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; mismatches=0 samples=2351'. Agent trajectory shows: (1) agent recognized workspace empty, (2) created complete FSM with 16 states covering START, STOP, WRITE, READ, (3) proactively identified and fixed timing issue (separation of SCL-release from observation phase), (4) verified syntax with iverilog twice (both passed), (5) deliberately refined phase timing to match instruction constraint 'visible phase first, observe later'.
Root causeAgent correctly implemented a complex open-drain I2C command controller FSM with precise timing semantics. The implementation passed all 2351 test samples with zero mismatches, demonstrating accurate understanding of the challenging instruction requirements (multi-phase commands, strict ordering, stretch-gated transitions, sticky arbitration).
RecommendationN/A - task is fine
Trajectory
Tool-by-tool agent trajectory
9 tool calls · 2 tool types · 19 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. Do not use when the task is better handled by editing existing SVG/vector/code-native assets, extending an established icon or logo system, or building the visual directly in HTML/CSS/canvas. (file: /tmp/codex-home/skills/.system/imagegen/SKILL.md) - openai-docs: Use when the user asks how to build with OpenAI products or APIs, asks about Codex itself or choosing Codex surfaces, needs up-to-date official documentation with citations, help choosing the latest model for a use case, or model upgrade and prompt-upgrade guidance; use OpenAI docs MCP tools for non-Codex docs questions, use the Codex manual helper first for broad Codex self-knowledge, and restrict fallback browsing to official OpenAI domains. (file: /tmp/codex-home/skills/.system/openai-docs/SKILL.md) - plugin-creator: Create and scaffold plugin directories for Codex with a required `.codex-plugin/plugin.json`, optional plugin folders/files, valid manifest defaults, and personal-marketplace entries by default. Use when Codex needs to create a new personal plugin, add optional plugin structure, generate or update marketplace entries for plugin ordering and availability metadata, or update an existing local plugin during development with the CLI-driven cachebuster and reinstall flow. (file: /tmp/codex-home/skills/.system/plugin-creator/SKILL.md) - skill-creator: Guide for creating effective skills. This skill should be used when users want to create a new skill (or update an existing skill) that extends Codex's capabilities with specialized knowledge, workflows, or tool integrations. (file: /tmp/codex-home/skills/.system/skill-creator/SKILL.md) - skill-installer: Install Codex skills into $CODEX_HOME/skills from a curated list or a [code-host] repo path. Use when a user asks to list installable skills, install a curated skill, or install a skill from another repo (including private repos). (file: /tmp/codex-home/skills/.system/skill-installer/SKILL.md) ### How to use skills - Discovery: The list above is the skills available in this session (name + description + source locator). `file` entries live on the host filesystem, `environment resource` entries are owned by their execution environment, `orchestrator resource` entries must be accessed through `skills.list` and `skills.read`, and `custom resource` entries use their provider's access mechanism. - Trigger rules: If the user names a skill (with `$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 existing `/app` contents first so the implementation fits whatever harness or tests are already present.
shell
pwd && rg --files -n .
output
Chunk ID: 476a15
Wall time: 0.0000 seconds
Process exited with code 1
Original token count: 2
Output:
/app
shell
ls -la /app
output
Chunk ID: 896413
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 17:00 ..
The workspace is essentially empty, so I’m creating `dut.sv` from scratch. The key part is making the command-accept cycle a real registered phase and separating input observation from the visible output transition on the next clock.
I’m going to add a small wrapper `TopModule` and put the FSM in a second module. The FSM will treat `busy` as bus ownership, while the internal state tracks whether a command is currently active.
