new learnigns

README.md

@@ -45,6 +45,8 @@ To start the current emulator harness:
 .\.venv\Scripts\python.exe h8536_emulator_rx_probe.py --preset connect-lcd
 .\.venv\Scripts\python.exe scripts\bench_connect_lcd_sequence.py --port COM5 --relay-port COM6 --prompt-screen
 .\.venv\Scripts\python.exe scripts\serial_ack_probe.py --ack-frame "05 00 40 00 00 1F"
+.\.venv\Scripts\python.exe scripts\serial_scenario.py scenarios\ack-race-000-001.json --log captures\ack-race-000-001.txt --result-json captures\ack-race-000-001-result.json
+.\.venv\Scripts\python.exe scripts\serial_scenario.py scenarios\table-sweep-ack-000-07f.json --log captures\table-sweep-ack-000-07f.txt --result-json captures\table-sweep-ack-000-07f-result.json
 .\.venv\Scripts\python.exe h8536_emulator_bench_replay.py captures\bench-connect-lcd-sequence-20260525-214411.txt --assert-bench-parity
 ```
 
@@ -92,6 +94,8 @@ The real-device bench helper uses `pyserial`; install repo dependencies with `.\
 - Includes an RX command probe that boots until SCI1 RXI is serviceable, injects host six-byte frames through RDR/RDRF, can optionally schedule 38400 8N1 byte arrivals at real UART spacing, listens for device TX frames, and reports serial latch/table/LCD-buffer and emulated-LCD effects.
 - Includes a bench helper for replaying the emulator-derived CONNECT LCD frame sequence against the real device through COM5, with optional COM6 relay power cycling and timestamped capture logs.
 - Includes a bench ACK probe that reproduces the `01 00 00...` -> `01 00 01...` visible retry burst, waits for `07 80 40 20 90 2D`, then sends a candidate command-5 ACK and reports whether the target keeps repeating.
+- Includes a checksum-resynchronizing bench receiver that scans RX byte streams for valid six-byte frames, avoids common shifted-heartbeat false locks, and can fall back to the old fixed six-byte slicer with `--sync fixed`.
+- Includes a JSON scenario bench runner for repeatable multi-step serial tests, including low-latency ACK-aware command-1 probes that can send the current command-5 ACK candidate immediately after the retry frame appears, with explicit max-ACK/max-target guardrails.
 - Includes a bench-log replay harness that feeds recorded host TX frames back into the ROM emulator with bench-style UART byte timing by default and asserts parity against the real device's observed response/LCD state.
 
 Current serial observations:
@@ -227,6 +231,9 @@ python h8536_emulator_rx_probe.py --help
 - `h8536_emulator_rx_probe.py --uart-timing --uart-baud 38400 "04 00 00 80 00"`: inject all six host bytes with 8N1 wire spacing of about 260 us per byte, letting RXI/TXI/timers interleave; if the ROM has not cleared `RDRF` before the next byte, the SCI model raises `ORER`.
 - `h8536_emulator_rx_probe.py --preset connect-lcd`: replay the current CONNECT LCD activation candidates.
 - `scripts\serial_table_dump.py --port COM5 --relay-port COM6 --start 0x000 --count 0x200 --log captures\table-read.txt`: read-only command-1 sweep of the firmware-exposed serial table state for EEPROM/shadow inference.
+- `scripts\serial_scenario.py scenarios\ack-race-000-001.json --log captures\ack-race-000-001.txt --result-json captures\ack-race-000-001-result.json`: run the focused `0x000 -> 0x001` retry probe with immediate reactive ACK and a 2 ms poll interval, to test whether command 5 can arrive before the second `07 80 40 20 90 2D` retry.
+- `scripts\serial_scenario.py scenarios\early-ack-000-001.json --log captures\early-ack-000-001.txt --result-json captures\early-ack-000-001-result.json`: send the same command-1 pair, then send command-5 ACK immediately without waiting for the retry frame.
+- `scripts\serial_scenario.py scenarios\table-sweep-ack-000-07f.json --log captures\table-sweep-ack-000-07f.txt --result-json captures\table-sweep-ack-000-07f-result.json`: run a repeatable bench scenario that sweeps selectors `0x000-0x07F` and sends `05 00 40 00 00 1F` only after `07 80 40 20 90 2D` appears. The checked-in scenario stops if it reaches 8 ACKs or 32 target hits. Use `--sync fixed` only when comparing against the old non-resyncing receiver.
 - `scripts\bench_connect_lcd_sequence.py --port COM5 --relay-port COM6 --prompt-screen`: power-cycle the bench device, wait for heartbeat readiness, send `04 00 00 40 00 1E`, `04 00 00 80 00 DE`, `04 00 00 C0 00 9E`, log RX/TX, and prompt for observed LCD text.
 - `h8536_emulator_bench_replay.py captures\bench-connect-lcd-sequence-20260525-214411.txt --assert-bench-parity`: replay a real bench log into the emulator using timed UART RX by default and intentionally fail while any response/LCD state still diverges from the bench-observed `CONNECT NOT ACT` plus `07 80 C0 60 20 5D` path. Pass `--polite-rx` for the old wait-until-consumed injection mode.
 - Current status: boots from `H'1000`, initializes SCI1, models the traced X24164 EEPROM bus on P9, captures P9 byte candidates, can optionally fast-path known P9 EEPROM routines, schedules FRT1/FRT2 OCIA from timer registers and `--clock-hz`, captures the ROM-driven LCD line ` CONNECT:NOT ACT`, and emits the observed heartbeat frame `00 00 00 00 80 DA`.
@@ -256,6 +263,7 @@ python h8536_emulator_rx_probe.py --help
 - `h8536/serial_pseudocode.py`: focused RX/TX protocol pseudocode generation from reconstruction metadata.
 - `h8536/protocol_trace.py`: raw six-byte protocol frame decoder/checksum validator.
 - `h8536/protocol_capture.py`: timestamped serial capture parser, frame recombiner, and cadence/gate-session analyzer.
+- `h8536/serial_scenario.py`: JSON-driven bench scenario engine shared by real-device serial scripts.
 - `h8536/serial_gate.py`: autonomous TX gate/queue state-machine reconstruction.
 - `h8536/report_source_trace.py`: direct `loc_3E54` report enqueue source tracer.
 - `h8536/table_xrefs.py`: table/index xrefs and LCD correlation report generation.
@@ -274,3 +282,4 @@ python h8536_emulator_rx_probe.py --help
 - `h8536_emulator.py`, `h8536_emulator_probe.py`, `h8536_emulator_rx_probe.py`, `h8536_emulator_bench_replay.py`: emulator CLI wrappers.
 - `scripts/bench_connect_lcd_sequence.py`: real-device COM5/COM6 bench runner for the CONNECT LCD sequence.
 - `scripts/serial_table_dump.py`: read-only COM5/COM6 command-1 table sweep for inferring live EEPROM-backed parameter state.
+- `scripts/serial_scenario.py`: JSON-driven COM5/COM6 bench scenario runner for chained probes, waits, read sweeps, and ACK-on-target experiments.

build/rom_serial_pseudocode.c

@@ -113,26 +113,45 @@ extern volatile u8 MEM8[0x10000];
  * - byte4: value_lo (medium) - candidate low byte of a word value
  * - byte5: checksum (high) - 0x5A-seeded XOR of bytes 0..4
  * dispatch: command_low3 = RX_FRAME(0) & 0x07; observed H'00, H'01, H'02, H'04, H'05, H'06, H'07
+ * dispatcher split: FAA2 == 0 accepts initial/idle commands H'00, H'01, H'02, H'07; FAA2 != 0 accepts continuation commands H'04, H'05, H'06, H'07
+ * dispatcher caveat: Initial dispatch follows checksum validation and RX error handling. Command 1 is only on the initial/idle path and is also gated by F861.bit7 == 0.
  * dispatch evidence: H'BC08, H'BC0C, H'BC20, H'BC22, H'BC24, H'BC26, H'BC29, H'BC2B, H'BC2E, H'BC30, H'BC45, H'BC47, H'BC4A, H'BC4C, H'BC4F, H'BC51, H'BC54, H'BC56
  * index decoder: RX[1:2] -> logical index via loc_622B (medium)
  * command candidates:
  * - H'00 set_value_acked: candidate write of RX[3:4] into primary/current tables, followed by a response; handler H'BC69; responses response_at_BCCD
- * - H'01 read_value: candidate read from the primary table, followed by a response carrying the value; handler H'BCD7; responses response_at_BCFA
+ *   availability: valid checksum/no RX physical error && FAA2 == 0
+ * - H'01 read_value: initial/idle-path primary table read only, followed by an odd response staging sequence; handler H'BCD7; responses response_at_BCFA
+ *   availability: valid checksum/no RX physical error && FAA2 == 0 && F861.bit7 == 0
+ *   note: Only accepted on the initial/idle dispatcher path: valid checksum/no RX error, FAA2 == 0, and F861.bit7 == 0.
+ *   note: BCD7 stages F850=0x04, writes F851 from F861 and then overwrites F851 from F862.
+ *   note: BCD7 reads the primary table word at E000 + 2*selector; F854 receives the low byte and F853 receives the high byte.
+ *   note: F852 is not freshly written in the BCD7 handler, so do not describe the response as a fixed 04 00 QQ hi lo frame.
  * - H'02 clear_or_abort: candidate clear/abort path with no immediate response builder; handler H'BD04; responses none
+ *   availability: valid checksum/no RX physical error && FAA2 == 0
  * - H'04 set_value_no_immediate_reply: candidate write/update path that stores a value without an immediate serial response; handler H'BD0E; responses none
- * - H'05 ack_or_clear_pending: candidate pending/event acknowledgement path; handler H'BD80; responses none
+ *   availability: valid checksum/no RX physical error && FAA2 != 0
+ * - H'05 ack_or_clear_pending: continuation-only conditional acknowledgement/session clear path; handler H'BD80; responses none
+ *   availability: valid checksum/no RX physical error && FAA2 != 0
+ *   note: Only accepted on the continuation dispatcher path when FAA2 != 0.
+ *   note: For selector 0x0040, frame 05 00 40 00 00 1F performs no response staging.
+ *   note: The handler clears FAA3/FAA2; F9B5 advances only when FAA2.bit3 was set from a queued report.
+ *   note: If FAA2 == 0, command 5 falls through the initial dispatcher instead of doing acknowledgement work.
  * - H'06 set_secondary_value: candidate secondary-table value write path; handler H'BDDB; responses none
- * - H'07 retransmit_or_error_reply: candidate retransmit/NAK-style path; error handling also builds command 0x07 responses; handler H'BE05; responses response_at_BE22
+ *   availability: valid checksum/no RX physical error && FAA2 != 0
+ * - H'07 retransmit_or_error_reply: candidate retransmit path; retry/error handling also builds a command 0x07 RX-payload echo; handler H'BE05; responses response_at_BE22
+ *   availability: valid checksum/no RX physical error && FAA2 == 0 OR valid checksum/no RX physical error && FAA2 != 0
+ *   note: loc_BE4D is a retry/error echo path: F850=0x07 and F861-F864 are copied into F851-F854 before loc_BA26.
+ *   note: Observed frame 07 80 40 20 90 2D means RX bytes F861-F864 were 80 40 20 90; it is not a table value.
  * command effects:
  * - H'00 set_value_acked: Candidate acknowledged set: writes value bytes to primary/current tables, flags the index, and stages an echo-style response.
  *   effect: table_write_candidate; target primary_value_table_candidate; source RX[3:4] value bytes, with an observed 0x80 fallback when decoded index is zero; table H'E000
  *   effect: table_write_candidate; target current_value_table_candidate; source same candidate value written to the primary table; table H'E800
  *   effect: flag_update_candidate; target per_index_flag_table_candidate; set bit 7; table H'EC00
  *   evidence: H'BC08, H'BC0C, H'BC20, H'BC22, H'BCB0, H'BCB9, H'BCC1, H'BCC9, H'BCB5, H'BCBD, H'BCC5, H'BCCD
- * - H'01 read_value: Candidate read: reads the primary table and stages a value response.
+ * - H'01 read_value: Initial/idle candidate read: reads the primary table and stages an odd value response with F852 possibly stale.
  *   effect: table_read_candidate; target primary_value_table_candidate; table H'E000
  *   effect: response_staging_candidate; stage F850-F854 and call loc_BA26
- *   evidence: H'BC08, H'BC0C, H'BC24, H'BC26, H'BCB0, H'BCB9, H'BCC1, H'BCC9, H'BCD7, H'BCE0, H'BCE8, H'BCF0, H'BCF6, H'BCB5, H'BCBD, H'BCC5, H'BCDC, H'BCE4, H'BCFA
+ *   evidence: H'BC08, H'BC0C, H'BC24, H'BC26, H'BCD7, H'BCE0, H'BCE8, H'BCF0, H'BCF6, H'BCDC, H'BCE4, H'BCFA
  * - H'02 clear_or_abort: Candidate clear/abort: clears serial session state without an observed immediate response.
  *   effect: state_clear_candidate; target serial_session_flags_candidate; clear bit 7; state H'FAA2
  *   evidence: H'BC08, H'BC0C, H'BC29, H'BC2B
@@ -140,15 +159,16 @@ extern volatile u8 MEM8[0x10000];
  *   effect: table_write_candidate; target primary_value_table_candidate; source RX[3:4] value bytes, with an observed 0x80 fallback when decoded index is zero; table H'E000
  *   effect: flag_update_candidate; target per_index_flag_table_candidate; set bit 7; table H'EC00
  *   evidence: H'BC08, H'BC0C, H'BC45, H'BC47
- * - H'05 ack_or_clear_pending: Candidate acknowledgement/clear: updates pending/event state without an observed immediate response.
+ * - H'05 ack_or_clear_pending: Continuation-only ACK/session clear: clears FAA3/FAA2 and only advances F9B5 when queued-report FAA2.bit3 was set; selector 0x0040 has no response.
