SyncValsverifier → artifact → classifier → verdict
SyncVals · Trajectory

open-drain-command-engine

codex gpt-5.5 ✓ resolved GOOD_SUCCESS ↑ View task
Solved from the instruction alone, tests/ and solution/ were withheld from the agent's workspace and restored only for grading.
Reward = tests/test.sh exit code (0 → resolved); the classification below is post-hoc and cannot change it.
Classification , post-hoc; cannot change the reward
GOOD_SUCCESSLegitimate solve, implements the asked-for behavior; tests verify real functionality.
SubtypeLegitimate Solution
EvidenceTest output: 'MISMATCH_COUNTS cmd_ack=0 busy=0 al=0 bit_out=0 scl=0 sda=0' with 'mismatches=0 samples=2351'. Agent implemented TopModule with correct port list, instantiated I2CCommandController submodule, implemented 13-state synchronous FSM covering all four commands (START/STOP/WRITE/READ), proper open-drain line control with setup/wait/ack phases, SCL-stretch awareness with output registration across phase transitions, and sticky arbitration detection on START/WRITE-1 high-SCL edges. iVerilog syntax verification passed with no errors. Solution correctly interprets complex timing semantics: command-accept loads only first phase without consuming line samples, wait states hold drives while observing SCL, transitions occur after SCL-high is observed on next clock."
Root causeAgent successfully decoded a complex I2C protocol specification with multiple timing constraints and implemented a correct synchronous FSM-based solution that passes all 2351 test samples with zero output mismatches.
RecommendationN/A - task is fine
Trajectory
Tool-by-tool agent trajectory
6 tool calls · 2 tool types · 14 steps
<permissions instructions> Filesystem sandboxing defines which files can be read or written. `sandbox_mode` is `danger-full-access`: No filesystem sandboxing - all commands are permitted. Network access is enabled. Approval policy is currently never. Do not provide the `sandbox_permissions` for any reason, commands will be rejected. </permissions instructions><apps_instructions> ## Apps (Connectors) Apps (Connectors) can be explicitly triggered in user messages in the format `[$app-name](app://{connector_id})`. Apps can also be implicitly triggered as long as the context suggests usage of available apps. An app is equivalent to a set of MCP tools within the `codex_apps` MCP. An installed app's MCP tools are either provided to you already, or can be lazy-loaded through the `tool_search` tool. If `tool_search` is available, the apps that are searchable by `tools_search` will be listed by it. Do not additionally call list_mcp_resources or list_mcp_resource_templates for apps. </apps_instructions><skills_instructions> ## Skills A skill is a set of instructions provided through a `SKILL.md` source. Below is the list of skills that can be used. Each entry includes a name, description, and source locator. `file` locators are on the host filesystem, `environment resource` locators are owned by an execution environment, `orchestrator resource` locators are opaque non-filesystem resources, and `custom resource` locators use their provider's access mechanism. ### Available skills - imagegen: Generate or edit raster images when the task benefits from AI-created bitmap visuals such as photos, illustrations, textures, sprites, mockups, or transparent-background cutouts. Use when Codex should create a brand-new image, transform an existing image, or derive visual variants from references, and the output should be a bitmap asset rather than repo-native code or vector. 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(file: /tmp/codex-home/skills/.system/skill-installer/SKILL.md) ### How to use skills - Discovery: The list above is the skills available in this session (name + description + source locator). `file` entries live on the host filesystem, `environment resource` entries are owned by their execution environment, `orchestrator resource` entries must be accessed through `skills.list` and `skills.read`, and `custom resource` entries use their provider's access mechanism. - Trigger rules: If the user names a skill (with `$SkillName` or plain text) OR the task clearly matches a skill's description shown above, you must use that skill for that turn. Multiple mentions mean use them all. Do not carry skills across turns unless re-mentioned. - Missing/blocked: If a named skill isn't in the list or its source can't be read, say so briefly and continue with the best fallback. - How to use a skill (progressive disclosure): 1) After deciding to use a skill, the main agent must read its `SKILL.md` completely before taking task actions. For a `file` entry, open the listed path. For an `environment resource`, use the filesystem of the owning environment. For an `orchestrator resource`, call `skills.list` with `{"authority":{"kind":"orchestrator"}}`, select the matching package, and pass its `main_resource` to `skills.read`. If a read is truncated or paginated, continue until EOF. 2) When `SKILL.md` references another resource, use the same access mechanism. Resolve relative paths against a filesystem-backed skill directory. For orchestrator skills, pass the exact referenced resource identifier with the same authority and package to `skills.read`; do not treat `skill://` identifiers as filesystem paths. 