Contract reference (generated)

Machine-generated snapshot of the FFI / pipe contract from the values defined in the fmf-contract crate. The prose canonical source for semantics and the safety contract is Architecture; for Rust API details see rustdoc (/doc/fmf_contract/). Numbers are the actual offset_of! / size_of! values.

Versions and pipe name

Item	Value
`ABI_VERSION`	2
`PROTOCOL_VERSION`	2
`PIPE_NAME`	`\\.\pipe\fmf-engine-v2`
`PIPE_NAME_SHORT`	`fmf-engine-v2`
`SERVICE_NAME`	`fmf-engine`

Status codes (frame header status / FFI return values. append-only)

Name	Value
`OK`	0
`INVALID_ARG`	1
`STALE`	2
`NOT_ADMIN`	3
`VOLUME`	4
`QUERY_SYNTAX`	5
`IO`	6
`LOCKED`	7
`PANIC`	99

Pipe opcodes (event pushes reuse 1..=6 as the kind)

Name	Value
`HELLO`	1
`SUBSCRIBE`	2
`UNSUBSCRIBE`	3
`LIST_VOLUMES`	4
`INDEX_START`	5
`INDEX_STATUS`	6
`QUERY`	7
`RESULT_PAGE`	8
`RESULT_FREE`	9
`STATS`	10
`FLUSH_RESERVED`	11
`SERVICE_INFO`	12

Event kinds (FFI `FmfEvent.kind` = pipe event-push opcode)

Kind	Value
`Progress`	1
`VolumeReady`	2
`IndexChanged`	3
`RescanStarted`	4
`VolumeFailed`	5
`EngineError`	6

Limits (protocol facts. not tunable)

Constant	Value
`MAX_PAYLOAD_LEN`	16777216
`MAX_RESULTS_PER_CONN`	64
`EVENT_QUEUE_CAP`	256
`PAGE_ROWS`	64

POD layouts (`#[repr(C)]`, actual `offset_of!` values)

`FrameHeader` (16 B)

Field	offset
`len`	0
`opcode`	4
`flags`	6
`request_id`	8
`status`	12

`FmfRow` (48 B)

Field	offset
`entry_ref`	0
`frn`	8
`size`	16
`mtime`	24
`name_off`	32
`parent_path_off`	36
`flags`	40
`name_len`	44
`parent_path_len`	46

`FmfQueryOptions` (20 B)

Field	offset
`sort`	0
`desc`	4
`case_mode`	8
`include_hidden_system`	12
`regex_mode`	16

`FmfPage` (32 B)

Field	offset
`row_count`	0
`rows`	8
`blob`	16
`blob_len`	24

`FmfEvent` (32 B)

Field	offset
`kind`	0
`entries`	8
`volume`	16

`FmfVolumeStatus` (32 B)

Field	offset
`label`	0
`state`	16
`entries`	24

`FmfBlob` (16 B)

Field	offset
`data`	0
`len`	8

Degradation counter names (`snake_case` keys of the stats JSON. append-only)

stat_fetch_failures
usn_batches_truncated
snapshot_load_failures
snapshot_save_failures
deferred_names_unresolved
corrupt_mft_records
journal_rescans
scan_pipeline_fallbacks
offset_table_rebuild_fallbacks
lazy_perm_rebuild_fallbacks
compaction_aborts
pipe_malformed_frames
pipe_events_dropped
pipe_connections_rejected
deferred_name_cache_overflow
deferred_name_read_failures
pipe_results_evicted
trace_serialize_failures
walk_read_errors
walk_depth_truncated

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