- *   effect: pending_acknowledgement_candidate; target selected event/pending state; clear selected pending flags and then clear serial session state
+ *   effect: conditional_ack_session_clear_candidate; target selected event/pending state; when FAA2 != 0, clear FAA3/FAA2; advance F9B5 only if FAA2.bit3 was set from queued-report state; selector 0x0040 stages no response; selector H'0040 has no response
  *   evidence: H'BC08, H'BC0C, H'BC4A, H'BC4C
  * - H'06 set_secondary_value: Candidate secondary set: writes value bytes to the secondary table and flags the index.
  *   effect: table_write_candidate; target secondary_value_table_candidate; source RX[3:4] value bytes; table H'E400
  *   effect: flag_update_candidate; target per_index_flag_table_candidate; set bit 6; table H'EC00
  *   evidence: H'BC08, H'BC0C, H'BC4F, H'BC51
- * - H'07 retransmit_or_error_reply: Candidate retransmit/error reply: reuses prior TX bytes or builds an explicit 0x07 retry/error response.
+ * - H'07 retransmit_or_error_reply: Candidate retransmit/error reply: reuses prior TX bytes or copies RX payload bytes behind an explicit 0x07 retry/error echo.
  *   effect: retransmit_candidate; target TX staging bytes H'F850-H'F854 before loc_BA26; source previous TX frame bytes H'F858-H'F85C
+ *   effect: retry_error_echo_candidate; target F850=0x07, F851-F854=F861-F864 before loc_BA26; source RX payload bytes F861-F864; 07 80 40 20 90 2D echoes RX payload 80 40 20 90; it is not a table value
  *   effect: response_staging_candidate; stage F850-F854 and call loc_BA26
  *   evidence: H'BC08, H'BC0C, H'BC2E, H'BC30, H'BC54, H'BC56, H'BE09, H'BE11, H'BE19, H'BE22
  * response schemas:
@@ -156,8 +176,11 @@ extern volatile u8 MEM8[0x10000];
  *   evidence: H'BB1C, H'BB2B, H'BB20, H'BB3F, H'BB39
  * - response_at_BCCD: byte0=0x04; byte1=rx[1]; byte2=rx[2]; byte3=rx[3]; byte4=rx[4]
  *   evidence: H'BCB0, H'BCB9, H'BCC1, H'BCC9
- * - response_at_BCFA: byte0=0x04; byte1=rx[2]; byte2=rx[2]; byte3=primary_value_table_candidate; byte4=primary_value_table_candidate
+ * - response_at_BCFA: byte0=0x04; byte1=rx[2]; byte2=stale/unchanged; byte3=primary_value_table_candidate; byte4=primary_value_table_candidate
- *   evidence: H'BCD7, H'BCE8, H'BCC1, H'BCF6, H'BCF0
+ *   note: Command 1 BCD7 staging is odd: F850=0x04; F851 is written from F861 then overwritten by F862.
+ *   note: The primary table word is read from E000 + 2*selector; F854/F853 receive low/high value bytes.
+ *   note: F852 may be stale or unchanged in this handler; avoid a fixed 04 00 QQ hi lo response shape.
+ *   evidence: H'BCD7, H'BCE8, H'BCF6, H'BCF0
  * - response_at_BE22: byte0=tx[0]; byte1=tx[1]; byte2=tx[2]; byte3=tx[3]; byte4=tx[4]
  *   evidence: H'BE09, H'BE11, H'BE19
  * - ... 1 more candidate response schemas
@@ -186,7 +209,9 @@ extern volatile u8 MEM8[0x10000];
  * - ... 7 more state-variable candidates
  * retry/error model candidate:
  * - checksum path: 0x5A-seeded XOR over RX[0..4] differs from RX[5] -> loc_BE29
- * - retry path: counter H'FAA6, threshold 2; Candidate retry path clears/consults serial flags, increments FAA6, compares it with 2, and when still below the apparent limit stages a command 0x07 response.
+ * - retry path: counter H'FAA6, threshold 2; Candidate retry path clears/consults serial flags, increments FAA6, compares it with 2, and when still below the apparent limit enters loc_BE4D to stage a command 0x07 retry/error echo of RX payload bytes F861-F864.
+ *   echo path: loc_BE4D: F850=0x07; F851-F854=F861-F864
+ *   echo caveat: 07 80 40 20 90 2D echoes RX payload 80 40 20 90 and is not a table value.
  * - command 0x07 path: Candidate retransmit/explicit command 0x07 path either copies previous TX frame bytes back to F850-F854 or stages an observed 0x07 response before loc_BA26.
  * - evidence: H'BBD8, H'BBDC, H'BBE0, H'BBE4, H'BBE8, H'BBEC, H'BBF0, H'BE4D, H'BE56, H'BE5E, H'BE66, H'BE52, H'BE5A, H'BE62, H'BE6A, H'BE29, H'BE2D, H'BE33, H'BE37, H'BE43, H'BE47, H'BE05, H'BE0D, H'BE15, H'BE09, H'BE11, H'BE19, H'BE22
  * gate/queue state machine candidate:
@@ -201,7 +226,7 @@ extern volatile u8 MEM8[0x10000];
  * - session_timeout_clears_gate_and_queue: When F9C5 is clear, loc_3FEF clears F9B5/F9B0 and clears FAA5.bit7; when nonzero, it sets FAA5.bit7.
  * - idle_heartbeat_gate_initial_delay_loaded: Startup/init loads F9C4 with H'14 before the first idle/default report can be queued.
  * - idle_heartbeat_gate_post_send_delay_loaded: loc_BA26 reloads F9C4 with H'07 after each send, matching the observed heartbeat spacing.
- * - host_ack_can_advance_queue: Commands 0x05/0x06 are modeled as acknowledgement paths that can clear pending state or advance F9B5.; commands H'05, H'06
+ * - host_ack_can_advance_queue: Command 0x05 is a continuation-only ACK/session clear path: it clears FAA3/FAA2 and advances F9B5 only when queued-report FAA2.bit3 was set. Selector 0x0040 has no response; if FAA2 == 0 the command falls through instead of doing ACK work.; commands H'05
  * - caveat: Many panel controls may require host/session traffic before reporting. Observed autonomous call/camera-power indexes are runtime/capture overlays, not ROM constants.
  * - evidence: H'3FD3, H'3FD7, H'3FD9, H'3FDD, H'3FDF, H'3FE3, H'3FE5, H'3FE9, H'3FEB, H'3FEF, H'3FF3, H'3FF5, H'3FF9, H'3FFD, H'4001, H'4003, H'4005, H'4007, H'4046, H'404A, H'404C, H'4050, H'4052, H'4056, H'4058, H'4059, H'405D, H'405F, H'4063, H'4065, H'4067, H'406C, H'4070, H'BAF2, H'BAF6, H'BAF8, H'BAFC, H'BAFE, H'BB00, H'BB04, H'BB06, H'BB08, H'BB0C, H'BB0E, H'BB11, H'BB13, H'BB15, H'BB17, H'BB19, H'BB1C, H'BB20, H'BB24, H'BB26, H'BB29, H'BB2B, H'BB2F, H'BB33, H'BB35, H'BB39, H'BB3D, H'BB3F, H'BB43, H'BE9E, H'BEA2, H'BEA5, H'BEA9, H'BEAD, H'BEAF, H'BEB3, H'BEB5, H'BEB9, H'BEBB, H'BEBF, H'BEC1, H'BEC5, H'BECB, H'BECF, H'BED1, H'BED5
  * TX/autonomous report model candidate:
@@ -338,33 +363,70 @@ void sci1_process_candidate_protocol_command(void)
     u16 logical_index = sci1_rx_candidate_logical_index();
     u16 value = sci1_rx_candidate_value();
 
+    bool session_active = MEM8[0xFAA2u] != 0u;
+
+    if (!session_active) {
+        /* Initial/idle dispatcher: valid checksum/no RX error, FAA2 == 0. */
+        switch (command) {
+        case 0x00u:
+            /* set_value_acked: candidate write of RX[3:4] into primary/current tables, followed by a response
+             * availability: valid checksum/no RX physical error && FAA2 == 0
+             * candidate effect: table_write_candidate; target primary_value_table_candidate; source RX[3:4] value bytes, with an observed 0x80 fallback when decoded index is zero; table H'E000
+             * candidate effect: table_write_candidate; target current_value_table_candidate; source same candidate value written to the primary table; table H'E800
+             * candidate effect: flag_update_candidate; target per_index_flag_table_candidate; set bit 7; table H'EC00
+             * evidence: H'BC08, H'BC0C, H'BC20, H'BC22, H'BCB0, H'BCB9, H'BCC1, H'BCC9, H'BCB5, H'BCBD, H'BCC5, H'BCCD
+             */
+            candidate_set_value_acked(logical_index, value);
+            break;
+        case 0x01u:
+            /* read_value: initial/idle-path primary table read only, followed by an odd response staging sequence
+             * availability: valid checksum/no RX physical error && FAA2 == 0 && F861.bit7 == 0
+             * note: Only accepted on the initial/idle dispatcher path: valid checksum/no RX error, FAA2 == 0, and F861.bit7 == 0.
+             * note: BCD7 stages F850=0x04, writes F851 from F861 and then overwrites F851 from F862.
+             * note: BCD7 reads the primary table word at E000 + 2*selector; F854 receives the low byte and F853 receives the high byte.
+             * note: F852 is not freshly written in the BCD7 handler, so do not describe the response as a fixed 04 00 QQ hi lo frame.
+             * candidate effect: table_read_candidate; target primary_value_table_candidate; table H'E000
+             * candidate effect: response_staging_candidate; stage F850-F854 and call loc_BA26
+             * evidence: H'BC08, H'BC0C, H'BC24, H'BC26, H'BCD7, H'BCE0, H'BCE8, H'BCF0, H'BCF6, H'BCDC, H'BCE4, H'BCFA
+             */
+            if ((RX_FRAME(1) & 0x80u) != 0u) {
+                candidate_unknown_command(command, logical_index, value);
+                break;
+            }
+            candidate_read_value(logical_index, value);
+            break;
+        case 0x02u:
+            /* clear_or_abort: candidate clear/abort path with no immediate response builder
+             * availability: valid checksum/no RX physical error && FAA2 == 0
+             * candidate effect: state_clear_candidate; target serial_session_flags_candidate; clear bit 7; state H'FAA2
+             * evidence: H'BC08, H'BC0C, H'BC29, H'BC2B
+             */
+            candidate_clear_or_abort(logical_index, value);
+            break;
+        case 0x07u:
+            /* retransmit_or_error_reply: candidate retransmit path; retry/error handling also builds a command 0x07 RX-payload echo
+             * availability: valid checksum/no RX physical error && FAA2 == 0 OR valid checksum/no RX physical error && FAA2 != 0
+             * note: loc_BE4D is a retry/error echo path: F850=0x07 and F861-F864 are copied into F851-F854 before loc_BA26.
+             * note: Observed frame 07 80 40 20 90 2D means RX bytes F861-F864 were 80 40 20 90; it is not a table value.
+             * candidate effect: retransmit_candidate; target TX staging bytes H'F850-H'F854 before loc_BA26; source previous TX frame bytes H'F858-H'F85C
+             * candidate effect: retry_error_echo_candidate; target F850=0x07, F851-F854=F861-F864 before loc_BA26; source RX payload bytes F861-F864; 07 80 40 20 90 2D echoes RX payload 80 40 20 90; it is not a table value
+             * candidate effect: response_staging_candidate; stage F850-F854 and call loc_BA26
+             * evidence: H'BC08, H'BC0C, H'BC2E, H'BC30, H'BC54, H'BC56, H'BE09, H'BE11, H'BE19, H'BE22
+             */
+            candidate_retransmit_or_error_reply(logical_index, value);
+            break;
+        default:
+            candidate_unknown_command(command, logical_index, value);
+            break;
+        }
+        return;
+    }
+
+    /* Continuation dispatcher: FAA2 != 0. */
     switch (command) {
-    case 0x00u:
-        /* set_value_acked: candidate write of RX[3:4] into primary/current tables, followed by a response
-         * candidate effect: table_write_candidate; target primary_value_table_candidate; source RX[3:4] value bytes, with an observed 0x80 fallback when decoded index is zero; table H'E000
-         * candidate effect: table_write_candidate; target current_value_table_candidate; source same candidate value written to the primary table; table H'E800
-         * candidate effect: flag_update_candidate; target per_index_flag_table_candidate; set bit 7; table H'EC00
-         * evidence: H'BC08, H'BC0C, H'BC20, H'BC22, H'BCB0, H'BCB9, H'BCC1, H'BCC9, H'BCB5, H'BCBD, H'BCC5, H'BCCD
-         */
-        candidate_set_value_acked(logical_index, value);
-        break;
-    case 0x01u:
-        /* read_value: candidate read from the primary table, followed by a response carrying the value
-         * candidate effect: table_read_candidate; target primary_value_table_candidate; table H'E000
-         * candidate effect: response_staging_candidate; stage F850-F854 and call loc_BA26
-         * evidence: H'BC08, H'BC0C, H'BC24, H'BC26, H'BCB0, H'BCB9, H'BCC1, H'BCC9, H'BCD7, H'BCE0, H'BCE8, H'BCF0, H'BCF6, H'BCB5, H'BCBD, H'BCC5, H'BCDC, H'BCE4, H'BCFA
-         */
-        candidate_read_value(logical_index, value);
-        break;
-    case 0x02u:
-        /* clear_or_abort: candidate clear/abort path with no immediate response builder
-         * candidate effect: state_clear_candidate; target serial_session_flags_candidate; clear bit 7; state H'FAA2
-         * evidence: H'BC08, H'BC0C, H'BC29, H'BC2B
-         */
-        candidate_clear_or_abort(logical_index, value);
-        break;
     case 0x04u:
         /* set_value_no_immediate_reply: candidate write/update path that stores a value without an immediate serial response
+         * availability: valid checksum/no RX physical error && FAA2 != 0
          * candidate effect: table_write_candidate; target primary_value_table_candidate; source RX[3:4] value bytes, with an observed 0x80 fallback when decoded index is zero; table H'E000
          * candidate effect: flag_update_candidate; target per_index_flag_table_candidate; set bit 7; table H'EC00
          * evidence: H'BC08, H'BC0C, H'BC45, H'BC47
@@ -372,14 +434,20 @@ void sci1_process_candidate_protocol_command(void)
         candidate_set_value_no_immediate_reply(logical_index, value);
         break;
     case 0x05u:
-        /* ack_or_clear_pending: candidate pending/event acknowledgement path
+        /* ack_or_clear_pending: continuation-only conditional acknowledgement/session clear path
-         * candidate effect: pending_acknowledgement_candidate; target selected event/pending state; clear selected pending flags and then clear serial session state
+         * availability: valid checksum/no RX physical error && FAA2 != 0
+         * note: Only accepted on the continuation dispatcher path when FAA2 != 0.