3) If `SKILL.md` points to extra folders such as `references/`, use its routing instructions to identify the resources required for the task. The main agent must read each required instruction or reference file itself before acting on it. Do not delegate reading, summarizing, or interpreting skill instructions to a subagent. Subagents may still perform task work when the selected skill allows it. 4) For filesystem-backed skills, prefer running or patching provided scripts instead of retyping large code blocks. For orchestrator skills, use `skills.read` and the available tools; do not invent a local path. 5) Reuse provided assets or templates through the same source access mechanism instead of recreating them. - Coordination and sequencing: - If multiple skills apply, choose the minimal set that covers the request and state the order you'll use them. - Announce which skill(s) you're using and why (one short line). If you skip an obvious skill, say why. - Context hygiene: - Progressive disclosure applies to selecting relevant files, not partially reading a selected instruction file. Do not load unrelated references, scripts, or assets. - Avoid deep reference-chasing: prefer opening only files directly linked from `SKILL.md` unless you're blocked. - When variants exist (frameworks, providers, domains), pick only the relevant reference file(s) and note that choice. - Safety and fallback: If a skill can't be applied cleanly (missing files, unclear instructions), state the issue, pick the next-best approach, and continue. </skills_instructions>
<environment_context> <cwd>/app</cwd> <shell>bash</shell> <current_date>2026-06-20</current_date> <timezone>Etc/UTC</timezone> <filesystem><workspace_roots><root>/app</root></workspace_roots><permission_profile type="disabled"><file_system type="unrestricted" /></permission_profile></filesystem> </environment_context>
Implement `/app/dut.sv`. Define `TopModule` with this port list: `input clk, rst, cmd_valid, bit_in, scl_i, sda_i; input [1:0] cmd; output cmd_ack, busy, al, bit_out, scl_drive_low, sda_drive_low;`. Define another module and instantiate it from `TopModule`. `rst` is synchronous active high and clears outputs to 0. All outputs are registered. `cmd_ack` is a one-cycle completion pulse. Accept a command only when none is active; `cmd=0` may be accepted while idle or busy, and other commands only while `busy` is high. Illegal commands leave outputs unchanged and do not acknowledge. The line controls are open-drain: 1 pulls low, 0 releases. The command-accept edge only loads the first registered phase; it must not also consume `scl_i` or sample `sda_i` for phase completion. Because every output is registered, when a later phase says "until `scl_i` is high", the clock edge that observes high only records that fact; the next visible line-drive/ack phase appears on the following clock. Command acceptance itself is a visible registered phase: for stop, write, and read, the line-drive values loaded on the accept edge must be held through one additional full clocked setup cycle before the SCL-release phase begins. `cmd=0` starts or restarts ownership: release both lines on accept, then in following clocked wait phase keep both released until `scl_i` is high, keep SCL released while pulling SDA low for one full cycle, then pull SCL low and pulse `cmd_ack`; `busy` is set from the accept edge. `cmd=1` stops: drive both low on accept, keep both low for the following setup cycle, release SCL until `scl_i` is high, then release SDA, clear `busy`, and pulse `cmd_ack` on the following clock. `cmd=2` writes `bit_in`: on accept drive SCL low and drive SDA low for 0 or released for 1, keep those drive values for the following setup cycle, release SCL until `scl_i` is high, then pull SCL low and acknowledge on the following clock. `cmd=3` reads: on accept drive SCL low and release SDA, keep those drive values for the following setup cycle, release SCL until `scl_i` is high, sample `sda_i` on that high-SCL edge into `bit_out`, then pull SCL low and acknowledge on the following clock. `al` is sticky until reset and asserts only during start or write-1 high-SCL phases when released SDA is observed low.
