Three operator decisions change v1's premises, so the design is now two tiers
with separate flags:
Tier A (THERMOGRAPH_EVENTS) is v1 unchanged -- anonymous hourly aggregates, no
identifier, nothing stored on the device, no consent needed, runs for everyone.
It stays the primary signal precisely so a poor consent rate cannot take the
numbers down with it, and so Tier B's rates can be calibrated against it to
measure the consent bias rather than ignoring it.
Tier B (THERMOGRAPH_EVENT_SESSIONS) adds an ephemeral per-tab id -- 16 random
bytes in sessionStorage, rotating on a 30-minute idle and a 2-hour absolute cap,
capped at 200 events, never linked to another session, device, or to the account
(api_event does not read the auth cookie and there is no user column). Rows land
in a 30-day hypertable with minute-granularity timestamps and an in-session
sequence number instead of precise clock times. Storing an identifier engages
ePrivacy Art. 5(3) and analytics is not strictly necessary, so it is gated on
opt-in consent: an equal-weight banner that mints nothing before "Allow",
one-click withdrawal in every footer that drops the live id immediately, and
GPC/DNT treated as a refusal already given.
THERMOGRAPH_SEARCH_MISS captures zero-result search text server-side in
api_suggest only -- normalised, rejected outright on any personal-data smell,
stored as a per-day count, and pruned below a three-person floor after a week.
The privacy page is rewritten rather than deferred: "no per-visitor identifier"
becomes false the moment Tier B ships. Tests assert the load-bearing promises so
the copy and the code cannot drift apart silently.
Raw-IP truncation is NOT implemented here (the logging pipeline owns it) but
UI-EVENTS.md states what the app side must do, and records that Caddy's default
JSON log already stores full request URIs -- so every search query is in Loki
with the client IP today, which the search-miss mitigations depend on fixing.
UI-EVENTS.md carries the v1-to-v2 diff, the consent reasoning including why
legitimate interest is not available, and an explicit argument that the session
identifier is the wrong trade at this traffic volume.
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