+         * note: For selector 0x0040, frame 05 00 40 00 00 1F performs no response staging.
+         * note: The handler clears FAA3/FAA2; F9B5 advances only when FAA2.bit3 was set from a queued report.
+         * note: If FAA2 == 0, command 5 falls through the initial dispatcher instead of doing acknowledgement work.
+         * candidate effect: conditional_ack_session_clear_candidate; target selected event/pending state; when FAA2 != 0, clear FAA3/FAA2; advance F9B5 only if FAA2.bit3 was set from queued-report state; selector 0x0040 stages no response; selector H'0040 has no response
          * evidence: H'BC08, H'BC0C, H'BC4A, H'BC4C
          */
         candidate_ack_or_clear_pending(logical_index, value);
         break;
     case 0x06u:
         /* set_secondary_value: candidate secondary-table value write path
+         * availability: valid checksum/no RX physical error && FAA2 != 0
          * candidate effect: table_write_candidate; target secondary_value_table_candidate; source RX[3:4] value bytes; table H'E400
          * candidate effect: flag_update_candidate; target per_index_flag_table_candidate; set bit 6; table H'EC00
          * evidence: H'BC08, H'BC0C, H'BC4F, H'BC51
@@ -387,8 +455,12 @@ void sci1_process_candidate_protocol_command(void)
         candidate_set_secondary_value(logical_index, value);
         break;
     case 0x07u:
-        /* retransmit_or_error_reply: candidate retransmit/NAK-style path; error handling also builds command 0x07 responses
+        /* retransmit_or_error_reply: candidate retransmit path; retry/error handling also builds a command 0x07 RX-payload echo
+         * availability: valid checksum/no RX physical error && FAA2 == 0 OR valid checksum/no RX physical error && FAA2 != 0
+         * note: loc_BE4D is a retry/error echo path: F850=0x07 and F861-F864 are copied into F851-F854 before loc_BA26.
+         * note: Observed frame 07 80 40 20 90 2D means RX bytes F861-F864 were 80 40 20 90; it is not a table value.
          * candidate effect: retransmit_candidate; target TX staging bytes H'F850-H'F854 before loc_BA26; source previous TX frame bytes H'F858-H'F85C
+         * candidate effect: retry_error_echo_candidate; target F850=0x07, F851-F854=F861-F864 before loc_BA26; source RX payload bytes F861-F864; 07 80 40 20 90 2D echoes RX payload 80 40 20 90; it is not a table value
          * candidate effect: response_staging_candidate; stage F850-F854 and call loc_BA26
          * evidence: H'BC08, H'BC0C, H'BC2E, H'BC30, H'BC54, H'BC56, H'BE09, H'BE11, H'BE19, H'BE22
          */

h8536/bench_connect_lcd.py

@@ -23,12 +23,22 @@ COMMAND7_REPEAT_FRAME = bytes.fromhex("07000000005D")
 
 @dataclass
 class FrameDetector:
+    sync_mode: str = "checksum"
     buffer: bytearray = field(default_factory=bytearray)
     frames: list[bytes] = field(default_factory=list)
     labels: Counter[str] = field(default_factory=Counter)
+    dropped_bytes: int = 0
+    resync_events: int = 0
 
     def feed(self, data: bytes) -> list[tuple[bytes, str]]:
         self.buffer.extend(data)
+        if self.sync_mode == "fixed":
+            return self._feed_fixed()
+        if self.sync_mode != "checksum":
+            raise ValueError(f"unknown frame sync mode {self.sync_mode!r}")
+        return self._feed_checksum_resync()
+
+    def _feed_fixed(self) -> list[tuple[bytes, str]]:
         detected = []
         while len(self.buffer) >= FRAME_LENGTH:
             frame = bytes(self.buffer[:FRAME_LENGTH])
@@ -40,6 +50,35 @@ class FrameDetector:
             detected.append((frame, label))
         return detected
 
+    def _feed_checksum_resync(self) -> list[tuple[bytes, str]]:
+        detected = []
+        while len(self.buffer) >= FRAME_LENGTH:
+            offset = _next_sync_offset(self.buffer)
+            if offset is None:
+                self._drop_unsynced_prefix(len(self.buffer) - (FRAME_LENGTH - 1))
+                break
+            if offset:
+                self._drop_unsynced_prefix(offset)
+            frame = bytes(self.buffer[:FRAME_LENGTH])
+            if not frame_checksum_ok(frame):
+                self._drop_unsynced_prefix(1)
+                continue
+            del self.buffer[:FRAME_LENGTH]
+            label = label_frame(frame)
+            self.frames.append(frame)
+            if label:
+                self.labels[label] += 1
+            detected.append((frame, label))
+        return detected
+
+    def _drop_unsynced_prefix(self, count: int) -> None:
+        count = max(0, min(count, len(self.buffer)))
+        if not count:
+            return
+        del self.buffer[:count]
+        self.dropped_bytes += count
+        self.resync_events += 1
+
 
 class BenchLogger:
     def __init__(self, path: Path, stdout: TextIO = sys.stdout) -> None:
@@ -113,10 +152,46 @@ def label_frame(frame: bytes) -> str:
     if label:
         return label
     if frame_checksum_ok(frame):
+        if frame[0] == 0x04:
+            return "table_readback_candidate"
+        if frame[0] == 0x07:
+            return "visible_report_candidate"
         return "checksum_ok_unlabeled"
     return "checksum_bad_or_unaligned"
 
 
+def _next_sync_offset(buffer: bytearray) -> int | None:
+    scored_offsets: list[tuple[int, int]] = []
+    for offset in range(0, len(buffer) - FRAME_LENGTH + 1):
+        frame = bytes(buffer[offset : offset + FRAME_LENGTH])
+        if not frame_checksum_ok(frame):
+            continue
+        if offset == 0 and not _looks_like_shifted_heartbeat(frame):
+            return 0
+        label = label_frame(frame)
+        scored_offsets.append((_sync_score(frame, label), offset))
+    if not scored_offsets:
+        return None
+    return min(scored_offsets)[1]
+
+
+def _sync_score(frame: bytes, label: str) -> int:
+    if label and label not in {"checksum_ok_unlabeled", "checksum_bad_or_unaligned"}:
+        return 0
+    if frame[0] in {0x00, 0x02, 0x04, 0x07}:
+        return 100
+    return 200
+
+
+def _looks_like_shifted_heartbeat(frame: bytes) -> bool:
+    return frame in {
+        bytes.fromhex("00000080DA00"),
+        bytes.fromhex("000080DA0000"),
+        bytes.fromhex("0080DA000000"),
+        bytes.fromhex("80DA00000000"),
+    }
+
+
 def default_log_path() -> Path:
     return Path("captures") / f"bench-connect-lcd-sequence-{datetime.now().strftime('%Y%m%d-%H%M%S')}.txt"
 
@@ -141,6 +216,7 @@ def build_arg_parser() -> argparse.ArgumentParser:
     parser.add_argument("--post-sequence-read", type=float, default=3.0, help="seconds to listen after the sequence")
     parser.add_argument("--repeat", type=int, default=1, help="times to send the frame sequence in the same power session")
     parser.add_argument("--frame", action="append", type=parse_frame, help="override preset with a custom frame; repeatable")
+    parser.add_argument("--sync", choices=("checksum", "fixed"), default="checksum", help="RX frame sync strategy")
     parser.add_argument("--two-frame", action="store_true", help="send only the first two CONNECT candidate frames")
     parser.add_argument("--command7-after", action="store_true", help="send command-7 repeat probe after the sequence")
     parser.add_argument("--pre-sequence-drain", type=float, default=0.250, help="seconds to drain/log RX immediately before sending")
@@ -169,7 +245,7 @@ def main(argv: list[str] | None = None, *, stdout: TextIO = sys.stdout) -> int:
 
     serial = _import_serial()
     logger = BenchLogger(log_path, stdout=stdout)
-    detector = FrameDetector()
+    detector = FrameDetector(sync_mode=args.sync)
     try:
         logger.emit("CONNECT LCD bench sequence")
         logger.emit(f"device={args.port} {args.baud} 8N1 relay={args.relay_port} {args.relay_baud}")
@@ -186,7 +262,7 @@ def main(argv: list[str] | None = None, *, stdout: TextIO = sys.stdout) -> int:
                     _relay_command(relay, args.power_off_command, logger)
                     time.sleep(args.off_seconds)
                     device.reset_input_buffer()
-                    detector = FrameDetector()
+                    detector = FrameDetector(sync_mode=args.sync)
                     _relay_command(relay, args.power_on_command, logger)
                 else:
                     device.reset_input_buffer()
@@ -256,9 +332,16 @@ def _read_for(device, detector: FrameDetector, logger: BenchLogger, seconds: flo
         waiting = getattr(device, "in_waiting", 0)
         data = device.read(waiting or 1)
         if data:
+            dropped_before = detector.dropped_bytes
             logger.chunk("RX", data)
             for frame, label in detector.feed(data):
                 logger.event(f"DETECT {label} {format_frame(frame)}")
+            dropped_now = detector.dropped_bytes - dropped_before
+            if dropped_now:
+                logger.event(
+                    f"RESYNC dropped_bytes={dropped_now} total_dropped={detector.dropped_bytes} "
+                    f"buffered={len(detector.buffer)}"
+                )
 
 
 def _wait_for_ready(
@@ -310,6 +393,7 @@ def _summary(detector: FrameDetector, logger: BenchLogger) -> None:
     logger.emit()
     logger.emit("Summary")
     logger.emit(f"rx_frames={len(detector.frames)} trailing_unframed_bytes={len(detector.buffer)}")
+    logger.emit(f"resync_events={detector.resync_events} dropped_bytes={detector.dropped_bytes}")
     for label, count in sorted(detector.labels.items()):
         logger.emit(f"{label}={count}")
 

h8536/serial_ack_probe.py

@@ -153,6 +153,7 @@ def _summary(detector: FrameDetector, logger: BenchLogger, target: bytes, trigge
     logger.emit()
     logger.emit("Summary")
     logger.emit(f"rx_frames={len(detector.frames)} trailing_unframed_bytes={len(detector.buffer)}")
+    logger.emit(f"resync_events={detector.resync_events} dropped_bytes={detector.dropped_bytes}")
     logger.emit(f"target_before_ack={sum(1 for frame in trigger_frames if frame == target)}")
     logger.emit(f"target_after_ack={sum(1 for frame in post_ack_frames if frame == target)}")
     labels = Counter(label for label in detector.labels.elements())

h8536/serial_pseudocode.py

@@ -385,6 +385,17 @@ def _semantics_lines(
             " * dispatch: command_low3 = RX_FRAME(0) & 0x07"
             + (f"; observed {values}" if values else ""),
         )
+        state_split = dispatch.get("state_split") or dispatch.get("dispatcher_split")
+        if isinstance(state_split, dict):
+            initial = ", ".join(str(item) for item in state_split.get("initial_idle_commands_hex", []) if item)
+            continuation = ", ".join(str(item) for item in state_split.get("continuation_commands_hex", []) if item)
+            lines.append(
+                " * dispatcher split: FAA2 == 0 accepts initial/idle commands "
+                f"{initial or 'none'}; FAA2 != 0 accepts continuation commands {continuation or 'none'}",
+            )
+            caveat = str(state_split.get("caveat") or "").strip()
+            if caveat:
+                lines.append(f" * dispatcher caveat: {_comment_text(caveat)}")
         if opts.include_evidence:
             lines.append(f" * dispatch evidence: {_hex_join(dispatch.get('evidence_addresses_hex'))}")
 
@@ -405,6 +416,11 @@ def _semantics_lines(
             handler = command.get("handler_start_hex") or "multiple"
             responses = ", ".join(str(item) for item in command.get("response_candidates", [])) or "none"
             lines.append(f" * - {value} {name}: {summary}; handler {handler}; responses {responses}")
+            availability = _comment_text(str(command.get("availability_summary") or ""))
+            if availability:
+                lines.append(f" *   availability: {availability}")
+            for note in command.get("semantic_notes", []):
+                lines.append(f" *   note: {_comment_text(str(note))}")
     lines.extend(_command_effect_comment_lines(protocol.get("command_effects"), opts, prefix=" * "))
     lines.extend(_response_schema_comment_lines(_schema_list(protocol), opts, prefix=" * "))
     lines.extend(_table_map_comment_lines(_table_map_list(protocol), opts, prefix=" * "))
@@ -458,9 +474,51 @@ def _semantics_lines(
             "    u16 logical_index = sci1_rx_candidate_logical_index();",
             "    u16 value = sci1_rx_candidate_value();",
             "",
-            "    switch (command) {",
         ],
     )
+    lines.extend(_command_dispatch_switch_lines(commands, opts))
+    return lines
+
+
+def _command_dispatch_switch_lines(commands: list[JsonObject], opts: SerialPseudocodeOptions) -> list[str]:
+    initial = [
+        command for command in commands
+        if _command_has_availability(command, "initial_idle_dispatch")
+    ]
+    continuation = [
+        command for command in commands
+        if _command_has_availability(command, "continuation_dispatch")
+    ]
+    if not initial and not continuation:
+        return _flat_command_switch_lines(commands, opts, indent="    ") + ["}", ""]
+
+    lines = [
+        "    bool session_active = MEM8[0xFAA2u] != 0u;",
+        "",
+        "    if (!session_active) {",
+        "        /* Initial/idle dispatcher: valid checksum/no RX error, FAA2 == 0. */",
+    ]
+    lines.extend(_flat_command_switch_lines(initial, opts, indent="        "))
+    lines.extend(
+        [
+            "        return;",
+            "    }",
+            "",
+            "    /* Continuation dispatcher: FAA2 != 0. */",
+        ],
+    )
+    lines.extend(_flat_command_switch_lines(continuation, opts, indent="    "))
+    lines.extend(["}", ""])
+    return lines
+
+
+def _flat_command_switch_lines(
+    commands: list[JsonObject],
+    opts: SerialPseudocodeOptions,
+    *,
+    indent: str,
+) -> list[str]:
+    lines = [f"{indent}switch (command) {{"]
     for command in commands:
         value = command.get("command_value")
         if not isinstance(value, int):
@@ -468,28 +526,50 @@ def _semantics_lines(
         name = _safe_identifier(str(command.get("name_candidate") or f"command_{value:02X}"))
         summary = _comment_text(str(command.get("summary") or "candidate command semantics unknown"))
         evidence = _hex_join(command.get("evidence_addresses_hex"))
-        lines.append(f"    case 0x{value:02X}u:")
+        lines.append(f"{indent}case 0x{value:02X}u:")
-        lines.append(f"        /* {name}: {summary}")
+        lines.append(f"{indent}    /* {name}: {summary}")
+        availability = _comment_text(str(command.get("availability_summary") or ""))
+        if availability:
+            lines.append(f"{indent}     * availability: {availability}")
+        for note in command.get("semantic_notes", []):
+            lines.append(f"{indent}     * note: {_comment_text(str(note))}")
         for effect_line in _command_effect_switch_lines(command):
-            lines.append(f"         * {effect_line}")
+            lines.append(f"{indent}     * {effect_line}")
         if opts.include_evidence and evidence:
-            lines.append(f"         * evidence: {evidence}")
+            lines.append(f"{indent}     * evidence: {evidence}")
-        lines.append("         */")
+        lines.append(f"{indent}     */")
-        lines.append(f"        candidate_{name}(logical_index, value);")
+        if value == 0x01:
-        lines.append("        break;")
+            lines.append(f"{indent}    if ((RX_FRAME(1) & 0x80u) != 0u) {{")
+            lines.append(f"{indent}        candidate_unknown_command(command, logical_index, value);")
+            lines.append(f"{indent}        break;")
+            lines.append(f"{indent}    }}")
+        lines.append(f"{indent}    candidate_{name}(logical_index, value);")
+        lines.append(f"{indent}    break;")
     lines.extend(
         [
-            "    default:",
+            f"{indent}default:",
-            "        candidate_unknown_command(command, logical_index, value);",
+            f"{indent}    candidate_unknown_command(command, logical_index, value);",
-            "        break;",
+            f"{indent}    break;",
-            "    }",
+            f"{indent}}}",
-            "}",
-            "",
         ],
     )
     return lines
 
 
+def _command_has_availability(command: JsonObject, availability: str) -> bool:
+    value = command.get("availability")
+    if value == availability:
+        return True
+    if isinstance(value, list) and availability in value:
+        return True
+    conditions = " ".join(str(item) for item in command.get("availability_conditions", []))
+    if availability == "initial_idle_dispatch":
+        return "FAA2 == 0" in conditions
+    if availability == "continuation_dispatch":
+        return "FAA2 != 0" in conditions
+    return False
+
+
 def _command_effect_comment_lines(
     value: object,
     opts: SerialPseudocodeOptions,
@@ -528,6 +608,8 @@ def _response_schema_comment_lines(
         response_id = schema.get("response_id") or schema.get("call_address_hex") or "candidate_response"
         byte_text = _response_schema_summary(schema)
         lines.append(f"{prefix}- {response_id}: {byte_text}")
+        for note in schema.get("semantic_notes", []):
+            lines.append(f"{prefix}  note: {_comment_text(str(note))}")
         evidence = _hex_join(schema.get("evidence_addresses_hex"))
         if opts.include_evidence and evidence:
             lines.append(f"{prefix}  evidence: {evidence}")
@@ -612,6 +694,13 @@ def _retry_error_comment_lines(
         threshold = retry.get("threshold_candidate", "?")