I’ll inspect the workspace and current `dut.sv` before editing so the implementation fits whatever harness is present.
shell
pwd && rg --files -n /app | head -100
output
Chunk ID: 354a0b
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2
Output:
/app
shell
sed -n '1,240p' /app/dut.sv
output
Chunk ID: 64fbb3
Wall time: 0.0000 seconds
Process exited with code 2
Original token count: 14
Output:
sed: can't read /app/dut.sv: No such file or directory
shell
ls -la /app
output
Chunk ID: d6a34e
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 24
Output:
total 8
drwxr-xr-x 2 root root 4096 Jun 19 22:02 .
drwxr-xr-x 1 root root 4096 Jun 20 17:27 ..
The workspace is empty, so I’m creating `dut.sv` from scratch. I’m using a small controller module under `TopModule`; the FSM will keep output changes Moore-style so SCL-high detection affects the next visible cycle, as requested.
I’m going to add a single synchronous FSM. The only slightly subtle part is separating “observe `scl_i` high” from the following output phase, so wait states hold their current line drives on the observing edge and advance the visible action one clock later.
apply_patch
*** Begin Patch
*** Add File: /app/dut.sv
+module TopModule (
+    input clk, rst, cmd_valid, bit_in, scl_i, sda_i,
+    input [1:0] cmd,
+    output cmd_ack, busy, al, bit_out, scl_drive_low, sda_drive_low
+);
+
+    I2CCommandController controller (
+        .clk(clk),
+        .rst(rst),
+        .cmd_valid(cmd_valid),
+        .cmd(cmd),
+        .bit_in(bit_in),
+        .scl_i(scl_i),
+        .sda_i(sda_i),
+        .cmd_ack(cmd_ack),
+        .busy(busy),
+        .al(al),
+        .bit_out(bit_out),
+        .scl_drive_low(scl_drive_low),
+        .sda_drive_low(sda_drive_low)
+    );
+
+endmodule
+
+module I2CCommandController (
+    input  logic       clk,
+    input  logic       rst,
+    input  logic       cmd_valid,
+    input  logic [1:0] cmd,
+    input  logic       bit_in,
+    input  logic       scl_i,
+    input  logic       sda_i,
+    output logic       cmd_ack,
+    output logic       busy,
+    output logic       al,
+    output logic       bit_out,
+    output logic       scl_drive_low,
+    output logic       sda_drive_low
+);
+
+    localparam logic [1:0] CMD_START = 2'd0;
+    localparam logic [1:0] CMD_STOP  = 2'd1;
+    localparam logic [1:0] CMD_WRITE = 2'd2;
+    localparam logic [1:0] CMD_READ  = 2'd3;
+
+    typedef enum logic [3:0] {
+        ST_IDLE,
+        ST_START_WAIT_SCL,
+        ST_START_SDA_LOW,
+        ST_START_ACK,
+        ST_STOP_SETUP,
+        ST_STOP_WAIT_SCL,
+        ST_STOP_ACK,
+        ST_WRITE_SETUP,
+        ST_WRITE_WAIT_SCL,
+        ST_WRITE_ACK,
+        ST_READ_SETUP,
+        ST_READ_WAIT_SCL,
+        ST_READ_ACK
+    } state_t;
+
+    state_t state;
+    logic write_one;
+
+    always_ff @(posedge clk) begin
+        if (rst) begin
+            state         <= ST_IDLE;
+            write_one     <= 1'b0;
+            cmd_ack       <= 1'b0;
+            busy          <= 1'b0;
+            al            <= 1'b0;
+            bit_out       <= 1'b0;
+            scl_drive_low <= 1'b0;
+            sda_drive_low <= 1'b0;
+        end else begin
+            case (state)
+                ST_IDLE: begin
+                    if (cmd_valid && (cmd == CMD_START)) begin
+                        state         <= ST_START_WAIT_SCL;
+                        cmd_ack       <= 1'b0;
+                        busy          <= 1'b1;
+                        scl_drive_low <= 1'b0;
+                        sda_drive_low <= 1'b0;
+                    end else if (cmd_valid && busy && (cmd == CMD_STOP)) begin
+                        state         <= ST_STOP_SETUP;
