Keep fingerprint-only matching for authenticated visible histories that rebase spans, but require exact historical image positions for token and rewind reuse. Reproduce the old false hit with a synthetic checkpoint. Fix the live eviction oracle to include all competing slots. Four-slot Qwen and GLM vision/tool/eviction and concurrent-request tests pass. Follow-up to #765.
Upstream 81a7658 ("Preserve live vision context across server tool calls")
rewrote the live-continuation helpers this branch replaced with
slot_probe_reuse(): image markers carry request-local nonces and are
normalized for visible replay, image tokens are spliced into continuations
instead of being tokenized as text, and image appends are validated by
fingerprint and row count rather than by exact span equality. The merge
keeps the probe architecture and folds the new conditions into it, so slot
routing and the execution ladder still cannot disagree:
- The vision gate is fingerprint-prefix (new
ds4_session_vision_fingerprint_prefix_matches): historical images must
match by row count and fingerprint, positions may shift because
build_live_prompt_suffix() rebases them, and appended images are allowed.
An exact-state gate rejected valid appends, and a position-sensitive one
rejected replays that omit hidden reasoning.
- Every live tier materializes through build_live_prompt_suffix(), so new
images are spliced into the continuation and a failed rebase is a safe
miss rather than a malformed prompt.
- responses-visible and thinking-visible compare in visible_prompt_key
space, so a replay with fresh marker nonces still binds while a changed or
shifted image does not.
- Tool-output-only continuations keep upstream's contract: if the selected
live tier cannot be materialized, the request is answered with 409
(live_continuation_unavailable) instead of being generated from a
context-free prompt built from tool outputs alone.
- Single-session mode refreshes the slot's rendered-text cache like the
batched worker does, so the memory-text tier is probe-authoritative on
both worker paths; the redundant ladder fallback and the four superseded
upstream helpers are removed.
Tests: test_slot_probe_vision_tiers covers image appends, pixel mismatches
and marker-nonce visible replay at the probe/routing level;
test_live_continuation_contract pins the 409 predicate;
tests/test_session_state.c gains fingerprint-prefix cases; and the new live
suite tests/test_server_vision_live_state.py checks slot routing, eviction
victims and the tool-result-only 409 against a real vision model.
Verified on DeepSeek V4 Flash Vision Experimental (M5 Max): ./ds4_test
--server, ds4_agent_test, test-session-state, live test_server_vision_cache.py
(1- and 4-session), test_server_story.py, test_server_batching.py and the new
vision live-state suite all pass.
Salvatore Sanfilippo
Mikhail Korobov