W26 — v0.4 Consumer Groups, offsets and lag

[ammarheidari]

Objective

Implement bounded read-only consumer group/member/assignment/offset/lag observation.

Deliverables

• group list/describe,
• committed offsets,
• end offsets,
• partition and aggregate lag,
• bounded pagination/snapshot behavior,
• partial/ACL/timeout semantics,
• Kafka 4.3.1/4.2.1/4.1.2/3.9.2 integration coverage,
• proof of no group join and no offset mutation.

Depends on W25 stable contracts.

Central tracker: #100
Scope authority: #99 / RFC-0004.

[ammarheidari]

W26 was admitted to protected main through PR #110 at merge commit 78f579d38fe504d39153503c6f2380dcde6adf72. Exact-head quality, Kafka smoke/compatibility, CodeQL, dependency and supply-chain checks passed; review findings on missing commits, partial group listing and end-offset authorization semantics were resolved.