Add message retention related data types

[rnons]

[linear-code]

PLAT-33864

[indent]

PR Summary

Adds Slack message-retention data types so downstream consumers can read conversation-level retention policies via a regular user token and surface workspace-level retention defaults from the boot response.

• Adds ConversationRetention struct and GetConversationRetention[Context] wrapping the undocumented conversations.getRetention endpoint in conversation.go.
• Adds six new retention default fields to TeamPrefs in users.go (RetentionType/Duration, GroupRetentionType/Duration, DMRetentionType/Duration) with doc comments mapping the integer enum values.

Issues

2 potential issues found:

• New TeamPrefs retention fields are typed plain int while existing prefs (MsgEditWindowMins *int, AllowMessageDeletion *bool) use pointers, so a missing field and an explicit 0 decode identically; consider *int for consistency and to preserve the absent-vs-zero distinction. → Autofix
• The retention Type enum is documented differently in ConversationRetention (0=inherit, 1=never, 2=preset, 3=custom) vs TeamPrefs ("1=retain all, 2=delete after duration, other values mean no automatic deletion"); align the comments so callers know value 3 is possible and that 0 means "inherit". → Autofix

CI Checks

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between ff6fd25 and 077047c.

📒 Files selected for processing (2)

• conversation.go
• users.go

📜 Recent review details

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (2)

• GitHub Check: test go-1.26
• GitHub Check: test go-1.25

🔇 Additional comments (2)

conversation.go (1)

598-637: LGTM!

users.go (1)

189-199: LGTM!

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📝 Walkthrough

Summary by CodeRabbit

• New Features
  • Added support for retrieving message retention policies for conversations.
  • Extended team preferences with message retention configuration options for public channels, private groups, and direct messages.

Walkthrough

This PR extends the Slack API client with message retention support across two layers: it adds a ConversationRetention type and API methods to fetch retention policies for individual conversations, and it augments the TeamPrefs struct with retention configuration fields for public channels, private channels, and direct messages.

Changes

Message Retention Support

Layer / File(s)	Summary
Conversation retention API and types conversation.go	Introduces ConversationRetention struct with retention type and duration, and adds GetConversationRetention and GetConversationRetentionContext methods that call the conversations.getRetention Slack API endpoint and return the decoded retention policy.
Team-wide retention preference fields users.go	Extends TeamPrefs struct with six new retention fields: RetentionType, RetentionDuration for public channels, GroupRetentionType, GroupRetentionDuration for private channels, and DMRetentionType, DMRetentionDuration for DMs/MPIMs.

🎯 2 (Simple) | ⏱️ ~8 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The PR description consists only of a screenshot image with no textual explanation of changes, objectives, or adherence to repository guidelines.	Provide a detailed written description following the repository template, including rationale for API changes, test status, and answers to the PR preparation checklist items.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately reflects the main changes: adding ConversationRetention struct and TeamPrefs retention fields.
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 docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch rnons/plat-33864

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[indent]

Type inconsistency with surrounding TeamPrefs fields: the existing prefs in this struct use pointer types (*int, *bool) so callers can distinguish an absent field from a zero value. The new retention fields use plain int with omitempty, which means a JSON payload that omits e.g. retention_type is indistinguishable from one that sends 0. Per your own doc comment, value 0 is meaningful (other values mean no automatic deletion), so an unset field and an explicit unset look the same to callers. Consider matching the existing style with *int for symmetry and to preserve the absent-vs-zero signal.

[indent]

Doc inconsistency with ConversationRetention.Type: the comment over in conversation.go enumerates 0/1/2/3 with concrete meanings (0=inherit workspace default, 3=custom timeline), but here "other values" is left vague. Since both fields are decoding the same Slack retention enum it would be clearer to use the same enumeration here so callers know about the 3 and 0 cases.