+                        cmd_ack       <= 1'b0;
+                        scl_drive_low <= 1'b1;
+                        sda_drive_low <= 1'b1;
+                    end else if (cmd_valid && busy && (cmd == CMD_WRITE)) begin
+                        state         <= ST_WRITE_SETUP;
+                        write_one     <= bit_in;
+                        cmd_ack       <= 1'b0;
+                        scl_drive_low <= 1'b1;
+                        sda_drive_low <= ~bit_in;
+                    end else if (cmd_valid && busy && (cmd == CMD_READ)) begin
+                        state         <= ST_READ_SETUP;
+                        cmd_ack       <= 1'b0;
+                        scl_drive_low <= 1'b1;
+                        sda_drive_low <= 1'b0;
+                    end else begin
+                        cmd_ack <= 1'b0;
+                    end
+                end
+
+                ST_START_WAIT_SCL: begin
+                    cmd_ack       <= 1'b0;
+                    busy          <= 1'b1;
+                    scl_drive_low <= 1'b0;
+                    sda_drive_low <= 1'b0;
+                    if (scl_i) begin
+                        if (!sda_i) begin
+                            al <= 1'b1;
+                        end
+                        state <= ST_START_SDA_LOW;
+                    end
+                end
+
+                ST_START_SDA_LOW: begin
+                    state         <= ST_START_ACK;
+                    cmd_ack       <= 1'b0;
+                    busy          <= 1'b1;
+                    scl_drive_low <= 1'b0;
+                    sda_drive_low <= 1'b1;
+                end
+
+                ST_START_ACK: begin
+                    state         <= ST_IDLE;
+                    cmd_ack       <= 1'b1;
+                    busy          <= 1'b1;
+                    scl_drive_low <= 1'b1;
+                    sda_drive_low <= 1'b1;
+                end
+
+                ST_STOP_SETUP: begin
+                    state         <= ST_STOP_WAIT_SCL;
+                    cmd_ack       <= 1'b0;
+                    scl_drive_low <= 1'b1;
+                    sda_drive_low <= 1'b1;
+                end
+
+                ST_STOP_WAIT_SCL: begin
+                    cmd_ack       <= 1'b0;
+                    scl_drive_low <= 1'b0;
+                    sda_drive_low <= 1'b1;
+                    if (scl_i) begin
+                        state <= ST_STOP_ACK;
+                    end
+                end
+
+                ST_STOP_ACK: begin
+                    state         <= ST_IDLE;
+                    cmd_ack       <= 1'b1;
+                    busy          <= 1'b0;
+                    scl_drive_low <= 1'b0;
+                    sda_drive_low <= 1'b0;
+                end
+
+                ST_WRITE_SETUP: begin
+                    state         <= ST_WRITE_WAIT_SCL;
+                    cmd_ack       <= 1'b0;
+                    scl_drive_low <= 1'b1;
+                    sda_drive_low <= ~write_one;
+                end
+
+                ST_WRITE_WAIT_SCL: begin
+                    cmd_ack       <= 1'b0;
+                    scl_drive_low <= 1'b0;
+                    sda_drive_low <= ~write_one;
+                    if (scl_i) begin
+                        if (write_one && !sda_i) begin
+                            al <= 1'b1;
+                        end
+                        state <= ST_WRITE_ACK;
+                    end
+                end
+
+                ST_WRITE_ACK: begin
+                    state         <= ST_IDLE;
+                    cmd_ack       <= 1'b1;
+                    scl_drive_low <= 1'b1;
+                    sda_drive_low <= ~write_one;
+                end
+
+                ST_READ_SETUP: begin
