feat: v2.5.0 — Conditional-Request Taxonomy & Sequencers (§Phase 13 milestone 49)

.fusa-reqs.json

@@ -3351,6 +3351,78 @@
       "standard": "iso26262",
       "level": "ASIL-B",
       "asil": "ASIL-B"
+    },
+    {
+      "id": "REQ-SEQ-001",
+      "title": "message_timestamp-repurposing request_type decode/encode (mtv=0)",
+      "text": "rcp::sequencer::decode_request_type shall return SequencerErrc::timestamp_not_repurposed when mtv is true, shall return SequencerErrc::unknown_request_type when the top byte of message_timestamp is not one of the 8 defined opcodes, and shall otherwise recover the opcode and the remaining 7 parameter bytes exactly as produced by encode_request_type for the same inputs; rcp::sequencer::make_conditional_request shall always build an ACF_GBB AcfMessageInfo with mtv clear.",
+      "standard": "iso26262",
+      "level": "ASIL-B",
+      "asil": "ASIL-B"
+    },
+    {
+      "id": "REQ-SEQ-002",
+      "title": "Request categories and execution-priority ordering",
+      "text": "rcp::sequencer::category_of shall map the 3 cancellation opcodes to RequestCategory::Cancellation, each of the 5 conditional opcodes to its own category, and std::nullopt to RequestCategory::Standard; rcp::sequencer::select_next_due shall pick the candidate with the lowest priority_rank among due candidates and shall break ties within a category by lowest arrival_seq (FIFO), returning std::nullopt for an empty input.",
+      "standard": "iso26262",
+      "level": "ASIL-B",
+      "asil": "ASIL-B"
+    },
+    {
+      "id": "REQ-SEQ-003",
+      "title": "Compound/compound-wait optional-feature bundling",
+      "text": "rcp::sequencer::validate_feature_bundles shall return SequencerErrc::compound_bundle_incomplete whenever FeatureSet::compound or FeatureSet::compound_wait is set unless compound, compound_wait, clear_non_safestate, and sequencer_count >= kMinCompoundSequencers (4) are all simultaneously true, and shall accept every other combination of triggered/chained/timed/clear_single independently of compound support.",
+      "standard": "iso26262",
+      "level": "ASIL-B",
+      "asil": "ASIL-B"
+    },
+    {
+      "id": "REQ-SEQ-004",
+      "title": "Sequencer-state default value and finalization advance rule",
+      "text": "rcp::sequencer::SequencerTable::ensure_size shall fill newly added slots with kDefaultState (1), never the storage's own zero-initialization default, shall never shrink existing storage, and try_advance shall increment a sequencer only when its current value equals the supplied expected_start, leaving it unchanged (and reporting out_advanced=false, not an error) otherwise; both accessors shall return SequencerErrc::index_out_of_range for an out-of-bounds index.",
+      "standard": "iso26262",
+      "level": "ASIL-B",
+      "asil": "ASIL-B"
+    },
+    {
+      "id": "REQ-SEQ-005",
+      "title": "Cancellation kinds and shared cancellation semantics",
+      "text": "rcp::sequencer::RequestLedger::cancel_single shall cancel a Pending/Started request and cascade cancellation to every transitive chained successor, and shall return SequencerErrc::request_not_found for an unknown transaction or one that is UnderExecution/Finalized/already Canceled; cancel_all shall cancel every Pending/Started record (optionally skipping is_safety records when non_safestate_only is set) without disturbing any UnderExecution or Finalized record; a canceled request's outcome_of shall report SequencerErrc::request_canceled.",
+      "standard": "iso26262",
+      "level": "ASIL-B",
+      "asil": "ASIL-B"
+    },
+    {
+      "id": "REQ-SEQ-006",
+      "title": "Request lifecycle state machine: pending -> started -> under_execution -> finalized",
+      "text": "rcp::sequencer::RequestLedger shall only permit the single-step forward sequence Pending->Started->UnderExecution->Finalized, returning SequencerErrc::invalid_lifecycle_transition for any other requested transition and SequencerErrc::unknown_transaction for an untracked id; submit shall return SequencerErrc::transaction_num_collision for a transaction_num already tracked; finalize shall drive SequencerTable::try_advance for a Compound/CompoundWait record's sequencer_index/expected_start_state as its side effect.",
+      "standard": "iso26262",
+      "level": "ASIL-B",
+      "asil": "ASIL-B"
+    },
+    {
+      "id": "REQ-SEQ-007",
+      "title": "Chained-successor propagation on predecessor finalization",
+      "text": "rcp::sequencer::RequestLedger::finalize shall, for every record whose chained_predecessor equals the finalized transaction_num, cascade-cancel that successor iff rcp::sequencer::should_execute_chained(successor.cs, errored) is false, and shall leave every such successor untouched when the predecessor finalized with errored=false.",
+      "standard": "iso26262",
+      "level": "ASIL-B",
+      "asil": "ASIL-B"
+    },
+    {
+      "id": "REQ-SEQ-008",
+      "title": "The cs field's dual meaning (compound-wait vs. chained)",
+      "text": "rcp::sequencer::compound_wait_check_of shall map cs=true to CompoundWaitCheck::Immediate and cs=false to CompoundWaitCheck::AfterChangeOnly; rcp::sequencer::should_execute_chained shall return true whenever cs is true regardless of predecessor_errored, and shall return true iff predecessor_errored is false when cs is false.",
+      "standard": "iso26262",
+      "level": "ASIL-B",
+      "asil": "ASIL-B"
+    },
+    {
+      "id": "REQ-SEQ-009",
+      "title": "SequencerErrc is a distinct error category with non-empty, distinct messages",
+      "text": "Every rcp::sequencer::SequencerErrc value shall report rcp::sequencer::sequencer_category() as its category and shall have a non-empty diagnostic message distinct from every other SequencerErrc value's message.",
+      "standard": "iso26262",
+      "level": "ASIL-B",
+      "asil": "ASIL-B"
     }
   ]
 }