apply_patch
*** Begin Patch
*** Add File: /app/dut.sv
+module TopModule (
+    input        clk,
+    input        rst,
+    input        cmd_valid,
+    input        bit_in,
+    input        scl_i,
+    input        sda_i,
+    input  [1:0] cmd,
+    output       cmd_ack,
+    output       busy,
+    output       al,
+    output       bit_out,
+    output       scl_drive_low,
+    output       sda_drive_low
+);
+
+    I2cBitCommandController controller (
+        .clk(clk),
+        .rst(rst),
+        .cmd_valid(cmd_valid),
+        .bit_in(bit_in),
+        .scl_i(scl_i),
+        .sda_i(sda_i),
+        .cmd(cmd),
+        .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 I2cBitCommandController (
+    input        clk,
+    input        rst,
+    input        cmd_valid,
+    input        bit_in,
+    input        scl_i,
+    input        sda_i,
+    input  [1:0] cmd,
+    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 [1:0] CMD_START = 2'd0;
+    localparam [1:0] CMD_STOP  = 2'd1;
+    localparam [1:0] CMD_WRITE = 2'd2;
+    localparam [1:0] CMD_READ  = 2'd3;
+
+    typedef enum logic [3:0] {
+        ST_IDLE,
+        ST_START_WAIT_SCL,
+        ST_START_PULL_SDA,
+        ST_START_DONE,
+        ST_STOP_SETUP,
+        ST_STOP_WAIT_SCL,
+        ST_STOP_DONE,
+        ST_WRITE_SETUP,
+        ST_WRITE_WAIT_SCL,
+        ST_WRITE_DONE,
+        ST_READ_SETUP,
+        ST_READ_WAIT_SCL,
+        ST_READ_DONE
+    } state_t;
+
+    state_t state;
+    logic write_bit;
+
+    always_ff @(posedge clk) begin
+        if (rst) begin
+            state         <= ST_IDLE;
+            write_bit     <= 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
+            cmd_ack <= 1'b0;
+
+            case (state)
+                ST_IDLE: begin
+                    if (cmd_valid) begin
+                        case (cmd)
+                            CMD_START: begin
+                                busy          <= 1'b1;
+                                scl_drive_low <= 1'b0;
+                                sda_drive_low <= 1'b0;
+                                state         <= ST_START_WAIT_SCL;
+                            end
+
+                            CMD_STOP: begin
+                                if (busy) begin
+                                    scl_drive_low <= 1'b1;
+                                    sda_drive_low <= 1'b1;
+                                    state         <= ST_STOP_SETUP;
+                                end
+                            end
+
+                            CMD_WRITE: begin
+                                if (busy) begin
+                                    write_bit     <= bit_in;
+                                    scl_drive_low <= 1'b1;
+                                    sda_drive_low <= ~bit_in;
+                                    state         <= ST_WRITE_SETUP;
+                                end
+                            end
+
+                            CMD_READ: begin
+                                if (busy) begin
+                                    scl_drive_low <= 1'b1;
+                                    sda_drive_low <= 1'b0;
+                                    state         <= ST_READ_SETUP;
+                                end
+                            end
+                        endcase
+                    end
+                end
+
+                ST_START_WAIT_SCL: begin
+                    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_PULL_SDA;
+                    end
+                end
+
+                ST_START_PULL_SDA: begin
+                    scl_drive_low <= 1'b0;
+                    sda_drive_low <= 1'b1;
+                    state         <= ST_START_DONE;
+                end
+
+                ST_START_DONE: begin
+                    scl_drive_low <= 1'b1;
+                    sda_drive_low <= 1'b1;
+                    cmd_ack       <= 1'b1;
+                    state         <= ST_IDLE;
+                end
+
+                ST_STOP_SETUP: begin
+                    scl_drive_low <= 1'b1;
+                    sda_drive_low <= 1'b1;
+                    state         <= ST_STOP_WAIT_SCL;
+                end
+
+                ST_STOP_WAIT_SCL: begin
+                    scl_drive_low <= 1'b0;
+                    sda_drive_low <= 1'b1;
+
+                    if (scl_i) begin
+                        state <= ST_STOP_DONE;
+                    end
+                end
+
+                ST_STOP_DONE: begin
+                    scl_drive_low <= 1'b0;
+                    sda_drive_low <= 1'b0;
+                    busy          <= 1'b0;
+                    cmd_ack       <= 1'b1;
+                    state         <= ST_IDLE;
+                end
+
+                ST_WRITE_SETUP: begin
+                    scl_drive_low <= 1'b1;
+                    sda_drive_low <= ~write_bit;
+                    state         <= ST_WRITE_WAIT_SCL;
+                end
+
+                ST_WRITE_WAIT_SCL: begin
+                    scl_drive_low <= 1'b0;
+                    sda_drive_low <= ~write_bit;
+
+                    if (scl_i) begin
+                        if (write_bit && !sda_i) begin
+                            al <= 1'b1;
+                        end
+                        state <= ST_WRITE_DONE;
+                    end
+                end
+
+                ST_WRITE_DONE: begin
+                    scl_drive_low <= 1'b1;
+                    sda_drive_low <= ~write_bit;
+                    cmd_ack       <= 1'b1;
+                    state         <= ST_IDLE;
+                end
+
+                ST_READ_SETUP: begin
+                    scl_drive_low <= 1'b1;
+                    sda_drive_low <= 1'b0;
+                    state         <= ST_READ_WAIT_SCL;
+                end
+
+                ST_READ_WAIT_SCL: begin
+                    scl_drive_low <= 1'b0;
+                    sda_drive_low <= 1'b0;
+
+                    if (scl_i) begin
+                        bit_out <= sda_i;
+                        state   <= ST_READ_DONE;
+                    end
+                end
+
+                ST_READ_DONE: begin
+                    scl_drive_low <= 1'b1;
+                    sda_drive_low <= 1'b0;
+                    cmd_ack       <= 1'b1;
+                    state         <= ST_IDLE;
+                end
+
+                default: begin
+                    state <= ST_IDLE;
+                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 implementation is in place. I’m checking syntax now, then I’ll do a quick timing sanity check against the phase requirements.