+                    state         <= ST_READ_WAIT_SCL;
+                    cmd_ack       <= 1'b0;
+                    scl_drive_low <= 1'b1;
+                    sda_drive_low <= 1'b0;
+                end
+
+                ST_READ_WAIT_SCL: begin
+                    cmd_ack       <= 1'b0;
+                    scl_drive_low <= 1'b0;
+                    sda_drive_low <= 1'b0;
+                    if (scl_i) begin
+                        bit_out <= sda_i;
+                        state   <= ST_READ_ACK;
+                    end
+                end
+
+                ST_READ_ACK: begin
+                    state         <= ST_IDLE;
+                    cmd_ack       <= 1'b1;
+                    scl_drive_low <= 1'b1;
+                    sda_drive_low <= 1'b0;
+                end
+
+                default: begin
+                    state   <= ST_IDLE;
+                    cmd_ack <= 1'b0;
+                end
+            endcase
+        end
+    end
+
+endmodule
*** End Patch


Exit code: 0
Wall time: 0 seconds
Output:
Success. Updated the following files:
A /app/dut.sv
The file is in place. I’m checking syntax now, and then I’ll do a quick pass against the timing bullets to catch off-by-one phase mistakes.
shell
iverilog -g2012 -Wall -tnull /app/dut.sv
output
Chunk ID: d2ef1a
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 0
Output:
shell
nl -ba /app/dut.sv | sed -n '1,260p'
output
Chunk ID: 4cd9ee
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2136
Output:
     1	module TopModule (
     2	    input clk, rst, cmd_valid, bit_in, scl_i, sda_i,
     3	    input [1:0] cmd,
     4	    output cmd_ack, busy, al, bit_out, scl_drive_low, sda_drive_low
     5	);
     6	
     7	    I2CCommandController controller (
     8	        .clk(clk),
     9	        .rst(rst),
    10	        .cmd_valid(cmd_valid),
    11	        .cmd(cmd),
    12	        .bit_in(bit_in),
    13	        .scl_i(scl_i),
    14	        .sda_i(sda_i),
    15	        .cmd_ack(cmd_ack),
    16	        .busy(busy),
    17	        .al(al),
    18	        .bit_out(bit_out),
    19	        .scl_drive_low(scl_drive_low),
    20	        .sda_drive_low(sda_drive_low)
    21	    );
    22	
    23	endmodule
    24	
    25	module I2CCommandController (
    26	    input  logic       clk,
    27	    input  logic       rst,
    28	    input  logic       cmd_valid,
    29	    input  logic [1:0] cmd,
    30	    input  logic       bit_in,
    31	    input  logic       scl_i,
    32	    input  logic       sda_i,
    33	    output logic       cmd_ack,
    34	    output logic       busy,
    35	    output logic       al,
    36	    output logic       bit_out,
    37	    output logic       scl_drive_low,
    38	    output logic       sda_drive_low
    39	);
    40	
    41	    localparam logic [1:0] CMD_START = 2'd0;
    42	    localparam logic [1:0] CMD_STOP  = 2'd1;
    43	    localparam logic [1:0] CMD_WRITE = 2'd2;
    44	    localparam logic [1:0] CMD_READ  = 2'd3;
    45	
    46	    typedef enum logic [3:0] {
    47	        ST_IDLE,
    48	        ST_START_WAIT_SCL,
    49	        ST_START_SDA_LOW,
    50	        ST_START_ACK,
    51	        ST_STOP_SETUP,
    52	        ST_STOP_WAIT_SCL,
    53	        ST_STOP_ACK,
    54	        ST_WRITE_SETUP,
    55	        ST_WRITE_WAIT_SCL,
    56	        ST_WRITE_ACK,
    57	        ST_READ_SETUP,
    58	        ST_READ_WAIT_SCL,
    59	        ST_READ_ACK
    60	    } state_t;
    61	
    62	    state_t state;
    63	    logic write_one;
    64	
    65	    always_ff @(posedge clk) begin
    66	        if (rst) begin
    67	            state         <= ST_IDLE;
    68	            write_one     <= 1'b0;
    69	            cmd_ack       <= 1'b0;
