[Pre-work] Codebase cleanup before GSoC project work begins

Context

Before any new features land, there are 6 structural problems in the existing codebase that will block or corrupt downstream work if left unresolved. This issue tracks all of them.

These are not improvements — they are fixes to things that are already broken or ambiguous. Zero new features.

• Estimated: Week 1–2.

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Execution Order

The order matters. Each item either unblocks the next or can safely run in parallel.

#72 ── ADR-008 (decide storage pattern)
         ↓
       #28 ── Standardize MilvusClient across all servers
         ↓
       #73 ── Kustomize restructure          ←┐
         ↓                                    │ parallel
       #74 ── _init() race condition    ───────┘
       #75 ── httpx per-request client  ── (parallel with #73/#74)
         ↓
       #76 ── CORS tightening  (needs Kustomize overlays first)

Why this order

• ADR first — two storage patterns (store_milvus vs store_via_feast) co-exist after PR #58. Every pipeline issue downstream assumes one canonical path. Can't write that code until this decision is documented.
• MilvusClient (#28) second — server/app.py and server-https/app.py still use the legacy connections.connect() global state API. The _init() race (#74) and the 3-collection schema both inherit this bug. Fix the API first.
• Kustomize (#73) before CORS (#76) — the clean CORS fix is an env var injected per overlay (localhost in dev, production domain in OCI). Without overlays, you're hardcoding values.
• Concurrency bugs (#74, #75) before agent layer — the Kagent-managed agent layer builds directly on top of these servers. Fix races now so the agent doesn't inherit them.

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Child Issues

#	What	Depends On	Blocks
#72 (this)	ADR-008 — formalize pymilvus over Feast	—	#28, pipeline work
#28	Standardize MilvusClient across all servers	#72	#74, ISSUE-06
#73	Restructure manifests/ into Kustomize base/overlay	#28	#76, ISSUE-03/04/05
#74	Fix _init() race condition in mcp-server/server.py	#28	Kagent agent layer
#75	Fix httpx.AsyncClient per-request in server-https/app.py	#28	Kagent agent layer
#76	Replace allow_origins=["*"] with env-var allowlist	#73	ISSUE-16

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ADR-008 Task (this issue)

• PR #58 merged a Feast POC (store_via_feast()) but the project is continuing with direct pymilvus.
  The decision is implicitly made but never written down.

Action:

• Write docs/adr/ADR-008-vector-store-selection.md
• Document: context, decision (MilvusClient/pymilvus), rationale (proven,
  lighter deps, thread-safe), future path (Feast when feast[milvus] hits GA)
• Mark kagent-feast-mcp/pipelines/ as legacy/optional in a comment
• Reference ADR-008 in README.md

Acceptance Criteria

• docs/adr/ADR-008-vector-store-selection.md exists and is merged
• kagent-feast-mcp/pipelines/kubeflow-pipeline.py has a legacy comment

Child Issues

• #72
  • (this) — ADR-008: formalize pymilvus over Feast
• #28
• #73
• #74
• #75
• #76

Note: closed before project work starts

References

• PR #58 — merged Feast POC that created the ambiguity
• GSoC design discussion: #59
• ADR format reference

Read the ADR format reference and PR #58 for the storage decision context. Create docs/adr/ADR-008-vector-store-selection.md, add the requested legacy comment to kagent-feast-mcp/pipelines/kubeflow-pipeline.py, and reference the ADR in README.md. Done means the ADR exists with the listed sections and the acceptance criteria are satisfied.