Unbounded caches in Instance and Provider modules cause memory growth

[sauerdaniel]

Problem

Several places in the codebase use unbounded Map objects for caching:

• Instance cache in project/instance.ts
• Provider SDK cache in provider/provider.ts

In long-running processes or when handling many directories/providers, these maps can grow without limit, causing steady memory growth.

Expected behavior

Caches should have a maximum size with LRU eviction so memory remains bounded, with optional cleanup callbacks for evicted entries.

Related

This is distinct from #9143 (LSP diagnostics/files cleanup, already fixed in f936043dd). This issue is about the broader pattern of unbounded Map caches elsewhere in the codebase.

[github-actions]

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This issue might be a duplicate of existing issues. Please check:

• Memory leak: Unbounded caches grow without limit #9140: Memory leak: Unbounded caches grow without limit (exact duplicate — same files and root cause)
• opencode eating 70gb of memory? #5363: Related to broader memory issues in long-running sessions
• Memory leak: Instance disposal doesn't clean up plugins or cached resources #9157: Memory leak: Instance disposal doesn't clean up plugins or cached resources (related)
• fix: multiple memory leaks in long-running sessions #10913: fix: multiple memory leaks in long-running sessions (open PR addressing this)
• Memory usage grows very quickly when running commands with large output #9699: Memory usage grows very quickly when running commands with large output (related)

Please review #9140 in particular, as it describes the exact same problem with the same proposed solution (LRU cache with eviction). If you have additional context or reproduction steps beyond what's in #9140, please add them as a comment there.

[sauerdaniel]

Closing as duplicate of #9140 to keep one issue per problem/PR scope. PR #9141 now references #9140 directly.