#1553 - gate history + currentQuery egress on /ai/ask at send-time

[juanresendiz813]

Fixes #1553.

Problem

The /ai/ask egress gate (#1554) stripped only the cellsetDigest. history and currentQuery still reached the LLM ungated, so cell-derived data leaked even at schema-only. Killer case: a turn-1 aggregated insight is replayed by the client at turn-2 schema-only — the assistant turn carrying model-emitted figures egresses regardless of the current posture. History is client-supplied and untrusted every turn, so the only enforceable control is at send-time.

Fix (Option B — "drop, not redact", send-time re-gate)

When the active posture forbids aggregated egress (!egressPermitsCellData(), fail-closed on a null/unwired guard), at the request-building seam — before the NlAskRequest is constructed, so both providers are covered in one place:

• Drop assistant-role history turns, keep the user's own turns. Assistant turns replay emit_insight/emit_email_draft figures.
• Strip currentQuery filter members — clear filters[].members while keeping the query structure (measures/rows/columns/cube + filter dimension/hierarchy/level refs). The model still sees the query shape, not which members were picked.

Applied in both askInternal (the /ai/ask seam) and the askChained preamble, mirroring the existing cellsetDigest strip and its fail-closed semantics. Both re-gates are copy-not-mutate: history is filtered into a new list; currentQuery is redacted on a mapper round-trip copy, so the caller-owned objects are never touched.

The agentic toolTranscript needed no change — its egress-withheld path (resultDigest == null) already holds, and under schema-only the chained loop stops before it ever executes/digests, so no data-bearing tool turn is produced. Confirmed with a test.

Tests

Added to AiAskServiceTest, mirroring the #1554 egress/digest-strip tests:

• schema-only: assistant history turns dropped, user turns kept; currentQuery.filters[].members cleared, structure retained.
• aggregated: history + currentQuery pass through untouched.
• Fail-closed: null/unwired guard drops + strips.
• No mutation of the caller's original history/currentQuery.
• toolTranscript withheld-path stays withheld under schema-only.

One pre-existing test (passesQuestionAndHistoryToProviderUnchanged) asserted full-history passthrough with no guard wired; it now wires an AGGREGATED posture to keep asserting the plumbing forwards history intact (the fail-closed drop is covered by the dedicated tests).

mvn -o -pl saiku-core/saiku-service test -Dtest=AiAskServiceTest,OssieAiAskServiceTest,AiPolicyGuardTest,ToolTurnTest → 103 tests, 0 failures. spotless:apply clean.