         summary = _comment_text(str(retry.get("summary") or "candidate retry path"))
         lines.append(f"{prefix}- retry path: counter {counter}, threshold {threshold}; {summary}")
+        echo = retry.get("echo_response_candidate")
+        if isinstance(echo, dict):
+            staging = _comment_text(str(echo.get("staging_candidate") or "retry/error echo staging"))
+            caveat = _comment_text(str(echo.get("observed_frame_caveat") or ""))
+            lines.append(f"{prefix}  echo path: {echo.get('entry_label', 'loc_BE4D')}: {staging}")
+            if caveat:
+                lines.append(f"{prefix}  echo caveat: {caveat}")
     if isinstance(command_07, dict):
         summary = _comment_text(str(command_07.get("summary") or "candidate command 0x07 path"))
         lines.append(f"{prefix}- command 0x07 path: {summary}")
@@ -987,6 +1076,8 @@ def _effect_summary(effect: JsonObject) -> str:
     operation = effect.get("operation_candidate")
     table = effect.get("table_base_hex")
     state = effect.get("state_address_hex")
+    selector = effect.get("selector_without_response_hex")
+    observed = effect.get("observed_frame_caveat")
     if target:
         parts.append(f"target {target}")
     if source:
@@ -997,6 +1088,10 @@ def _effect_summary(effect: JsonObject) -> str:
         parts.append(f"table {table}")
     if state:
         parts.append(f"state {state}")
+    if selector:
+        parts.append(f"selector {selector} has no response")
+    if observed:
+        parts.append(str(observed))
     return _comment_text("; ".join(parts))
 
 

h8536/serial_scenario.py

@@ -0,0 +1,509 @@
+from __future__ import annotations
+
+import argparse
+import json
+import sys
+import time
+from dataclasses import dataclass, field
+from datetime import datetime
+from pathlib import Path
+from typing import Any, TextIO
+
+from .bench_connect_lcd import (
+    BenchLogger,
+    FrameDetector,
+    _import_serial,
+    _read_for,
+    _relay_command,
+    _relay_settle,
+    _send_frame,
+    _wait_for_ready,
+    format_frame,
+    frame_checksum_ok,
+    parse_frame,
+)
+from .serial_table_dump import build_read_frame, decode_table_read_response
+
+
+DEFAULT_ACK_TARGET = bytes.fromhex("07804020902D")
+DEFAULT_ACK_FRAME = bytes.fromhex("05004000001F")
+
+
+@dataclass
+class ScenarioContext:
+    args: argparse.Namespace
+    logger: BenchLogger
+    detector: FrameDetector
+    device: Any
+    relay: Any | None = None
+    table_rows: list[dict[str, Any]] = field(default_factory=list)
+    target_counts: dict[str, int] = field(default_factory=dict)
+    tx_records: list[dict[str, Any]] = field(default_factory=list)
+    ack_sent: int = 0
+    abort_requested: bool = False
+
+
+def default_log_path(scenario: dict[str, Any]) -> Path:
+    name = str(scenario.get("name") or "serial-scenario").strip() or "serial-scenario"
+    safe_name = "".join(char if char.isalnum() or char in "-_" else "-" for char in name)
+    return Path("captures") / f"{safe_name}-{datetime.now().strftime('%Y%m%d-%H%M%S')}.txt"
+
+
+def build_arg_parser() -> argparse.ArgumentParser:
+    parser = argparse.ArgumentParser(
+        description="Run JSON-described serial bench scenarios against the real RCP."
+    )
+    parser.add_argument("scenario", type=Path, help="JSON scenario file")
+    parser.add_argument("--port", default="COM5", help="RS232 serial port connected to the RCP")
+    parser.add_argument("--baud", type=int, default=38400, help="RCP serial baud rate")
+    parser.add_argument("--relay-port", default="COM6", help="Pico relay serial port")
+    parser.add_argument("--relay-baud", type=int, default=115200, help="Pico relay serial baud rate")
+    parser.add_argument("--no-power-cycle", action="store_true", help="skip power_cycle actions")
+    parser.add_argument("--power-off-command", default="off", help="relay command used to remove DUT power")
+    parser.add_argument("--power-on-command", default="on", help="relay command used to apply DUT power")
+    parser.add_argument("--relay-settle", type=float, default=2.0, help="seconds to wait after opening the relay port")
+    parser.add_argument("--sync", choices=("checksum", "fixed"), default="checksum", help="RX frame sync strategy")
+    parser.add_argument("--log", type=Path, help="capture log path")
+    parser.add_argument("--result-json", type=Path, help="write machine-readable scenario summary")
+    parser.add_argument("--dry-run", action="store_true", help="print the plan without opening serial ports")
+    return parser
+
+
+def main(argv: list[str] | None = None, *, stdout: TextIO = sys.stdout) -> int:
+    args = build_arg_parser().parse_args(argv)
+    scenario = load_scenario(args.scenario)
+    log_path = args.log or default_log_path(scenario)
+
+    if args.dry_run:
+        _print_dry_run(args, scenario, log_path, stdout)
+        return 0
+
+    serial = _import_serial()
+    logger = BenchLogger(log_path, stdout=stdout)
+    detector = FrameDetector(sync_mode=args.sync)
+    try:
+        logger.emit("Serial bench scenario")
+        logger.emit(f"name={scenario.get('name', args.scenario.stem)}")
+        logger.emit(f"device={args.port} {args.baud} 8N1 relay={args.relay_port} {args.relay_baud} sync={args.sync}")
+        logger.emit(f"log={log_path}")
+        with serial.Serial(args.port, args.baud, bytesize=8, parity="N", stopbits=1, timeout=0.05) as device:
+            ctx = ScenarioContext(args=args, logger=logger, detector=detector, device=device)
+            try:
+                for index, step in enumerate(_scenario_steps(scenario), start=1):
+                    if ctx.abort_requested:
+                        logger.event("SCENARIO_ABORT requested by prior step")
+                        break
+                    action, spec = _normalize_step(step)
+                    logger.event(f"STEP {index} {action}")
+                    _run_step(ctx, action, spec)
+            finally:
+                if ctx.relay is not None:
+                    ctx.relay.close()
+        _emit_summary(ctx, logger)
+        if args.result_json:
+            _write_result_json(args.result_json, scenario, log_path, ctx)
+        return 0
+    finally:
+        logger.close()
+
+
+def load_scenario(path: Path) -> dict[str, Any]:
+    with path.open("r", encoding="utf-8") as handle:
+        scenario = json.load(handle)
+    if not isinstance(scenario, dict):
+        raise SystemExit("scenario root must be a JSON object")
+    if not isinstance(scenario.get("steps"), list):
+        raise SystemExit("scenario must contain a steps array")
+    return scenario
+
+
+def _scenario_steps(scenario: dict[str, Any]) -> list[Any]:
+    steps = scenario.get("steps", [])
+    if not isinstance(steps, list):
+        raise SystemExit("scenario steps must be an array")
+    return steps
+
+
+def _normalize_step(step: Any) -> tuple[str, dict[str, Any]]:
+    if isinstance(step, str):
+        return step, {}
+    if not isinstance(step, dict):
+        raise SystemExit(f"invalid scenario step {step!r}")
+    if "action" in step:
+        spec = dict(step)
+        action = str(spec.pop("action"))
+        return action, spec
+    if len(step) == 1:
+        action, value = next(iter(step.items()))
+        if value is None:
+            return str(action), {}
+        if isinstance(value, dict):
+            return str(action), dict(value)
+        return str(action), {"value": value}
+    raise SystemExit(f"scenario step needs an action: {step!r}")
+
+
+def _run_step(ctx: ScenarioContext, action: str, spec: dict[str, Any]) -> None:
+    if action == "power_cycle":
+        _step_power_cycle(ctx, spec)
+    elif action == "wait_ready":
+        ready = _wait_for_ready(
+            ctx.device,
+            ctx.detector,
+            ctx.logger,
+            float(spec.get("timeout", 10.0)),
+            int(spec.get("heartbeats", 2)),
+        )
+        if spec.get("require", False) and not ready:
+            raise SystemExit(2)
+    elif action in {"drain", "listen", "wait"}:
+        _listen(ctx, float(spec.get("seconds", spec.get("value", 0.0))))
+    elif action == "send":
+        frame = _parse_required_frame(spec.get("frame"))
+        label = str(spec.get("label", "send"))
+        _send_and_record(ctx, frame, label)
+        if float(spec.get("listen", 0.0)) > 0:
+            _listen(ctx, float(spec.get("listen", 0.0)))
+    elif action == "wait_for":
+        _step_wait_for(ctx, spec)
+    elif action == "table_sweep":
+        _step_table_sweep(ctx, spec)
+    elif action == "repeat":
+        _step_repeat(ctx, spec)
+    else:
+        raise SystemExit(f"unknown scenario action {action!r}")
+
+
+def _step_power_cycle(ctx: ScenarioContext, spec: dict[str, Any]) -> None:
+    if ctx.args.no_power_cycle:
+        ctx.logger.event("POWER_CYCLE skipped by --no-power-cycle")
+        ctx.device.reset_input_buffer()
+        ctx.detector = FrameDetector(sync_mode=ctx.args.sync)
+        return
+    serial = _import_serial()
+    if ctx.relay is None:
+        ctx.relay = serial.Serial(ctx.args.relay_port, ctx.args.relay_baud, timeout=0.25)
+        _relay_settle(ctx.relay, float(spec.get("relay_settle", ctx.args.relay_settle)), ctx.logger)
+    off_command = str(spec.get("off_command", ctx.args.power_off_command))
+    on_command = str(spec.get("on_command", ctx.args.power_on_command))
+    _relay_command(ctx.relay, off_command, ctx.logger)
+    time.sleep(float(spec.get("off_seconds", 1.5)))
+    ctx.device.reset_input_buffer()
+    ctx.detector = FrameDetector(sync_mode=ctx.args.sync)
+    _relay_command(ctx.relay, on_command, ctx.logger)
+
+
+def _step_wait_for(ctx: ScenarioContext, spec: dict[str, Any]) -> None:
+    targets = _parse_frame_list(spec.get("frames", spec.get("frame")))
+    timeout = float(spec.get("timeout", 1.0))
+    require = bool(spec.get("require", False))
+    ctx.logger.event(
+        "WAIT_FOR "
+        + ",".join(format_frame(frame) for frame in targets)
+        + f" timeout={timeout:.3f}s"
+    )
+    found = _listen_until(ctx, timeout, targets)
+    if require and not found:
+        raise SystemExit(3)
+
+
+def _step_repeat(ctx: ScenarioContext, spec: dict[str, Any]) -> None:
+    count = max(0, int(spec.get("count", 1)))
+    steps = spec.get("steps", [])
+    if not isinstance(steps, list):
+        raise SystemExit("repeat step requires a steps array")
+    for repeat_index in range(count):
+        ctx.logger.event(f"REPEAT {repeat_index + 1}/{count}")
+        for step in steps:
+            action, child_spec = _normalize_step(step)
+            _run_step(ctx, action, child_spec)
+
+
+def _step_table_sweep(ctx: ScenarioContext, spec: dict[str, Any]) -> None:
+    selectors = _selector_list(spec)
+    gap = float(spec.get("gap", 0.080))
+    ack = _ack_config(spec.get("ack_on", {}))
+    ctx.logger.event(
+        f"TABLE_SWEEP selectors={len(selectors)} gap={gap:.3f}s "
+        f"ack_targets={len(ack['targets'])} ack_frame={format_frame(ack['frame'])}"
+    )
+    for selector in selectors:
+        if ctx.abort_requested:
+            ctx.logger.event("TABLE_SWEEP_ABORT stopping before next selector")
+            break
+        frame = build_read_frame(selector)
+        ctx.logger.event(f"READ selector=0x{selector:03X} frame={format_frame(frame)}")
+        _send_and_record(ctx, frame, f"read_0x{selector:03X}")
+        _listen_with_ack(ctx, gap, selector, ack)
+
+
+def _ack_config(raw: Any) -> dict[str, Any]:
+    spec = raw if isinstance(raw, dict) else {}
+    targets = _parse_frame_list(spec.get("frames", spec.get("frame", DEFAULT_ACK_TARGET)))
+    return {
+        "targets": set(targets),
+        "frame": _parse_optional_frame(spec.get("ack_frame"), DEFAULT_ACK_FRAME),
+        "guard": float(spec.get("ack_guard", 0.020)),
+        "poll_interval": float(spec.get("poll_interval", 0.005)),
+        "post_read": float(spec.get("post_ack_read", 0.250)),
+        "once_per_selector": bool(spec.get("once_per_selector", True)),
+        "enabled": bool(spec.get("enabled", True)),
+        "max_acks": _optional_int(spec.get("max_acks")),
+        "max_target_hits": _optional_int(spec.get("max_target_hits")),
+        "abort_on_limit": bool(spec.get("abort_on_limit", True)),
+    }
+
+
+def _listen_with_ack(
+    ctx: ScenarioContext,
+    seconds: float,
+    selector: int,
+    ack: dict[str, Any],
+) -> list[bytes]:
+    deadline = time.monotonic() + max(0.0, seconds)
+    observed: list[bytes] = []
+    acked_targets: set[bytes] = set()
+    while time.monotonic() < deadline:
+        frames = _read_available(ctx, selector=selector)
+        observed.extend(frames)
+        if not frames:
+            sleep_for = min(max(0.001, ack["poll_interval"]), max(0.0, deadline - time.monotonic()))
+            if sleep_for > 0:
+                time.sleep(sleep_for)
+            continue
+        if not ack["enabled"]:
+            continue
+        for frame in frames:
+            if frame not in ack["targets"]:
+                continue
+            _count_target(ctx, frame)
