I think the proxy angle is genuinely appealing for the reasons you give: team-level, no per-dev install, reshape every agent's context from one place. We went down that exact fork and chose against it (wrote up the reasoning as an ADR if you want it). Instead of intercepting and rewriting prompts/tool_calls, Lore does context-supply + post-edit enforcement.

Two things drove it:

One, a proxy that silently rewrites what the agent sees is hard to audit so you can't review an injection that never lands anywhere, and when it misfires you're debugging an invisible middle layer. We wanted the injected context to be a file in the PR diff (a generated CLAUDE.md/rules file) and the rest to be explicit read tools the agent chooses to call.

Two, and this is the part I'd flag for your index, the hard problem isn't delivery, it's knowing which decision is still current. An index built from git logs + tickets + PRDs is mostly stale or contradictory text; if a call got reversed six months ago, a fuzzy index will happily re-inject the old one. So that's where we spend the complexity budget: typed, human-reviewed decisions where "superseded" is enforced in CI, so the agent never gets handed a ruling you already overturned.

Which is why I think these compose rather than compete. Your proxy is a delivery mechanism; it still needs a trustworthy source for "the decisions this team made." That's what Lore is, and it exports for exactly this — rac export --documents (JSONL) or --graph to feed an index, --agent-rules for the injection layer. Stay fuzzy and convenient at recall, point back at a deterministic source for the part that has to be exactly right. Keen to see where praxis_agent_runtime goes — provenance-first is the right instinct.