refactor(config): use generic cache for SegmentWriter

[Mertozturkk]

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Description

This is a reworked version of #7308, which was unintentionally closed during a base branch rebase. The changes have been rebased onto the latest main and address all review feedback from the previous PR.

Refactored the segment caching mechanism to use generic types instead of JSON serialization, resolving the TODO in setCache.

Changes:

• Replaced json.Marshal/json.Unmarshal with cache.Get[SegmentWriter] and cache.Set for direct interface storage
• Added graceful handling of legacy string cache entries (deletes old keys without error-level logging)
• Added TestSegmentCache unit test covering both generic cache and legacy data migration
• Added defer cache.DeleteAll to prevent test state leakage

[Copilot]

Pull request overview

Refactors segment caching in config.Segment to store and restore SegmentWriter values directly via the generic cache API (instead of JSON serialization), while attempting to migrate legacy string cache entries.

Changes:

• Switch segment cache storage from json.Marshal/json.Unmarshal to cache.Set/cache.Get[SegmentWriter].
• Add legacy-cache detection that deletes string cache entries so they can be regenerated.
• Add a unit test covering writer restoration and legacy-entry deletion.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/config/segment.go	Updates segment cache restore/set logic to use typed cache storage and adds legacy string cleanup.
src/config/segment_cache_test.go	Adds a unit test for segment cache restore and legacy key removal.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

[luisdavim]

don't we want to keep this?

[Mertozturkk]

That check was accidentally removed during the refactor. I've restored it to ensure we don't pollute the cache with incomplete data when a segment is still in a pending state. Re-pushed the fix

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

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

Comments suppressed due to low confidence (1)

src/config/segment.go:377

• Segment cache entries now store gob-encoded []byte under the existing "segment_cache_%s" keys. This changes the value type in-place, which can make troubleshooting/downgrades noisier (older versions expecting a JSON string will see a type mismatch/unmarshal failure in debug logs and won’t self-heal). Consider versioning/namespacing the cache key (e.g., "segment_cache_v2_%s") so different on-disk formats can coexist and upgrades/downgrades degrade to a cache miss instead of repeated decode errors.

func (segment *Segment) cacheKeyAndStore() (string, cache.Store) {
	format := "segment_cache_%s"
	switch segment.Cache.Strategy {
	case Session:
		return fmt.Sprintf(format, segment.Name()), cache.Session
	case Device:
		return fmt.Sprintf(format, segment.Name()), cache.Device
	case Folder:
		fallthrough
	default:
		return fmt.Sprintf(format, strings.Join([]string{segment.Name(), segment.folderKey()}, "_")), cache.Device
	}

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[JanDeDobbeleer]

@Mertozturkk this breaks when in streaming mode, didn't look at the details just yet but I can make the prompt fail now. I pushed the udpated branch, maybe I missed something silly.