+            if _ack_limit_reached(ctx, ack):
+                ctx.logger.event("ACK_LIMIT reached before ACK send")
+                if ack["abort_on_limit"]:
+                    ctx.abort_requested = True
+                    return observed
+                continue
+            if ack["once_per_selector"] and frame in acked_targets:
+                continue
+            acked_targets.add(frame)
+            if ack["guard"] > 0:
+                observed.extend(_listen(ctx, ack["guard"], selector=selector))
+            _send_and_record(ctx, ack["frame"], "ack")
+            ctx.ack_sent += 1
+            if _ack_limit_reached(ctx, ack):
+                ctx.logger.event("ACK_LIMIT reached after ACK send")
+                if ack["abort_on_limit"]:
+                    ctx.abort_requested = True
+            if ack["post_read"] > 0:
+                observed.extend(_listen(ctx, ack["post_read"], selector=selector))
+            if ctx.abort_requested:
+                return observed
+    return observed
+
+
+def _listen_until(ctx: ScenarioContext, seconds: float, targets: set[bytes]) -> bool:
+    deadline = time.monotonic() + max(0.0, seconds)
+    while time.monotonic() < deadline:
+        interval = min(0.050, max(0.0, deadline - time.monotonic()))
+        if interval <= 0:
+            break
+        for frame in _listen(ctx, interval):
+            if frame in targets:
+                ctx.logger.event(f"WAIT_FOR_MATCH {format_frame(frame)}")
+                return True
+    return False
+
+
+def _listen(ctx: ScenarioContext, seconds: float, *, selector: int | None = None) -> list[bytes]:
+    before = len(ctx.detector.frames)
+    _read_for(ctx.device, ctx.detector, ctx.logger, seconds)
+    frames = ctx.detector.frames[before:]
+    _record_table_rows(ctx, frames, selector)
+    return frames
+
+
+def _read_available(ctx: ScenarioContext, *, selector: int | None = None) -> list[bytes]:
+    waiting = getattr(ctx.device, "in_waiting", 0)
+    if not waiting:
+        return []
+    dropped_before = ctx.detector.dropped_bytes
+    data = ctx.device.read(waiting)
+    if not data:
+        return []
+    ctx.logger.chunk("RX", data)
+    detected = ctx.detector.feed(data)
+    for frame, label in detected:
+        ctx.logger.event(f"DETECT {label} {format_frame(frame)}")
+    dropped_now = ctx.detector.dropped_bytes - dropped_before
+    if dropped_now:
+        ctx.logger.event(
+            f"RESYNC dropped_bytes={dropped_now} total_dropped={ctx.detector.dropped_bytes} "
+            f"buffered={len(ctx.detector.buffer)}"
+        )
+    frames = [frame for frame, _label in detected]
+    _record_table_rows(ctx, frames, selector)
+    return frames
+
+
+def _record_table_rows(ctx: ScenarioContext, frames: list[bytes], selector: int | None) -> None:
+    for frame in frames:
+        decoded = decode_table_read_response(frame)
+        if decoded is None or selector is None:
+            continue
+        echo, value = decoded
+        row = {
+            "selector": selector,
+            "echo": echo,
+            "value": value,
+            "frame": format_frame(frame),
+        }
+        ctx.table_rows.append(row)
+        ctx.logger.event(f"TABLE selector=0x{selector:03X} echo={echo:02X} value={value:04X}")
+
+
+def _send_and_record(ctx: ScenarioContext, frame: bytes, label: str) -> None:
+    _send_frame(ctx.device, frame, ctx.logger, label)
+    ctx.tx_records.append(
+        {
+            "label": label,
+            "frame": format_frame(frame),
+            "checksum_ok": frame_checksum_ok(frame),
+        }
+    )
+
+
+def _count_target(ctx: ScenarioContext, frame: bytes) -> None:
+    text = format_frame(frame)
+    ctx.target_counts[text] = ctx.target_counts.get(text, 0) + 1
+    ctx.logger.event(f"ACK_TARGET {text} count={ctx.target_counts[text]}")
+
+
+def _selector_list(spec: dict[str, Any]) -> list[int]:
+    if "selectors" in spec:
+        raw_selectors = spec["selectors"]
+        if not isinstance(raw_selectors, list):
+            raise SystemExit("table_sweep selectors must be an array")
+        return [_int_value(selector) & 0x01FF for selector in raw_selectors]
+    start = _int_value(spec.get("start", 0))
+    count = max(0, _int_value(spec.get("count", 0x80)))
+    return [((start + offset) & 0x01FF) for offset in range(count)]
+
+
+def _parse_frame_list(raw: Any) -> set[bytes]:
+    if raw is None:
+        return set()
+    values = raw if isinstance(raw, list) else [raw]
+    return {_parse_required_frame(value) for value in values}
+
+
+def _parse_required_frame(raw: Any) -> bytes:
+    if raw is None:
+        raise SystemExit("frame is required")
+    if isinstance(raw, bytes):
+        return raw
+    if not isinstance(raw, str):
+        raise SystemExit(f"frame must be a hex string, got {raw!r}")
+    return parse_frame(raw)
+
+
+def _parse_optional_frame(raw: Any, default: bytes) -> bytes:
+    if raw is None:
+        return default
+    return _parse_required_frame(raw)
+
+
+def _int_value(raw: Any) -> int:
+    if isinstance(raw, int):
+        return raw
+    if isinstance(raw, str):
+        return int(raw, 0)
+    raise SystemExit(f"expected integer value, got {raw!r}")
+
+
+def _optional_int(raw: Any) -> int | None:
+    if raw is None:
+        return None
+    return _int_value(raw)
+
+
+def _ack_limit_reached(ctx: ScenarioContext, ack: dict[str, Any]) -> bool:
+    max_acks = ack.get("max_acks")
+    if max_acks is not None and ctx.ack_sent >= max_acks:
+        return True
+    max_target_hits = ack.get("max_target_hits")
+    if max_target_hits is not None and sum(ctx.target_counts.values()) >= max_target_hits:
+        return True
+    return False
+
+
+def _print_dry_run(args: argparse.Namespace, scenario: dict[str, Any], log_path: Path, stdout: TextIO) -> None:
+    print(f"scenario={scenario.get('name', args.scenario.stem)}", file=stdout)
+    print(f"device={args.port} {args.baud} 8N1", file=stdout)
+    print(f"relay={args.relay_port} {args.relay_baud}", file=stdout)
+    print(f"sync={args.sync}", file=stdout)
+    print(f"log={log_path}", file=stdout)
+    for index, step in enumerate(_scenario_steps(scenario), start=1):
+        action, spec = _normalize_step(step)
+        print(f"step[{index}]={action}", file=stdout)
+        if action == "send":
+            frame = _parse_required_frame(spec.get("frame"))
+            print(f"  frame={format_frame(frame)} checksum_ok={int(frame_checksum_ok(frame))}", file=stdout)
+        elif action == "table_sweep":
+            selectors = _selector_list(spec)
+            ack = _ack_config(spec.get("ack_on", {}))
+            if selectors:
+                first = selectors[0]
+                last = selectors[-1]
+                print(f"  selectors={len(selectors)} first=0x{first:03X} last=0x{last:03X}", file=stdout)
+            else:
+                print("  selectors=0", file=stdout)
+            print(f"  gap={float(spec.get('gap', 0.080)):.3f}", file=stdout)
+            for target in sorted(ack["targets"]):
+                print(f"  ack_target={format_frame(target)}", file=stdout)
+            print(f"  ack_frame={format_frame(ack['frame'])}", file=stdout)
+            print(f"  max_acks={ack['max_acks']} max_target_hits={ack['max_target_hits']}", file=stdout)
+
+
+def _emit_summary(ctx: ScenarioContext, logger: BenchLogger) -> None:
+    logger.emit()
+    logger.emit("Summary")
+    logger.emit(f"rx_frames={len(ctx.detector.frames)} trailing_unframed_bytes={len(ctx.detector.buffer)}")
+    logger.emit(f"resync_events={ctx.detector.resync_events} dropped_bytes={ctx.detector.dropped_bytes}")
+    logger.emit(f"tx_frames={len(ctx.tx_records)} ack_sent={ctx.ack_sent} table_response_rows={len(ctx.table_rows)}")
+    logger.emit(f"abort_requested={int(ctx.abort_requested)}")
+    for target, count in sorted(ctx.target_counts.items()):
+        logger.emit(f"ack_target {target}={count}")
+    for label, count in sorted(ctx.detector.labels.items()):
+        logger.emit(f"{label}={count}")
+    for row in ctx.table_rows:
+        logger.emit(
+            f"table selector=0x{row['selector']:03X} echo=0x{row['echo']:02X} value=0x{row['value']:04X}"
+        )
+
+
+def _write_result_json(path: Path, scenario: dict[str, Any], log_path: Path, ctx: ScenarioContext) -> None:
+    path.parent.mkdir(parents=True, exist_ok=True)
+    result = {
+        "scenario": scenario.get("name", ""),
+        "log": str(log_path),
+        "rx_frames": len(ctx.detector.frames),
+        "trailing_unframed_bytes": len(ctx.detector.buffer),
+        "resync_events": ctx.detector.resync_events,
+        "dropped_bytes": ctx.detector.dropped_bytes,
+        "labels": dict(ctx.detector.labels),
+        "tx_frames": ctx.tx_records,
+        "ack_sent": ctx.ack_sent,
+        "abort_requested": ctx.abort_requested,
+        "ack_targets": ctx.target_counts,
+        "table_rows": ctx.table_rows,
+    }
+    path.write_text(json.dumps(result, indent=2, sort_keys=True) + "\n", encoding="utf-8")
+
+
+__all__ = [
+    "DEFAULT_ACK_FRAME",
+    "DEFAULT_ACK_TARGET",
+    "build_arg_parser",
+    "load_scenario",
+    "main",
+]

h8536/serial_semantics.py

@@ -392,6 +392,9 @@ def _find_command_dispatch(ordered: list[JsonObject]) -> JsonObject | None:
             continue
 
         comparisons = _dispatch_comparisons(ordered, index + 1, selector_reg)
+        state_split = _dispatcher_state_split(ordered, index + 1, comparisons)
+        if state_split:
+            _annotate_dispatch_comparison_availability(comparisons, state_split)
         command_values = sorted({int(item["command_value"]) for item in comparisons})
         candidate = {
             "kind": "command_dispatch_candidate",
@@ -413,6 +416,8 @@ def _find_command_dispatch(ordered: list[JsonObject]) -> JsonObject | None:
             "command_values": command_values,
             "command_values_hex": [_h16(value, width=2) for value in command_values],
             "comparisons": comparisons,
+            "state_split": state_split,
+            "dispatcher_split": state_split,
             "cases": [
                 {
                     "value": int(item["command_value"]),
@@ -421,6 +426,8 @@ def _find_command_dispatch(ordered: list[JsonObject]) -> JsonObject | None:
                     "target_hex": item["handler_start_hex"],
                     "compare_address": item["compare_address"],
                     "branch_address": item["branch_address"],
+                    "availability": item.get("availability"),
+                    "availability_conditions": item.get("availability_conditions", []),
                 }
                 for item in comparisons
             ],
@@ -446,6 +453,101 @@ def _find_command_dispatch(ordered: list[JsonObject]) -> JsonObject | None:
     return best
 
 
+def _dispatcher_state_split(
+    ordered: list[JsonObject],
+    start_index: int,
+    comparisons: list[JsonObject],
+) -> JsonObject | None:
+    if not comparisons:
+        return None
+    for index in range(start_index, min(len(ordered) - 1, start_index + 24)):
+        ins = ordered[index]
+        if not _has_ref_in_range(ins, 0xFAA2, 0xFAA2):
+            continue
+        if _mnemonic_root(str(ins.get("mnemonic", ""))) != "TST":
+            continue
+        branch = ordered[index + 1]
+        if _mnemonic_root(str(branch.get("mnemonic", ""))) != "BNE":
+            continue
+        targets = _targets(branch)
+        if not targets:
+            continue
+        continuation_start = int(targets[0])
+        initial_values = sorted(
+            {
+                int(item["command_value"])
+                for item in comparisons
+                if int(item.get("compare_address", 0)) < continuation_start
+            }
+        )
+        continuation_values = sorted(
+            {
+                int(item["command_value"])
+                for item in comparisons
+                if int(item.get("compare_address", 0)) >= continuation_start
+            }
+        )
+        if not initial_values and not continuation_values:
+            continue
+        return {
+            "kind": "serial_command_dispatch_state_split",
+            "state_address": 0xFAA2,
+            "state_address_hex": _h16(0xFAA2),
+            "test_address": int(ins["address"]),
+            "test_address_hex": _h16(int(ins["address"])),
+            "branch_address": int(branch["address"]),
+            "branch_address_hex": _h16(int(branch["address"])),
+            "continuation_target": continuation_start,
+            "continuation_target_hex": _h16(continuation_start),
+            "initial_idle_commands": initial_values,
+            "initial_idle_commands_hex": [_h16(value, width=2) for value in initial_values],
+            "continuation_commands": continuation_values,
+            "continuation_commands_hex": [_h16(value, width=2) for value in continuation_values],
+            "summary": (
+                "FAA2 == 0 takes the initial/idle dispatcher path; FAA2 != 0 takes "
+                "the continuation dispatcher path."