    70	            busy          <= 1'b0;
    71	            al            <= 1'b0;
    72	            bit_out       <= 1'b0;
    73	            scl_drive_low <= 1'b0;
    74	            sda_drive_low <= 1'b0;
    75	        end else begin
    76	            case (state)
    77	                ST_IDLE: begin
    78	                    if (cmd_valid && (cmd == CMD_START)) begin
    79	                        state         <= ST_START_WAIT_SCL;
    80	                        cmd_ack       <= 1'b0;
    81	                        busy          <= 1'b1;
    82	                        scl_drive_low <= 1'b0;
    83	                        sda_drive_low <= 1'b0;
    84	                    end else if (cmd_valid && busy && (cmd == CMD_STOP)) begin
    85	                        state         <= ST_STOP_SETUP;
    86	                        cmd_ack       <= 1'b0;
    87	                        scl_drive_low <= 1'b1;
    88	                        sda_drive_low <= 1'b1;
    89	                    end else if (cmd_valid && busy && (cmd == CMD_WRITE)) begin
    90	                        state         <= ST_WRITE_SETUP;
    91	                        write_one     <= bit_in;
    92	                        cmd_ack       <= 1'b0;
    93	                        scl_drive_low <= 1'b1;
    94	                        sda_drive_low <= ~bit_in;
    95	                    end else if (cmd_valid && busy && (cmd == CMD_READ)) begin
    96	                        state         <= ST_READ_SETUP;
    97	                        cmd_ack       <= 1'b0;
    98	                        scl_drive_low <= 1'b1;
    99	                        sda_drive_low <= 1'b0;
   100	                    end else begin
   101	                        cmd_ack <= 1'b0;
   102	                    end
   103	                end
   104	
   105	                ST_START_WAIT_SCL: begin
   106	                    cmd_ack       <= 1'b0;
   107	                    busy          <= 1'b1;
   108	                    scl_drive_low <= 1'b0;
   109	                    sda_drive_low <= 1'b0;
   110	                    if (scl_i) begin
   111	                        if (!sda_i) begin
   112	                            al <= 1'b1;
   113	                        end
   114	                        state <= ST_START_SDA_LOW;
   115	                    end
   116	                end
   117	
   118	                ST_START_SDA_LOW: begin
   119	                    state         <= ST_START_ACK;
   120	                    cmd_ack       <= 1'b0;
   121	                    busy          <= 1'b1;
   122	                    scl_drive_low <= 1'b0;
   123	                    sda_drive_low <= 1'b1;
   124	                end
   125	
   126	                ST_START_ACK: begin
   127	                    state         <= ST_IDLE;
   128	                    cmd_ack       <= 1'b1;
   129	                    busy          <= 1'b1;
   130	                    scl_drive_low <= 1'b1;
   131	                    sda_drive_low <= 1'b1;
   132	                end
   133	
   134	                ST_STOP_SETUP: begin
   135	                    state         <= ST_STOP_WAIT_SCL;
   136	                    cmd_ack       <= 1'b0;
   137	                    scl_drive_low <= 1'b1;
   138	                    sda_drive_low <= 1'b1;
   139	                end
   140	
   141	                ST_STOP_WAIT_SCL: begin
   142	                    cmd_ack       <= 1'b0;
   143	                    scl_drive_low <= 1'b0;
   144	                    sda_drive_low <= 1'b1;
   145	                    if (scl_i) begin
   146	                        state <= ST_STOP_ACK;
   147	                    end
   148	                end
   149	
   150	                ST_STOP_ACK: begin