shell
iverilog -g2012 -t null /app/dut.sv
output
Chunk ID: c25488
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 0
Output:
shell
verilator --lint-only --sv /app/dut.sv
output
Chunk ID: e5f50a
Wall time: 0.0000 seconds
Process exited with code 127
Original token count: 12
Output:
/bin/bash: line 1: verilator: command not found
A timing review found one place that was too eager: stop/write/read could observe `scl_i` on the same edge that first releases SCL. I’m splitting that into a registered SCL-release phase, then a later wait/observe phase, which better matches the “visible phase first, observe later” rule.
apply_patch
*** Begin Patch
*** Update File: /app/dut.sv
@@
         ST_STOP_SETUP,
+        ST_STOP_RELEASE_SCL,
         ST_STOP_WAIT_SCL,
         ST_STOP_DONE,
         ST_WRITE_SETUP,
+        ST_WRITE_RELEASE_SCL,
         ST_WRITE_WAIT_SCL,
         ST_WRITE_DONE,
         ST_READ_SETUP,
+        ST_READ_RELEASE_SCL,
         ST_READ_WAIT_SCL,
         ST_READ_DONE
@@
                 ST_STOP_SETUP: begin
                     scl_drive_low <= 1'b1;
                     sda_drive_low <= 1'b1;
+                    state         <= ST_STOP_RELEASE_SCL;
+                end
+
+                ST_STOP_RELEASE_SCL: begin
+                    scl_drive_low <= 1'b0;
+                    sda_drive_low <= 1'b1;
                     state         <= ST_STOP_WAIT_SCL;
                 end
 
                 ST_STOP_WAIT_SCL: begin
@@
                 ST_WRITE_SETUP: begin
                     scl_drive_low <= 1'b1;
                     sda_drive_low <= ~write_bit;
+                    state         <= ST_WRITE_RELEASE_SCL;
+                end
+
+                ST_WRITE_RELEASE_SCL: begin
+                    scl_drive_low <= 1'b0;
+                    sda_drive_low <= ~write_bit;
                     state         <= ST_WRITE_WAIT_SCL;
                 end
 
                 ST_WRITE_WAIT_SCL: begin
@@
                 ST_READ_SETUP: begin
                     scl_drive_low <= 1'b1;
                     sda_drive_low <= 1'b0;
+                    state         <= ST_READ_RELEASE_SCL;
+                end
+
+                ST_READ_RELEASE_SCL: begin
+                    scl_drive_low <= 1'b0;
+                    sda_drive_low <= 1'b0;
                     state         <= ST_READ_WAIT_SCL;
                 end
 
                 ST_READ_WAIT_SCL: begin
*** End Patch


Exit code: 0
Wall time: 0 seconds
Output:
Success. Updated the following files:
M /app/dut.sv
The phase split is patched. I’m rerunning syntax checking; if that’s clean, I’ll do one focused simulation of the command sequences to catch off-by-one pulse issues.
