A fresh same-session prior within the TTL is no longer sufficient to price
the text counterfactual warm: deriveBaselineWarmth now also requires the
static-prefix hash (system_sha8) to match. When opencode rotates the system
prompt / tool docs mid-session, the cacheable prefix changes, so a text-only
client would hit a new provider cache key too — pricing it warm against a
cold actual fabricated a huge phantom "loss" (the dashboard's 800%-worse
report). cr>0 still rescues a genuine warm read with no in-memory prior.
Wired through update(), replay(), and aggregateSessions via system_sha8.
Also surface losses honestly in the recent table (Saved/lost: negative
deltas in red instead of hidden as "—") and clarify headings as
billing-equivalent input tokens. Docs updated to match.
The savings accounting priced the text baseline as cold whenever pxpipe's own
image cache missed this turn (cr==0), fabricating a 1.25x create the text path
would never have paid and inflating reported savings ~2x. Decouple them: the
text prefix reads warm whenever a fresh same-session prior exists within the
300s TTL (wall-clock), unioned with an observed read (cr>0) for the post-restart
case. Centralised in deriveBaselineWarmth; used by all three call sites
(sessions, dashboard, fragments).
Empirical replay over ~/.pxpipe/events.jsonl (13,402 message rows): honest
headline 504.6M tokens saved vs the old cr-gated 1.05B; 1,409/12,305 fresh-prior
rows (11.4%) read warm despite a busted image cache. Dashboard now narrates the
busted-image case explicitly. Adds baseline/sessions/context-map regression
tests. Measurement only — no change to proxy behavior.
typecheck + 600 tests + build all green.
The Details panel divided the raw count_tokens baseline by sent tokens
(cache-blind), over-claiming "X% smaller" even when the cache-aware row
showed a net loss — the two panels could flatly contradict each other.
- dashboard.ts: feed baselineInputEff/actualInputEff/haveBaseline into
ContextMapData (same weighted pair the recent row uses); push after
the eff-tokens are computed so the breakdown matches.
- fragments.ts: headline divides weighted baseline by weighted actual,
says "bigger" on a net loss, with a clarifying sub-line; no savings
claim when the baseline probe did not resolve.
- +4 tests (context-map.test.ts) pinning headline direction to the row.
370 tests pass; typecheck + build clean.
Steven Chong