+            ),
+            "caveat": (
+                "Initial dispatch follows checksum validation and RX error handling. Command 1 "
+                "is only on the initial/idle path and is also gated by F861.bit7 == 0."
+            ),
+            "evidence_addresses": [int(ins["address"]), int(branch["address"])],
+            "evidence_addresses_hex": _hlist([int(ins["address"]), int(branch["address"])]),
+        }
+    return None
+
+
+def _annotate_dispatch_comparison_availability(
+    comparisons: list[JsonObject],
+    state_split: Mapping[str, Any],
+) -> None:
+    continuation_start = state_split.get("continuation_target")
+    if not isinstance(continuation_start, int):
+        return
+    for item in comparisons:
+        compare_address = item.get("compare_address")
+        if not isinstance(compare_address, int):
+            continue
+        command_value = int(item.get("command_value", -1))
+        if compare_address < continuation_start:
+            availability = "initial_idle_dispatch"
+            conditions = [
+                "valid checksum/no RX physical error",
+                "FAA2 == 0",
+            ]
+            if command_value == 0x01:
+                conditions.append("F861.bit7 == 0")
+        else:
+            availability = "continuation_dispatch"
+            conditions = [
+                "valid checksum/no RX physical error",
+                "FAA2 != 0",
+            ]
+        item["availability"] = availability
+        item["availability_conditions"] = conditions
+        item["availability_summary"] = " && ".join(conditions)
+
+
 def _dispatch_comparisons(
     ordered: list[JsonObject],
     start_index: int,
@@ -537,6 +639,8 @@ def _command_candidates(
             "dispatch_compare_address_hex": comparison["compare_address_hex"],
             "dispatch_branch_address": comparison["branch_address"],
             "dispatch_branch_address_hex": comparison["branch_address_hex"],
+            "availability": comparison.get("availability"),
+            "availability_conditions": comparison.get("availability_conditions", []),
         }
         if alternative not in command["handler_alternatives"]:
             command["handler_alternatives"].append(alternative)
@@ -555,6 +659,30 @@ def _command_candidates(
         command["handler_start_hex"] = _h16(starts_for_command[0]) if len(starts_for_command) == 1 else None
         command["handler_end"] = ends_for_command[0] if len(ends_for_command) == 1 else None
         command["handler_end_hex"] = _h16(ends_for_command[0]) if len(ends_for_command) == 1 else None
+        availability_conditions = _dedupe_strings(
+            str(condition)
+            for alt in alternatives
+            for condition in alt.get("availability_conditions", [])
+            if condition
+        )
+        availability = _dedupe_strings(
+            str(alt["availability"])
+            for alt in alternatives
+            if alt.get("availability")
+        )
+        availability_summaries = _dedupe_strings(
+            " && ".join(str(condition) for condition in alt.get("availability_conditions", []) if condition)
+            for alt in alternatives
+            if alt.get("availability_conditions")
+        )
+        command["availability"] = availability[0] if len(availability) == 1 else availability
+        command["availability_conditions"] = availability_conditions
+        command["availability_summary"] = (
+            availability_summaries[0]
+            if len(availability_summaries) == 1
+            else " OR ".join(availability_summaries)
+        )
+        command["semantic_notes"] = _command_semantic_notes(int(command["command_value"]))
 
         ranges_for_command = [
             (alt["handler_start"], alt["handler_end"])
@@ -657,26 +785,47 @@ def _command_name_candidate(value: int) -> str:
 def _command_summary(value: int) -> str:
     return {
         0x00: "candidate write of RX[3:4] into primary/current tables, followed by a response",
-        0x01: "candidate read from the primary table, followed by a response carrying the value",
+        0x01: "initial/idle-path primary table read only, followed by an odd response staging sequence",
         0x02: "candidate clear/abort path with no immediate response builder",
         0x04: "candidate write/update path that stores a value without an immediate serial response",
-        0x05: "candidate pending/event acknowledgement path",
+        0x05: "continuation-only conditional acknowledgement/session clear path",
         0x06: "candidate secondary-table value write path",
-        0x07: "candidate retransmit/NAK-style path; error handling also builds command 0x07 responses",
+        0x07: "candidate retransmit path; retry/error handling also builds a command 0x07 RX-payload echo",
     }.get(value, "candidate command semantics are unknown")
 
 
+def _command_semantic_notes(value: int) -> list[str]:
+    return {
+        0x01: [
+            "Only accepted on the initial/idle dispatcher path: valid checksum/no RX error, FAA2 == 0, and F861.bit7 == 0.",
+            "BCD7 stages F850=0x04, writes F851 from F861 and then overwrites F851 from F862.",
+            "BCD7 reads the primary table word at E000 + 2*selector; F854 receives the low byte and F853 receives the high byte.",
+            "F852 is not freshly written in the BCD7 handler, so do not describe the response as a fixed 04 00 QQ hi lo frame.",
+        ],
+        0x05: [
+            "Only accepted on the continuation dispatcher path when FAA2 != 0.",
+            "For selector 0x0040, frame 05 00 40 00 00 1F performs no response staging.",
+            "The handler clears FAA3/FAA2; F9B5 advances only when FAA2.bit3 was set from a queued report.",
+            "If FAA2 == 0, command 5 falls through the initial dispatcher instead of doing acknowledgement work.",
+        ],
+        0x07: [
+            "loc_BE4D is a retry/error echo path: F850=0x07 and F861-F864 are copied into F851-F854 before loc_BA26.",
+            "Observed frame 07 80 40 20 90 2D means RX bytes F861-F864 were 80 40 20 90; it is not a table value.",
+        ],
+    }.get(value, [])
+
+
 def _command_effect_summary(value: int, effects: list[JsonObject]) -> str:
     if not effects:
         return "No structured command effects were inferred."
     return {
         0x00: "Candidate acknowledged set: writes value bytes to primary/current tables, flags the index, and stages an echo-style response.",
-        0x01: "Candidate read: reads the primary table and stages a value response.",
+        0x01: "Initial/idle candidate read: reads the primary table and stages an odd value response with F852 possibly stale.",
         0x02: "Candidate clear/abort: clears serial session state without an observed immediate response.",
         0x04: "Candidate deferred set: writes value bytes and flags the index without an observed immediate response.",
-        0x05: "Candidate acknowledgement/clear: updates pending/event state without an observed immediate response.",
+        0x05: "Continuation-only ACK/session clear: clears FAA3/FAA2 and only advances F9B5 when queued-report FAA2.bit3 was set; selector 0x0040 has no response.",
         0x06: "Candidate secondary set: writes value bytes to the secondary table and flags the index.",
-        0x07: "Candidate retransmit/error reply: reuses prior TX bytes or builds an explicit 0x07 retry/error response.",
+        0x07: "Candidate retransmit/error reply: reuses prior TX bytes or copies RX payload bytes behind an explicit 0x07 retry/error echo.",
     }.get(value, "Candidate effects are inferred from handler-local writes, reads, calls, and response staging.")
 
 
@@ -740,9 +889,10 @@ def _command_effects(
             {
                 "kind": "table_read_candidate",
                 "target_candidate": "primary_value_table_candidate",
-                "destination_candidate": "response value bytes",
+                "destination_candidate": "response value bytes F854/F853, with F852 not freshly written by BCD7",
                 "table_base": 0xE000,
                 "table_base_hex": _h16(0xE000),
+                "address_expression_candidate": "E000 + 2*selector",
                 "evidence_addresses": _table_access_addresses(table_accesses, 0x2000, "read"),
             }
         )
@@ -781,9 +931,15 @@ def _command_effects(
     elif value == 0x05:
         add(
             {
-                "kind": "pending_acknowledgement_candidate",
+                "kind": "conditional_ack_session_clear_candidate",
                 "target_candidate": "selected event/pending state",
-                "operation_candidate": "clear selected pending flags and then clear serial session state",
+                "operation_candidate": (
+                    "when FAA2 != 0, clear FAA3/FAA2; advance F9B5 only if FAA2.bit3 was "
+                    "set from queued-report state; selector 0x0040 stages no response"
+                ),
+                "selector_without_response_hex": _h16(0x0040),
+                "requires": ["FAA2 != 0"],
+                "fallthrough_when": "FAA2 == 0",
                 "evidence_addresses": _dedupe_ints(
                     _state_access_addresses(state_accesses, 0xFAA2)
                     + _state_access_addresses(state_accesses, 0xFAA3)
@@ -822,6 +978,16 @@ def _command_effects(
                 "evidence_addresses": _addresses_in_ranges(ordered, ranges, 0xBE05, 0xBE22),
             }
         )
+        add(
+            {
+                "kind": "retry_error_echo_candidate",
+                "source_candidate": "RX payload bytes F861-F864",
+                "destination_candidate": "F850=0x07, F851-F854=F861-F864 before loc_BA26",
+                "observed_frame_caveat": "07 80 40 20 90 2D echoes RX payload 80 40 20 90; it is not a table value",
+                "response_candidates": [item for item in response_ids if item == "response_at_BE6A"],
+                "evidence_addresses": _addresses_in_ranges(ordered, ranges, 0xBE4D, 0xBE6A),
+            }
+        )
 
     if response_ids:
         add(
@@ -852,6 +1018,10 @@ def _command_effect_aliases(commands: list[JsonObject]) -> list[JsonObject]:
                 "command_value_hex": command.get("command_value_hex"),
                 "name_candidate": command.get("name_candidate"),
                 "summary": command.get("effect_summary", command.get("summary")),
+                "availability": command.get("availability"),
+                "availability_conditions": command.get("availability_conditions", []),
+                "availability_summary": command.get("availability_summary"),
+                "semantic_notes": command.get("semantic_notes", []),
                 "effects": command.get("effects", []),
                 "response_candidates": command.get("response_candidates", []),
                 "evidence_addresses": command.get("evidence_addresses", []),
@@ -938,6 +1108,7 @@ def _response_candidates(ordered: list[JsonObject]) -> list[JsonObject]:
         }
         response["schema"] = _response_schema(response)
         response["byte_schema"] = response["schema"]["bytes"]
+        response["semantic_notes"] = response["schema"].get("semantic_notes", [])
         responses.append(response)
     return responses
 
@@ -1004,6 +1175,7 @@ def _response_schema(response: Mapping[str, Any]) -> JsonObject:
         for addr in item.get("evidence_addresses", [])
         if isinstance(addr, int)
     )
+    semantic_notes = _response_schema_semantic_notes(response, bytes_out)
     return {
         "kind": "response_schema_candidate",
         "response_id": response.get("id"),
@@ -1014,6 +1186,7 @@ def _response_schema(response: Mapping[str, Any]) -> JsonObject:
         "buffer_end": TX_STAGING_END,
         "buffer_end_hex": _h16(TX_STAGING_END),
         "bytes": bytes_out,
+        "semantic_notes": semantic_notes,
         "evidence_addresses": evidence_addresses,
         "evidence_addresses_hex": _hlist(evidence_addresses),
         "confidence": "candidate-medium" if evidence_addresses else "candidate-low",
@@ -1024,6 +1197,30 @@ def _response_schema(response: Mapping[str, Any]) -> JsonObject:
     }
 
 
+def _response_schema_semantic_notes(
+    response: Mapping[str, Any],
+    bytes_out: list[JsonObject],
+) -> list[str]:
+    call_address = response.get("call_address")
+    if call_address == 0xBCFA:
+        for item in bytes_out:
+            if item.get("offset") == 2 and item.get("source_kind") == "unknown":
+                item["source_kind"] = "stale_or_unchanged"
+                item["source_expression"] = "stale/unchanged"
+                item["caveat"] = "BCD7 does not freshly write F852 before loc_BA26."