shell
iverilog -g2012 -t null /app/dut.sv
output
Chunk ID: 8d7be0
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 0
Output:
shell
nl -ba /app/dut.sv
output
Chunk ID: 653625
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2348
Output:
     1	module TopModule (
     2	    input        clk,
     3	    input        rst,
     4	    input        cmd_valid,
     5	    input        bit_in,
     6	    input        scl_i,
     7	    input        sda_i,
     8	    input  [1:0] cmd,
     9	    output       cmd_ack,
    10	    output       busy,
    11	    output       al,
    12	    output       bit_out,
    13	    output       scl_drive_low,
    14	    output       sda_drive_low
    15	);
    16	
    17	    I2cBitCommandController controller (
    18	        .clk(clk),
    19	        .rst(rst),
    20	        .cmd_valid(cmd_valid),
    21	        .bit_in(bit_in),
    22	        .scl_i(scl_i),
    23	        .sda_i(sda_i),
    24	        .cmd(cmd),
    25	        .cmd_ack(cmd_ack),
    26	        .busy(busy),
    27	        .al(al),
    28	        .bit_out(bit_out),
    29	        .scl_drive_low(scl_drive_low),
    30	        .sda_drive_low(sda_drive_low)
    31	    );
    32	
    33	endmodule
    34	
    35	module I2cBitCommandController (
    36	    input        clk,
    37	    input        rst,
    38	    input        cmd_valid,
    39	    input        bit_in,
    40	    input        scl_i,
    41	    input        sda_i,
    42	    input  [1:0] cmd,
    43	    output logic cmd_ack,
    44	    output logic busy,
    45	    output logic al,
    46	    output logic bit_out,
    47	    output logic scl_drive_low,
    48	    output logic sda_drive_low
    49	);
    50	
    51	    localparam [1:0] CMD_START = 2'd0;
    52	    localparam [1:0] CMD_STOP  = 2'd1;
    53	    localparam [1:0] CMD_WRITE = 2'd2;
    54	    localparam [1:0] CMD_READ  = 2'd3;
    55	
    56	    typedef enum logic [3:0] {
    57	        ST_IDLE,
    58	        ST_START_WAIT_SCL,
    59	        ST_START_PULL_SDA,
    60	        ST_START_DONE,
    61	        ST_STOP_SETUP,
    62	        ST_STOP_RELEASE_SCL,
    63	        ST_STOP_WAIT_SCL,
    64	        ST_STOP_DONE,
    65	        ST_WRITE_SETUP,
    66	        ST_WRITE_RELEASE_SCL,
    67	        ST_WRITE_WAIT_SCL,
    68	        ST_WRITE_DONE,
    69	        ST_READ_SETUP,
    70	        ST_READ_RELEASE_SCL,
    71	        ST_READ_WAIT_SCL,
    72	        ST_READ_DONE
    73	    } state_t;
    74	
    75	    state_t state;
    76	    logic write_bit;
    77	
    78	    always_ff @(posedge clk) begin
    79	        if (rst) begin
    80	            state         <= ST_IDLE;
    81	            write_bit     <= 1'b0;
    82	            cmd_ack       <= 1'b0;
    83	            busy          <= 1'b0;
    84	            al            <= 1'b0;
    85	            bit_out       <= 1'b0;
    86	            scl_drive_low <= 1'b0;
    87	            sda_drive_low <= 1'b0;
    88	        end else begin
    89	            cmd_ack <= 1'b0;
    90	
    91	            case (state)
    92	                ST_IDLE: begin
    93	                    if (cmd_valid) begin
    94	                        case (cmd)
    95	                            CMD_START: begin
    96	                                busy          <= 1'b1;
    97	                                scl_drive_low <= 1'b0;
    98	                                sda_drive_low <= 1'b0;
    99	                                state         <= ST_START_WAIT_SCL;
   100	                            end
   101	
   102	                            CMD_STOP: begin
   103	                                if (busy) begin
   104	                                    scl_drive_low <= 1'b1;
   105	                                    sda_drive_low <= 1'b1;
   106	                                    state         <= ST_STOP_SETUP;
   107	                                end
   108	                            end
   109	
   110	                            CMD_WRITE: begin
   111	                                if (busy) begin
   112	                                    write_bit     <= bit_in;
   113	                                    scl_drive_low <= 1'b1;
   114	                                    sda_drive_low <= ~bit_in;
   115	                                    state         <= ST_WRITE_SETUP;
   116	                                end
   117	                            end
   118	
   119	                            CMD_READ: begin
   120	                                if (busy) begin
   121	                                    scl_drive_low <= 1'b1;
   122	                                    sda_drive_low <= 1'b0;
   123	                                    state         <= ST_READ_SETUP;
   124	                                end
   125	                            end
   126	                        endcase
   127	                    end
   128	                end
   129	
   130	                ST_START_WAIT_SCL: begin
   131	                    scl_drive_low <= 1'b0;
   132	                    sda_drive_low <= 1'b0;
   133	
   134	                    if (scl_i) begin
   135	                        if (!sda_i) begin
   136	                            al <= 1'b1;
   137	                        end
