` (integer) vs `Team` objects, they could reference different cache entries if `team.id != team.project_id`

consider one of:
1. always normalize integer keys to project_id via `Team.objects.get(id=key).project_id`
2. update docstring to clarify callers must pass `project_id` integers, not `team.id`

How can I resolve this? If you propose a fix, please make it concise.

[Copilot]

Pull request overview

This PR updates the flags hypercache to use project_id instead of team_id in cache keys, aligning the implementation with the semantic meaning of the cached data and future-proofing for when these IDs might differ.

• Changed get_cache_key method to extract project_id from Team objects instead of id
• Updated documentation comment to reflect that project_id is used as the cache key

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
posthog/storage/hypercache.py	Modified get_cache_key to use team.project_id instead of team.id when a Team object is passed
posthog/models/feature_flag/flags_cache.py	Updated documentation comment to clarify cache key uses project_id

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