   151	                    state         <= ST_IDLE;
   152	                    cmd_ack       <= 1'b1;
   153	                    busy          <= 1'b0;
   154	                    scl_drive_low <= 1'b0;
   155	                    sda_drive_low <= 1'b0;
   156	                end
   157	
   158	                ST_WRITE_SETUP: begin
   159	                    state         <= ST_WRITE_WAIT_SCL;
   160	                    cmd_ack       <= 1'b0;
   161	                    scl_drive_low <= 1'b1;
   162	                    sda_drive_low <= ~write_one;
   163	                end
   164	
   165	                ST_WRITE_WAIT_SCL: begin
   166	                    cmd_ack       <= 1'b0;
   167	                    scl_drive_low <= 1'b0;
   168	                    sda_drive_low <= ~write_one;
   169	                    if (scl_i) begin
   170	                        if (write_one && !sda_i) begin
   171	                            al <= 1'b1;
   172	                        end
   173	                        state <= ST_WRITE_ACK;
   174	                    end
   175	                end
   176	
   177	                ST_WRITE_ACK: begin
   178	                    state         <= ST_IDLE;
   179	                    cmd_ack       <= 1'b1;
   180	                    scl_drive_low <= 1'b1;
   181	                    sda_drive_low <= ~write_one;
   182	                end
   183	
   184	                ST_READ_SETUP: begin
   185	                    state         <= ST_READ_WAIT_SCL;
   186	                    cmd_ack       <= 1'b0;
   187	                    scl_drive_low <= 1'b1;
   188	                    sda_drive_low <= 1'b0;
   189	                end
   190	
   191	                ST_READ_WAIT_SCL: begin
   192	                    cmd_ack       <= 1'b0;
   193	                    scl_drive_low <= 1'b0;
   194	                    sda_drive_low <= 1'b0;
   195	                    if (scl_i) begin
   196	                        bit_out <= sda_i;
   197	                        state   <= ST_READ_ACK;
   198	                    end
   199	                end
   200	
   201	                ST_READ_ACK: begin
   202	                    state         <= ST_IDLE;
   203	                    cmd_ack       <= 1'b1;
   204	                    scl_drive_low <= 1'b1;
   205	                    sda_drive_low <= 1'b0;
   206	                end
   207	
   208	                default: begin
   209	                    state   <= ST_IDLE;
   210	                    cmd_ack <= 1'b0;
   211	                end
   212	            endcase
   213	        end
   214	    end
   215	
   216	endmodule
Implemented [dut.sv](/app/dut.sv) with `TopModule` instantiating `I2CCommandController`. The controller uses a synchronous registered FSM with: - synchronous active-high reset clearing all outputs - one-cycle `cmd_ack` completion pulses - legal command gating based on idle/internal active state and `busy` - open-drain line drive outputs - delayed SCL-high completion phases as specified - sticky `al` only for start/write-1 high-SCL arbitration checks Verified syntax with: ```bash iverilog -g2012 -Wall -tnull /app/dut.sv ```
Final diff , what the agent changed

No file changes, the agent left the workspace untouched.

Verifier output , the proof behind the reward
tests/test.sh
MISMATCH_COUNTS cmd_ack=0 busy=0 al=0 bit_out=0 scl=0 sda=0
__CHIPBENCH_MISMATCH_SUMMARY__: mismatches=0 samples=2351

Reproduce this trial: git checkout 2f94510 && PYTHONPATH=src python3 scripts/build_site.py , then open trial/trial_42f98e78328c4f0b. Re-running the agent live requires EVAL_PLATFORM_ENABLE_OAUTH_SMOKE=1 and is non-deterministic.

Trial trial_42f98e78328c4f0b · verifier authoritative; classifier explanatory.