+        return [
+            "Command 1 BCD7 staging is odd: F850=0x04; F851 is written from F861 then overwritten by F862.",
+            "The primary table word is read from E000 + 2*selector; F854/F853 receive low/high value bytes.",
+            "F852 may be stale or unchanged in this handler; avoid a fixed 04 00 QQ hi lo response shape.",
+        ]
+    if call_address == 0xBE6A:
+        return [
+            "loc_BE4D retry/error echo stages F850=0x07 and copies F861-F864 into F851-F854 before loc_BA26.",
+            "Observed 07 80 40 20 90 2D echoes RX payload bytes 80 40 20 90; it is not a table-derived value.",
+        ]
+    return []
+
+
 def _response_schemas(responses: list[JsonObject]) -> list[JsonObject]:
     return [
         response["schema"]
@@ -1203,6 +1400,7 @@ def _response_builder_aliases(responses: list[JsonObject]) -> list[JsonObject]:
                 "call_address": response.get("call_address"),
                 "call_address_hex": response.get("call_address_hex"),
                 "writes": writes,
+                "semantic_notes": response.get("semantic_notes", []),
                 "evidence_addresses": response.get("evidence_addresses", []),
                 "evidence_addresses_hex": response.get("evidence_addresses_hex", []),
                 "confidence": response.get("confidence", "medium"),
@@ -1571,6 +1769,7 @@ def _retry_error_model(ordered: list[JsonObject], responses: list[JsonObject]) -
     retry_evidence = _dedupe_ints(
         [int(ins["address"]) for ins in retry_path if _has_ref_in_range(ins, 0xFAA2, 0xFAA6)]
         + [int(ins["address"]) for ins in retry_path if _has_ref_in_range(ins, TX_STAGING_START, TX_STAGING_END)]
+        + [int(ins["address"]) for ins in retry_path if _has_ref_in_range(ins, RX_FRAME_START + 1, RX_FRAME_START + 4)]
         + [int(ins["address"]) for ins in retry_path if _is_send_builder_call(ins)]
         + _response_evidence_addresses(responses, checksum_error_response)
     )
@@ -1606,8 +1805,16 @@ def _retry_error_model(ordered: list[JsonObject], responses: list[JsonObject]) -
             "response_candidates": checksum_error_response,
             "summary": (
                 "Candidate retry path clears/consults serial flags, increments FAA6, compares it "
-                "with 2, and when still below the apparent limit stages a command 0x07 response."
+                "with 2, and when still below the apparent limit enters loc_BE4D to stage a "
+                "command 0x07 retry/error echo of RX payload bytes F861-F864."
             ),
+            "echo_response_candidate": {
+                "entry_label": "loc_BE4D",
+                "entry_address": 0xBE4D,
+                "entry_address_hex": _h16(0xBE4D),
+                "staging_candidate": "F850=0x07; F851-F854=F861-F864",
+                "observed_frame_caveat": "07 80 40 20 90 2D echoes RX payload 80 40 20 90 and is not a table value.",
+            },
             "evidence_addresses": retry_evidence,
             "evidence_addresses_hex": _hlist(retry_evidence),
             "confidence": "candidate-medium" if retry_counter_evidence else "candidate-low",
@@ -1646,7 +1853,7 @@ def _gate_queue_model(ordered: list[JsonObject], commands: list[JsonObject]) ->
     command_ack_values = [
         int(command["command_value"])
         for command in commands
-        if command.get("command_value") in {0x05, 0x06}
+        if command.get("command_value") == 0x05
     ]
     if not evidence and not command_ack_values:
         return None
@@ -1774,13 +1981,18 @@ def _gate_queue_model(ordered: list[JsonObject], commands: list[JsonObject]) ->
             },
             {
                 "name": "host_ack_can_advance_queue",
-                "summary": "Commands 0x05/0x06 are modeled as acknowledgement paths that can clear pending state or advance F9B5.",
+                "summary": (
+                    "Command 0x05 is a continuation-only ACK/session clear path: it clears "
+                    "FAA3/FAA2 and advances F9B5 only when queued-report FAA2.bit3 was set. "
+                    "Selector 0x0040 has no response; if FAA2 == 0 the command falls through "
+                    "instead of doing ACK work."
+                ),
                 "command_values_hex": [_h16(value, width=2) for value in command_ack_values],
-                "state_addresses_hex": [_h16(0xF9B5)],
+                "state_addresses_hex": [_h16(0xFAA2), _h16(0xFAA3), _h16(0xF9B5)],
                 "evidence_addresses": _dedupe_ints(
                     addr
                     for command in commands
-                    if command.get("command_value") in {0x05, 0x06}
+                    if command.get("command_value") == 0x05
                     for addr in command.get("evidence_addresses", [])
                     if isinstance(addr, int)
                 ),
@@ -2283,9 +2495,26 @@ def _response_window(ordered: list[JsonObject], call_index: int) -> list[JsonObj
     for index in range(call_index - 1, max(-1, call_index - 48), -1):
         candidate = ordered[index]
         mnemonic = str(candidate.get("mnemonic", "")).upper()
-        if mnemonic in {"RTS", "RTE"}:
+        root = _mnemonic_root(mnemonic)
+        if root in {"RTS", "RTE"}:
             break
-        if candidate.get("kind") == "branch" and mnemonic != "BSR":
+        if root in {
+            "BRA",
+            "BEQ",
+            "BNE",
+            "BCS",
+            "BCC",
+            "BHI",
+            "BLS",
+            "BGE",
+            "BLT",
+            "BGT",
+            "BLE",
+            "BMI",
+            "BPL",
+            "BVS",
+            "BVC",
+        }:
             break
         start = index
     return ordered[start:call_index]

h8536/serial_table_dump.py

@@ -185,6 +185,7 @@ def _summary(
     logger.emit()
     logger.emit("Summary")
     logger.emit(f"rx_frames={len(detector.frames)} table_response_rows={len(table_rows)}")
+    logger.emit(f"trailing_unframed_bytes={len(detector.buffer)} resync_events={detector.resync_events} dropped_bytes={detector.dropped_bytes}")
     for selector, value in table_rows:
         logger.emit(f"table selector=0x{selector:03X} value=0x{value:04X}")
 

scenarios/ack-race-000-001.json

@@ -0,0 +1,48 @@
+{
+  "name": "ack-race-000-001",
+  "notes": [
+    "Focused command-1 pair that has produced the 07 80 40 20 90 2D retry frame on the bench.",
+    "Uses immediate reactive ACK with a 2 ms poll interval to test whether command 5 can beat the second retry."
+  ],
+  "steps": [
+    {
+      "action": "power_cycle",
+      "off_seconds": 1.5
+    },
+    {
+      "action": "wait_ready",
+      "timeout": 10.0,
+      "heartbeats": 2,
+      "require": true
+    },
+    {
+      "action": "drain",
+      "seconds": 0.25
+    },
+    {
+      "action": "table_sweep",
+      "selectors": [
+        "0x000",
+        "0x001"
+      ],
+      "gap": 1.0,
+      "ack_on": {
+        "frames": [
+          "07 80 40 20 90 2D"
+        ],
+        "ack_frame": "05 00 40 00 00 1F",
+        "ack_guard": 0.0,
+        "poll_interval": 0.002,
+        "post_ack_read": 1.0,
+        "once_per_selector": true,
+        "max_acks": 4,
+        "max_target_hits": 8,
+        "abort_on_limit": true
+      }
+    },
+    {
+      "action": "listen",
+      "seconds": 2.0
+    }
+  ]
+}

scenarios/early-ack-000-001.json

@@ -0,0 +1,41 @@
+{
+  "name": "early-ack-000-001",
+  "notes": [
+    "Manual early-ACK variant: send the command-1 pair and immediately send command-5 ACK instead of waiting for the retry frame.",
+    "This tests whether the ACK has to arrive before the ROM emits the second retry."
+  ],
+  "steps": [
+    {
+      "action": "power_cycle",
+      "off_seconds": 1.5
+    },
+    {
+      "action": "wait_ready",
+      "timeout": 10.0,
+      "heartbeats": 2,
+      "require": true
+    },
+    {
+      "action": "drain",
+      "seconds": 0.25
+    },
+    {
+      "action": "send",
+      "label": "read_0x000",
+      "frame": "01 00 00 00 00 5B",
+      "listen": 0.75
+    },
+    {
+      "action": "send",
+      "label": "read_0x001",
+      "frame": "01 00 01 00 00 5A",
+      "listen": 0.0
+    },
+    {
+      "action": "send",
+      "label": "early_ack",
+      "frame": "05 00 40 00 00 1F",
+      "listen": 2.0
+    }
+  ]
+}

scenarios/table-sweep-ack-000-07f.json

@@ -0,0 +1,46 @@
+{
+  "name": "table-sweep-ack-000-07f",
+  "notes": [
+    "Read-only command-1 sweep of live E000 table selectors 0x000-0x07F.",
+    "If the visible retry frame 07 80 40 20 90 2D appears, send command-5 ACK 05 00 40 00 00 1F."
+  ],
+  "steps": [
+    {
+      "action": "power_cycle",
+      "off_seconds": 1.5
+    },
+    {
+      "action": "wait_ready",
+      "timeout": 10.0,
+      "heartbeats": 2,
+      "require": true
+    },
+    {
+      "action": "drain",
+      "seconds": 0.25
+    },
+    {
+      "action": "table_sweep",
+      "start": "0x000",
+      "count": "0x080",
+      "gap": 0.75,
+      "ack_on": {
+        "frames": [
+          "07 80 40 20 90 2D"
+        ],
+        "ack_frame": "05 00 40 00 00 1F",
+        "ack_guard": 0.0,
+        "poll_interval": 0.002,
+        "post_ack_read": 0.35,
+        "once_per_selector": true,
+        "max_acks": 8,
+        "max_target_hits": 32,
+        "abort_on_limit": true
+      }
+    },
+    {
+      "action": "listen",
+      "seconds": 2.0
+    }
+  ]
+}

scripts/serial_scenario.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+"""Run JSON-described serial bench scenarios."""
