{
  "file": "C:/Users/decid/Documents/projects/spt-core/.worktrees/iolog-277/crates/spt-store/src/iolog.rs",
  "status": "Source and regressions implemented; no validation or formatting commands run, as assigned.",
  "design": [
    "last_seq_at reads bytes, discards the fragment through its first LF before lossy decoding, returns the maximum complete-row prefix in the window, and falls back to whole-file bytes if no complete row remains (including a giant LF-terminated row).",
    "Append performs one whole-file byte read under the existing exclusive stable lock. Its single integrity scan collects physical-line count, global maximum, and any adjacent non-increase (<=), including duplicates and internal resets. Healthy appends do not rewrite history.",
    "Damaged logs retain file-order history using normal last-N retention, then renumber retained keyed rows above the pre-repair global maximum without changing JSON payload bytes. Oversized history retains the newest 1000 rows before repair. Unkeyed corrupt lines remain unchanged and count toward retention.",
    "All repair increments and the appended sequence use checked_add. Repair and new-row serialization are preflighted before any mutation, so exhaustion refuses without modifying history.",
    "Trim uses physical-line positions and retains the newest 1000 only above 1250. It reuses the append scan's bytes rather than rereading the file; ordinary post-append trim remains best-effort.",
    "read_after_at now returns public IoLogRead { rows, head }. Head is the global prefix maximum of the same shared-lock byte snapshot, including prefixes with malformed JSON, regardless of after/limit. Scanning continues after the output cap without unnecessary JSON parses. All local unit callers migrated.",
    "Added requirement-proximate impl/unit tags for REQ-HAZARD-IOLOG-SEQ-MONOTONIC and repair/retention REQ-IO-EVENT-ADAPTER-LOG coverage."
  ],
  "scan_cost": "Each healthy append reads and scans O(log bytes), bounded normally by 1250 payload-capped rows, with JSON escaping included in actual disk size. Memory holds that byte snapshot; repair additionally allocates the retained suffix rewrite. Legacy oversized logs require their full scan until repair/retention succeeds. No sidecar/cache, repeated healthy rewrite, or redundant full read was introduced.",
  "new_tests": [
    "a_tail_window_inside_three_byte_utf8_never_resets_the_seq",
    "a_tail_without_a_complete_row_falls_back_to_the_whole_file",
    "reset_blocks_repair_above_the_max_without_changing_payload_bytes",
    "equal_adjacent_seqs_are_repaired",
    "an_internal_reset_is_repaired_even_when_last_exceeds_first",
    "repair_uses_the_global_max_even_when_it_is_outside_the_tail",
    "trimming_1251_reset_rows_keeps_the_newest_1000_by_position",
    "oversized_repair_retains_bounded_newest_history",
    "sequence_exhaustion_refuses_without_modifying_history",
    "healthy_sequence_gaps_do_not_trigger_repair_or_retention",
    "a_poll_reports_the_true_snapshot_head_independent_of_selected_rows"
  ],
  "retained_tests": [
    "appends_assign_monotonic_seqs_from_one",
    "the_log_trims_oldest_first_at_the_bound (including last_seq_at never rewinding across trim)",
    "All other existing module tests, migrated to IoLogRead.rows."
  ],
  "mutation_points": [
    "Restore last_seq_at read_to_string/InvalidData -> 0: the deterministic UTF-8 test directly asserts last_seq_at == 32 before append == 33, so the independent append integrity scan cannot mask the regression.",
    "Replace tail max with last prefix: reset_blocks_repair_above_the_max_without_changing_payload_bytes expects last_seq_at == 203 for [201,202,203,1,2,3].",
    "Replace adjacent <= with <: equal_adjacent_seqs_are_repaired fails.",
    "Use last < first as the integrity check: an_internal_reset_is_repaired_even_when_last_exceeds_first fails on [1,2,1,3].",
    "Use tail-only or retained-suffix-only maximum: repair_uses_the_global_max_even_when_it_is_outside_the_tail and oversized_repair_retains_bounded_newest_history fail respectively.",
    "Reserialize or reorder retained payloads: exact byte comparisons in repair regressions fail.",
    "Restore seq-distance counting/value-filter trimming: healthy_sequence_gaps_do_not_trigger_repair_or_retention and trimming_1251_reset_rows_keeps_the_newest_1000_by_position fail. The latter includes a value-filter negative control that loses 999 newest rows.",
    "Saturate/wrap sequences or commit repair before checking new-row capacity: sequence_exhaustion_refuses_without_modifying_history fails.",
    "Stop scanning at limit, derive head from selected rows/after, or ignore malformed-JSON prefixes: a_poll_reports_the_true_snapshot_head_independent_of_selected_rows fails."
  ],
  "jit_semantics": [
    "JIT B/C's suggested first/last comparison cannot establish monotonicity. The assignment's stronger requirement needs the full adjacent-prefix scan on every append absent persistent state; implemented explicitly.",
    "The JIT mutation claim that restoring read_to_string necessarily makes append mint 1 no longer holds after the independent full integrity scan. The direct last_seq_at mechanism assertion intentionally catches that mutation; parent should describe this distinction in mutation evidence.",
    "No runtime verification or mutation runs performed; parent gate owns them."
  ]
}