- Stop loading agent/model-spec config server-side (closes the agent-access
IDOR and the spec-prompt special-casing). Provider/model/window now come from
the client-resolved request (`limits.endpoint`/model — the agent's real
provider, not the `agents` endpoint, so the tokenizer is right). Agent/spec/
promptPrefix instructions are uniformly deferred to the full-fidelity follow-up.
- Detect summarized branches via the live path's `metadata.summaryUsedTokens`
marker (was the wrong `summaryTokenCount` field) and fall back to the
summary-aware estimate.
- Invalidate the projection query on in-place message edits via a branch
content `revision` in the cache key (the tail id is unchanged on edit).
Deferred (valid, not a regression): same-window endpoint/model switch keeps a
window-matched snapshot — needs endpoint/model persisted on the snapshot, which
lands with the fidelity follow-up. Smoke-tested: fits / prunes / summarized→null
/ no-window→null.
- Guard `currentActive` against a stale window: a model/window switch on the
current branch left the live snapshot outranking the projection (G1 didn't
fire). Now defers to the projection unless streaming or the window matches.
- Scope branch lookups to the authenticated user (`getMessages` filter +
injected `userId`) — was loading any conversation by id (IDOR).
- Recount messages with no stored `tokenCount` via the tokenizer instead of
charging 0, so snapshot-less/imported histories don't under-report.
- Fall back (null) for already-summarized branches rather than projecting from
the full raw parent chain (the next call would send summary + tail); the
client's summary-baseline-aware estimate handles them until a follow-up
replays the summary boundary.
POST /api/endpoints/context-projection → resolveContextProjection (packages/api):
reconstructs the viewed branch (parent-chain walk from messageId), resolves the
agent config (instructions/provider/model/maxContextTokens), reuses LibreChat's
stored per-message tokenCounts as the index map (no re-tokenizing), and calls
the agents SDK projectAgentContextUsage — no model call. Thin controller injects
db.getMessages/db.getAgent; route mirrors /token-config.
First cut targets message-windowing accuracy; tool-schema tokens are deferred to
a follow-up that reuses the full initializeAgent path.