CMakeLists.txt

@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.21)
 
 project(cpp-rcp
-    VERSION 2.4.0
+    VERSION 2.5.0
     DESCRIPTION "Remote Control Protocol for automotive zonal architecture (C++)"
     HOMEPAGE_URL "https://github.com/SoundMatt/cpp-RCP"
     LANGUAGES CXX

ROADMAP.md

@@ -430,6 +430,48 @@ key off of. New coverage lives in `tests/test_i2c.cpp` (REQ-I2C-001..005),
 
 ### 49. Conditional-Request Taxonomy & Sequencers (v2.5.0)
 
+**Done (v2.5.0):** `rcp/sequencer.hpp` implements the taxonomy and state
+machine below entirely as a new decode/behavior layer over already-existing
+substrate — no change to `rcp/wire.hpp`'s ACF_GBB codec or
+`rcp/regmap.hpp`'s `sequencer_states` storage was needed. `decode_request_type`
+/`encode_request_type` implement the `mtv=0` message_timestamp-repurposing
+trick (`RequestTypeOpcode`'s 8 values: the 5 conditional kinds plus the 3
+cancellation kinds), gated so a genuinely timestamped ACF_GBB message
+(`mtv=1`) is rejected rather than misread; `make_conditional_request` builds
+the matching `AcfMessageInfo` for `rcp::wire::encode_acf_gbb` to carry
+unchanged. `RequestCategory`/`category_of`/`priority_rank`/`select_next_due`
+implement the seven-way execution-priority ordering (cancellation →
+triggered → timed → compound → compound-wait → chained → standard) with FIFO
+tie-break. `FeatureSet`/`validate_feature_bundles` enforce the compound
+bundle rule exactly as the roadmap states it: compound and compound-wait can
+only be claimed together, alongside clear-non-safestate cancellation and
+`sequencer_count >= kMinCompoundSequencers` (4) — triggered, chained, and
+timed remain independently flaggable. `SequencerTable` is the behavior layer
+over `regmap::RegisterMap::sequencer_states`: `kDefaultState` (1) fills newly
+grown slots (not the vector's own zero default), and `try_advance` advances a
+sequencer only while it still holds its expected start value, otherwise
+leaving it untouched without erroring. `RequestState`/`RequestRecord`/
+`RequestLedger` implement the forward-only pending → started →
+under_execution → finalized lifecycle (mirroring `rcp/lifecycle.hpp`'s own
+forward-only style), the three cancellation kinds' shared semantics
+(`cancel_single`/`cancel_all`, `REQUEST_CANCELED`/`REQUEST_NOT_FOUND` via
+`SequencerErrc`, already-executing requests left to finish, cascade-cancel
+into chained successors), and `finalize`'s two integration points: driving
+`SequencerTable::try_advance` for a Compound/CompoundWait record, and
+`propagate_chain_completion` evaluating each chained successor's `cs`-gated
+abort-on-predecessor-error rule via `should_execute_chained`.
+`compound_wait_check_of` and `should_execute_chained` implement the `cs`
+field's two independent meanings (compound-wait's immediate-vs-after-change
+check; chained's execute-regardless-vs-abort-on-error). This header
+deliberately does not run a scheduler thread — `select_next_due`'s output and
+`RequestLedger`'s transition methods are primitives for the embedding
+application to drive, same as every other endpoint header in this codebase.
+New coverage lives in `tests/test_sequencer.cpp` (REQ-SEQ-001..009), traced
+in `.fusa-reqs.json`. Full wire-level conformance (the safety-tagged `0x8x`
+variants and E2E CRC safe points this milestone's cancellation model already
+carries an `is_safety` field in anticipation of) remains a v2.6.0 concern per
+the Phase 13 introduction above.
+
 - Implement the `message_timestamp`-field-repurposing trick: when
   `mtv=0` on an ACF_GBB message, the first byte of the otherwise-unused
   64-bit timestamp slot becomes a `request_type` opcode, with the