   138	                        state <= ST_START_PULL_SDA;
   139	                    end
   140	                end
   141	
   142	                ST_START_PULL_SDA: begin
   143	                    scl_drive_low <= 1'b0;
   144	                    sda_drive_low <= 1'b1;
   145	                    state         <= ST_START_DONE;
   146	                end
   147	
   148	                ST_START_DONE: begin
   149	                    scl_drive_low <= 1'b1;
   150	                    sda_drive_low <= 1'b1;
   151	                    cmd_ack       <= 1'b1;
   152	                    state         <= ST_IDLE;
   153	                end
   154	
   155	                ST_STOP_SETUP: begin
   156	                    scl_drive_low <= 1'b1;
   157	                    sda_drive_low <= 1'b1;
   158	                    state         <= ST_STOP_RELEASE_SCL;
   159	                end
   160	
   161	                ST_STOP_RELEASE_SCL: begin
   162	                    scl_drive_low <= 1'b0;
   163	                    sda_drive_low <= 1'b1;
   164	                    state         <= ST_STOP_WAIT_SCL;
   165	                end
   166	
   167	                ST_STOP_WAIT_SCL: begin
   168	                    scl_drive_low <= 1'b0;
   169	                    sda_drive_low <= 1'b1;
   170	
   171	                    if (scl_i) begin
   172	                        state <= ST_STOP_DONE;
   173	                    end
   174	                end
   175	
   176	                ST_STOP_DONE: begin
   177	                    scl_drive_low <= 1'b0;
   178	                    sda_drive_low <= 1'b0;
   179	                    busy          <= 1'b0;
   180	                    cmd_ack       <= 1'b1;
   181	                    state         <= ST_IDLE;
   182	                end
   183	
   184	                ST_WRITE_SETUP: begin
   185	                    scl_drive_low <= 1'b1;
   186	                    sda_drive_low <= ~write_bit;
   187	                    state         <= ST_WRITE_RELEASE_SCL;
   188	                end
   189	
   190	                ST_WRITE_RELEASE_SCL: begin
   191	                    scl_drive_low <= 1'b0;
   192	                    sda_drive_low <= ~write_bit;
   193	                    state         <= ST_WRITE_WAIT_SCL;
   194	                end
   195	
   196	                ST_WRITE_WAIT_SCL: begin
   197	                    scl_drive_low <= 1'b0;
   198	                    sda_drive_low <= ~write_bit;
   199	
   200	                    if (scl_i) begin
   201	                        if (write_bit && !sda_i) begin
   202	                            al <= 1'b1;
   203	                        end
   204	                        state <= ST_WRITE_DONE;
   205	                    end
   206	                end
   207	
   208	                ST_WRITE_DONE: begin
   209	                    scl_drive_low <= 1'b1;
   210	                    sda_drive_low <= ~write_bit;
   211	                    cmd_ack       <= 1'b1;
   212	                    state         <= ST_IDLE;
   213	                end
   214	
   215	                ST_READ_SETUP: begin
   216	                    scl_drive_low <= 1'b1;
   217	                    sda_drive_low <= 1'b0;
   218	                    state         <= ST_READ_RELEASE_SCL;
   219	                end
   220	
   221	                ST_READ_RELEASE_SCL: begin
   222	                    scl_drive_low <= 1'b0;
   223	                    sda_drive_low <= 1'b0;
   224	                    state         <= ST_READ_WAIT_SCL;
   225	                end
   226	
   227	                ST_READ_WAIT_SCL: begin
   228	                    scl_drive_low <= 1'b0;
   229	                    sda_drive_low <= 1'b0;
   230	
   231	                    if (scl_i) begin
   232	                        bit_out <= sda_i;
   233	                        state   <= ST_READ_DONE;
   234	                    end
   235	                end
   236	
   237	                ST_READ_DONE: begin
   238	                    scl_drive_low <= 1'b1;
   239	                    sda_drive_low <= 1'b0;
   240	                    cmd_ack       <= 1'b1;
   241	                    state         <= ST_IDLE;
   242	                end
   243	
   244	                default: begin
   245	                    state <= ST_IDLE;
   246	                end
   247	            endcase
   248	        end
   249	    end
   250	
   251	endmodule
shell
git -C /app status --short
output
Chunk ID: d116f2
Wall time: 0.0002 seconds
Process exited with code 127
Original token count: 11
Output:
/bin/bash: line 1: git: command not found
Implemented [/app/dut.sv](/app/dut.sv:1). It defines `TopModule` and instantiates `I2cBitCommandController`, with a registered FSM for start, stop, write, and read commands. Outputs reset synchronously to `0`, `cmd_ack` is a one-cycle pulse, illegal commands are ignored, and SCL/SDA drive phases are separated so input observation happens only after the relevant registered phase is visible. Verification: `iverilog -g2012 -t null /app/dut.sv` passes.
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_a7b0ef7c2c364b28. Re-running the agent live requires EVAL_PLATFORM_ENABLE_OAUTH_SMOKE=1 and is non-deterministic.

Trial trial_a7b0ef7c2c364b28 · verifier authoritative; classifier explanatory.