+
+import sys
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+if str(ROOT) not in sys.path:
+    sys.path.insert(0, str(ROOT))
+
+from h8536.serial_scenario import main
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

tests/test_bench_connect_lcd.py

@@ -43,9 +43,34 @@ class BenchConnectLcdTest(unittest.TestCase):
             ],
         )
 
+    def test_detector_resyncs_to_checksum_valid_frame(self):
+        detector = FrameDetector()
+
+        detected = detector.feed(bytes.fromhex("FF0000000080DA"))
+
+        self.assertEqual([(format_frame(frame), label) for frame, label in detected], [
+            ("00 00 00 00 80 DA", "heartbeat")
+        ])
+        self.assertEqual(detector.dropped_bytes, 1)
+        self.assertEqual(detector.resync_events, 1)
+
+    def test_detector_prefers_labeled_heartbeat_over_shifted_valid_window(self):
+        detector = FrameDetector()
+        heartbeat = bytes.fromhex("0000000080DA")
+
+        detected = detector.feed(heartbeat[1:] + heartbeat)
+
+        self.assertEqual([(format_frame(frame), label) for frame, label in detected], [
+            ("00 00 00 00 80 DA", "heartbeat")
+        ])
+        self.assertEqual(detector.dropped_bytes, 5)
+
     def test_label_frame_marks_unlabeled_checksum_ok_frame(self):
         self.assertEqual(label_frame(bytes.fromhex("01000000005B")), "checksum_ok_unlabeled")
 
+    def test_label_frame_marks_table_readback_candidate(self):
+        self.assertEqual(label_frame(bytes.fromhex("04001280804C")), "table_readback_candidate")
+
     def test_label_frame_marks_real_bench_c0_6020_response(self):
         self.assertEqual(label_frame(bytes.fromhex("0780C060205D")), "visible_C0_6020_family_candidate")
 

tests/test_serial_pseudocode.py

@@ -196,6 +196,60 @@ class SerialPseudocodeTest(unittest.TestCase):
         self.assertIn("case 0x01u:", text)
         self.assertIn("candidate_read_value(logical_index, value);", text)
 
+    def test_protocol_pseudocode_surfaces_dispatcher_split(self):
+        payload = candidate_payload()
+        payload["instructions"] = [
+            {"address": 0xBC08, "mnemonic": "MOV:G.B", "operands": "@H'F860, R0", "references": [{"address": 0xF860}], "targets": []},
+            {"address": 0xBC0C, "mnemonic": "AND.B", "operands": "#H'07, R0", "references": [], "targets": []},
+            {"address": 0xBC0F, "mnemonic": "TST.B", "operands": "@H'FAA2", "references": [{"address": 0xFAA2}], "targets": []},
+            {"address": 0xBC13, "mnemonic": "BNE", "operands": "loc_BC3A", "references": [], "targets": [0xBC3A]},
+            {"address": 0xBC19, "mnemonic": "BTST.B", "operands": "#7, @H'F861", "references": [{"address": 0xF861}], "targets": []},
+            {"address": 0xBC20, "mnemonic": "CMP:E", "operands": "#H'00, R0", "references": [], "targets": []},
+            {"address": 0xBC22, "mnemonic": "BEQ", "operands": "loc_BC69", "references": [], "targets": [0xBC69]},
+            {"address": 0xBC24, "mnemonic": "CMP:E", "operands": "#H'01, R0", "references": [], "targets": []},
+            {"address": 0xBC26, "mnemonic": "BEQ", "operands": "loc_BCD7", "references": [], "targets": [0xBCD7]},
+            {"address": 0xBC29, "mnemonic": "CMP:E", "operands": "#H'02, R0", "references": [], "targets": []},
+            {"address": 0xBC2B, "mnemonic": "BEQ", "operands": "loc_BD04", "references": [], "targets": [0xBD04]},
+            {"address": 0xBC2E, "mnemonic": "CMP:E", "operands": "#H'07, R0", "references": [], "targets": []},
+            {"address": 0xBC30, "mnemonic": "BEQ", "operands": "loc_BE05", "references": [], "targets": [0xBE05]},
+            {"address": 0xBC45, "mnemonic": "CMP:E", "operands": "#H'04, R0", "references": [], "targets": []},
+            {"address": 0xBC47, "mnemonic": "BEQ", "operands": "loc_BD0E", "references": [], "targets": [0xBD0E]},
+            {"address": 0xBC4A, "mnemonic": "CMP:E", "operands": "#H'05, R0", "references": [], "targets": []},
+            {"address": 0xBC4C, "mnemonic": "BEQ", "operands": "loc_BD80", "references": [], "targets": [0xBD80]},
+            {"address": 0xBC4F, "mnemonic": "CMP:E", "operands": "#H'06, R0", "references": [], "targets": []},
+            {"address": 0xBC51, "mnemonic": "BEQ", "operands": "loc_BDDB", "references": [], "targets": [0xBDDB]},
+            {"address": 0xBC54, "mnemonic": "CMP:E", "operands": "#H'07, R0", "references": [], "targets": []},
+            {"address": 0xBC56, "mnemonic": "BEQ", "operands": "loc_BE05", "references": [], "targets": [0xBE05]},
+        ]
+
+        text = generate_serial_pseudocode(payload)
+
+        self.assertIn("dispatcher split: FAA2 == 0 accepts initial/idle commands H'00, H'01, H'02, H'07; FAA2 != 0 accepts continuation commands H'04, H'05, H'06, H'07", text)
+        self.assertIn("bool session_active = MEM8[0xFAA2u] != 0u;", text)
+        self.assertIn("Initial/idle dispatcher", text)
+        self.assertIn("Continuation dispatcher", text)
+        self.assertIn("availability: valid checksum/no RX physical error && FAA2 == 0 && F861.bit7 == 0", text)
+
+    def test_protocol_pseudocode_surfaces_retry_echo_schema(self):
+        payload = candidate_payload()
+        payload["instructions"] = [
+            {"address": 0xBE4B, "mnemonic": "BRA", "operands": "loc_BE6D", "references": [], "targets": [0xBE6D]},
+            {"address": 0xBE4D, "mnemonic": "MOV:G.B", "operands": "#H'07, @H'F850", "references": [{"address": 0xF850}], "targets": []},
+            {"address": 0xBE52, "mnemonic": "MOV:G.B", "operands": "@H'F861, R0", "references": [{"address": 0xF861}], "targets": []},
+            {"address": 0xBE56, "mnemonic": "MOV:G.B", "operands": "R0, @H'F851", "references": [{"address": 0xF851}], "targets": []},
+            {"address": 0xBE5A, "mnemonic": "MOV:G.W", "operands": "@H'F862, R0", "references": [{"address": 0xF862}], "targets": []},
+            {"address": 0xBE5E, "mnemonic": "MOV:G.W", "operands": "R0, @H'F852", "references": [{"address": 0xF852}], "targets": []},
+            {"address": 0xBE62, "mnemonic": "MOV:G.B", "operands": "@H'F864, R0", "references": [{"address": 0xF864}], "targets": []},
+            {"address": 0xBE66, "mnemonic": "MOV:G.B", "operands": "R0, @H'F854", "references": [{"address": 0xF854}], "targets": []},
+            {"address": 0xBE6A, "mnemonic": "BSR", "operands": "loc_BA26", "references": [], "targets": [0xBA26]},
+        ]
+
+        text = generate_serial_pseudocode(payload)
+
+        self.assertIn("response_at_BE6A: byte0=0x07; byte1=rx[1]; byte2=rx[2]; byte3=rx[3]; byte4=rx[4]", text)
+        self.assertIn("Observed 07 80 40 20 90 2D echoes RX payload bytes 80 40 20 90", text)
+        self.assertIn("not a table-derived value", text)
+
     def test_surfaces_refined_semantic_candidates(self):
         analysis = {
             "protocol_semantics": [

tests/test_serial_scenario.py

@@ -0,0 +1,50 @@
+import io
+import json
+import tempfile
+import unittest
+from pathlib import Path
+
+from h8536.serial_scenario import DEFAULT_ACK_FRAME, DEFAULT_ACK_TARGET, main
+
+
+class SerialScenarioTest(unittest.TestCase):
+    def test_dry_run_summarizes_ack_aware_table_sweep(self):
+        scenario = {
+            "name": "unit-sweep",
+            "steps": [
+                {
+                    "action": "table_sweep",
+                    "start": "0x000",
+                    "count": "0x002",
+                    "gap": 0.75,
+                    "ack_on": {
+                        "frames": ["07 80 40 20 90 2D"],
+                        "ack_frame": "05 00 40 00 00 1F",
+                        "max_acks": 8,
+                        "max_target_hits": 32,
+                    },
+                }
+            ],
+        }
+        with tempfile.TemporaryDirectory() as tmpdir:
+            path = Path(tmpdir) / "scenario.json"
+            path.write_text(json.dumps(scenario), encoding="utf-8")
+            stdout = io.StringIO()
+
+            exit_code = main([str(path), "--dry-run"], stdout=stdout)
+
+        output = stdout.getvalue()
+        self.assertEqual(exit_code, 0)
+        self.assertIn("scenario=unit-sweep", output)
+        self.assertIn("selectors=2 first=0x000 last=0x001", output)
+        self.assertIn("ack_target=07 80 40 20 90 2D", output)
+        self.assertIn("ack_frame=05 00 40 00 00 1F", output)
+        self.assertIn("max_acks=8 max_target_hits=32", output)
+
+    def test_default_ack_frames_match_current_rom_probe_candidate(self):
+        self.assertEqual(DEFAULT_ACK_TARGET, bytes.fromhex("07804020902D"))
+        self.assertEqual(DEFAULT_ACK_FRAME, bytes.fromhex("05004000001F"))
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/test_serial_semantics.py

@@ -288,6 +288,8 @@ class SerialSemanticsTest(unittest.TestCase):
         command_1_text = semantic_text(command_1)
         self.assertIn("read", command_1_text)
         self.assertIn("response", command_1_text)
+        self.assertIn("initial/idle", command_1_text)
+        self.assertIn("f852", command_1_text)
 
         command_6 = command_item(effects, 0x06)
         self.assertIsNotNone(command_6)
@@ -295,6 +297,13 @@ class SerialSemanticsTest(unittest.TestCase):
         self.assertIn("write", command_6_text)
         self.assertIn("secondary_value_table", command_6_text)
 
+        command_5 = command_item(effects, 0x05)
+        self.assertIsNotNone(command_5)
+        command_5_text = semantic_text(command_5)
+        self.assertIn("faa2 != 0", command_5_text)
+        self.assertIn("0040", command_5_text)
+        self.assertIn("no response", command_5_text)
+
     def test_planned_response_schema_tracks_immediates_and_rx_copies(self):
         semantics = only_semantics(self, planned_semantics_payload())
 
@@ -391,10 +400,105 @@ class SerialSemanticsTest(unittest.TestCase):
         self.assertIn("be9e", gate_text)
         self.assertIn("bed5", gate_text)
         self.assertIn("f9c5", gate_text)
-        self.assertIn("commands 0x05", gate_text)
+        self.assertIn("command 0x05", gate_text)
-        self.assertIn("0x06", gate_text)
+        self.assertIn("selector 0x0040 has no response", gate_text)
+        self.assertIn("faa2 == 0", gate_text)
         self.assertIn("not rom constants", gate_text)
 
+    def test_actual_dispatch_split_marks_initial_and_continuation_commands(self):
+        semantics = only_semantics(
+            self,
+            base_payload(
+                [
+                    instruction(0xBC08, "MOV:G.B", "@H'F860, R0", [0xF860]),
+                    instruction(0xBC0C, "AND.B", "#H'07, R0"),
+                    instruction(0xBC0F, "TST.B", "@H'FAA2", [0xFAA2]),
+                    instruction(0xBC13, "BNE", "loc_BC3A", targets=[0xBC3A]),
+                    instruction(0xBC19, "BTST.B", "#7, @H'F861", [0xF861]),
+                    instruction(0xBC20, "CMP:E", "#H'00, R0"),
+                    instruction(0xBC22, "BEQ", "loc_BC69", targets=[0xBC69]),
+                    instruction(0xBC24, "CMP:E", "#H'01, R0"),
+                    instruction(0xBC26, "BEQ", "loc_BCD7", targets=[0xBCD7]),
+                    instruction(0xBC29, "CMP:E", "#H'02, R0"),
+                    instruction(0xBC2B, "BEQ", "loc_BD04", targets=[0xBD04]),
+                    instruction(0xBC2E, "CMP:E", "#H'07, R0"),
+                    instruction(0xBC30, "BEQ", "loc_BE05", targets=[0xBE05]),
+                    instruction(0xBC45, "CMP:E", "#H'04, R0"),
+                    instruction(0xBC47, "BEQ", "loc_BD0E", targets=[0xBD0E]),
+                    instruction(0xBC4A, "CMP:E", "#H'05, R0"),
+                    instruction(0xBC4C, "BEQ", "loc_BD80", targets=[0xBD80]),
+                    instruction(0xBC4F, "CMP:E", "#H'06, R0"),
+                    instruction(0xBC51, "BEQ", "loc_BDDB", targets=[0xBDDB]),
+                    instruction(0xBC54, "CMP:E", "#H'07, R0"),
+                    instruction(0xBC56, "BEQ", "loc_BE05", targets=[0xBE05]),
+                ]
+            ),
+        )
+
+        split = semantics["command_dispatch"]["state_split"]
+        self.assertEqual(split["initial_idle_commands"], [0, 1, 2, 7])
+        self.assertEqual(split["continuation_commands"], [4, 5, 6, 7])
+
+        command_1 = command_item(semantics["commands"], 0x01)
+        self.assertIn("FAA2 == 0", command_1["availability_conditions"])
+        self.assertIn("F861.bit7 == 0", command_1["availability_conditions"])
+
+        command_5 = command_item(semantics["commands"], 0x05)
+        self.assertIn("FAA2 != 0", command_5["availability_conditions"])
+
+    def test_actual_bcd7_command1_response_marks_f852_stale(self):
+        semantics = only_semantics(
+            self,
+            base_payload(
+                [
+                    instruction(0xBCD4, "BRA", "loc_BE6F", targets=[0xBE6F]),
+                    instruction(0xBCD7, "MOV:G.B", "#H'04, @H'F850", [0xF850]),
+                    instruction(0xBCDC, "MOV:G.B", "@H'F861, R0", [0xF861]),
+                    instruction(0xBCE0, "MOV:G.B", "R0, @H'F851", [0xF851]),
+                    instruction(0xBCE4, "MOV:G.B", "@H'F862, R0", [0xF862]),
+                    instruction(0xBCE8, "MOV:G.B", "R0, @H'F851", [0xF851]),
+                    instruction(0xBCEC, "MOV:G.W", "@(-H'2000,R4), R0"),
+                    instruction(0xBCF0, "MOV:G.B", "R0, @H'F854", [0xF854]),
+                    instruction(0xBCF4, "SWAP.B", "R0"),
+                    instruction(0xBCF6, "MOV:G.B", "R0, @H'F853", [0xF853]),
+                    instruction(0xBCFA, "BSR", "loc_BA26", targets=[0xBA26]),
+                ]
+            ),
+        )
+
+        schema = semantics["response_schema"][0]
+        byte_sources = {item["offset"]: item["source_expression"] for item in schema["bytes"]}
+        self.assertEqual(byte_sources[0], "0x04")
+        self.assertEqual(byte_sources[1], "rx[2]")
+        self.assertEqual(byte_sources[2], "stale/unchanged")
+        self.assertEqual(byte_sources[3], "primary_value_table_candidate")
+        self.assertEqual(byte_sources[4], "primary_value_table_candidate")
+        self.assertIn("avoid a fixed 04 00 qq hi lo", semantic_text(schema))
+
+    def test_actual_be4d_retry_error_echo_copies_rx_payload(self):
+        semantics = only_semantics(
+            self,
+            base_payload(
+                [
+                    instruction(0xBE4B, "BRA", "loc_BE6D", targets=[0xBE6D]),
+                    instruction(0xBE4D, "MOV:G.B", "#H'07, @H'F850", [0xF850]),
+                    instruction(0xBE52, "MOV:G.B", "@H'F861, R0", [0xF861]),
+                    instruction(0xBE56, "MOV:G.B", "R0, @H'F851", [0xF851]),
+                    instruction(0xBE5A, "MOV:G.W", "@H'F862, R0", [0xF862]),
+                    instruction(0xBE5E, "MOV:G.W", "R0, @H'F852", [0xF852]),
+                    instruction(0xBE62, "MOV:G.B", "@H'F864, R0", [0xF864]),
+                    instruction(0xBE66, "MOV:G.B", "R0, @H'F854", [0xF854]),
+                    instruction(0xBE6A, "BSR", "loc_BA26", targets=[0xBA26]),
+                ]
+            ),
+        )
+
+        schema = semantics["response_schema"][0]
+        byte_sources = {item["offset"]: item["source_expression"] for item in schema["bytes"]}
+        self.assertEqual(byte_sources, {0: "0x07", 1: "rx[1]", 2: "rx[2]", 3: "rx[3]", 4: "rx[4]"})
+        self.assertIn("80 40 20 90", semantic_text(schema))
+        self.assertIn("not a table", semantic_text(schema))
+
     def test_timer_interrupt_model_surfaces_frt2_idle_heartbeat_counter(self):
         semantics = only_semantics(
             self,