The first checkpoint removed terminal-metrics discovery, but a normal
compact chat turn still ran two context systems: build_chat_context's
legacy untyped lookup (directly or inside maybe_compact) and the typed
resolver inside stream_preview.
Resolve the typed ContextResolution once, at the chat route, before
build_chat_context, using the session's provider credentials. The
predicate mirrors _clean_v3_preview; every input it needs is known at
that point and the native-workspace term cannot veto a requested clean
route. The same object then:
- sizes legacy history shaping in build_chat_context through a new
maybe_compact(context_length=...) override, so no legacy probe runs;
an unknown window still shapes with DEFAULT_CONTEXT but gains no
provenance;
- crosses stream_agent_loop (one new parameter, forwarded only at the
compact dispatch) into stream_preview, which reuses it and probes only
for callers that arrive without one or with one bound to another
route.
ContextResolution now records the endpoint and model it describes
(endpoint URL excluded from repr and metrics). The bare legacy
context_length is never converted into typed evidence.
Credential scoping: origins compare with default ports normalized, an
empty host is never trusted, and the probe client never follows
redirects. Tests cover the configured origin, the server-resolved
Tailscale form, scheme/port/lookalike/userinfo/path origins, redirects,
and secret-free errors, logs and metrics.
The conftest guard now replaces only the resolver's I/O edges (HTTP
client and DNS-capable URL building) instead of the whole probe, and
exposes a context_probe_ledger fixture, so route integration tests run
the real resolver offline and can count metadata requests.
The compact (clean v3) runtime had no effective context window: it learned a
limit only reactively from a provider 400/413 and its terminal metrics carried
no context_length. PR #41 addressed the reporting gap by probing provider
metadata between the last model byte and [DONE], unauthenticated, and folded
known-table and endpoint evidence into one "known" flag.
Resolve the window once, before the first model request, instead:
- src/agent_runtime/context_resolution.py adds a typed ContextResolution
(effective value, evidence class, source, all observations, conflicts,
provider_io, cached, secret-free probe errors). Evidence classes stay
distinct: runtime_confirmed (llama.cpp /slots, /props, or a limit the
provider stated this turn), provider_advertised (models catalog),
operator_declared (client_runtime_context.model_context_window),
known_table, unknown (0, never a default).
- Selection is deterministic: runtime beats provider beats table; an
operator declaration caps measured evidence and replaces weaker evidence.
Disagreements are recorded as conflicts; a declaration below a measured
value is a cap, above it a contradiction.
- The provider probe forwards the turn's credentials only to the provider's
own origin, runs URL resolution off the event loop, is bounded by one
deadline, never raises, and caches remote results per credential
fingerprint (shorter TTL for failures; local servers are re-probed).
- stream_preview resolves at preparation (or accepts a supplied resolution),
seeds the proactive trim budget from it when evidence is not unknown, and
terminal metrics report only the stored resolution plus any limit the
provider stated during the turn. Metrics perform no discovery.
src/agent_loop.py and the regular runtime's legacy model_context probe are
unchanged. A conftest guard keeps tests that drive the compact runtime with
placeholder endpoints from performing real DNS/HTTP lookups.
Alexandre Teixeira