SyncValsverifier → artifact → classifier → verdict
SyncVals · Trajectory

coprocessor-dispatcher-classmix

claude-code claude-opus-4-8 ✗ failed GOOD_FAILURE ↑ 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_FAILUREHonest miss, the agent ran correctly but couldn't solve it. Expected for a hard task; the task is sound.
SubtypeImplementation Bugs
EvidenceVerifier output: `TEST reference_equivalence: FAIL (363 mismatches in 1093 samples)`. The instruction states `rst is synchronous active high and clears all slots, registered outputs, and inflight_o` and `A writeback pulses wb_valid_o for one cycle ... on that edge`; the reference solution updates `wb_valid_o <= wb_fire; wb_rd_o <= wb_rd_sel; wb_data_o <= wb_data_sel;` inside `always @(posedge clk)`. The agent instead implemented `always @* begin wb_valid_o = 1'b0; ... if (sel0) wb_valid_o = 1'b1; ... end`, making writeback outputs combinational.
Root causeThe task is well-specified and the tests compare behavioral equivalence against the stated timing contract. The agent misunderstood/implemented the writeback timing incorrectly, especially by driving registered writeback outputs combinationally, causing many reference mismatches.
RecommendationN/A - task is fine
Trajectory
Tool-by-tool agent trajectory
1 tool calls · 1 tool types · 3 steps
Write /app/dut.sv defining TopModule with ports clk, rst, op_valid_i, op_class_i[1:0], op_rd_i[1:0], op_data_i[15:0], c2_done_i, op_accept_o, wb_valid_o, wb_rd_o[1:0], wb_data_o[15:0], c2_busy_o, and inflight_o[3:0]. rst is synchronous active high and clears all slots, registered outputs, and inflight_o. op_accept_o and c2_busy_o are combinational. There is one slot for each class 0, 1, and 2. Accept a request combinationally exactly when op_valid_i=1, its destination bit is not set in registered inflight_o, and its class slot is empty; rejected requests are dropped. Requests with op_class_i=3 are never accepted or stored. On the accepting edge, store the request and set that destination bit. Class 0 writes back op_data_i+1 one cycle after accept. Class 1 writes back op_data_i*2 two cycles after accept. Class 2 stores op_data_i ^ 16'hffff; it becomes ready once c2_done_i is high at an edge while busy. Readiness is sticky until the writeback fires, even if c2_done_i drops. c2_busy_o is high exactly while that slot is occupied, including before an edge that writes it back. Only one writeback may occur per cycle. Ready priority is class 0, then 1, then 2; blocked slots stay ready and are not dropped. A writeback pulses wb_valid_o for one cycle and carries the selected destination/data; on that edge the slot frees and inflight_o clears that destination. wb_rd_o and wb_data_o are checked only when wb_valid_o=1. Do not use simulator/file-I/O tasks, preprocessor directives, DPI, force/release, or hidden grader identifiers.
write · /app/dut.sv
module TopModule (
    input  wire        clk,
    input  wire        rst,
    input  wire        op_valid_i,
    input  wire [1:0]  op_class_i,
    input  wire [1:0]  op_rd_i,
    input  wire [15:0] op_data_i,
    input  wire        c2_done_i,
    output wire        op_accept_o,
    output reg         wb_valid_o,
    output reg  [1:0]  wb_rd_o,
    output reg  [15:0] wb_data_o,
    output wire        c2_busy_o,
    output reg  [3:0]  inflight_o
);

    // Per-class slots
    reg        s0_valid;
    reg [1:0]  s0_rd;
    reg [15:0] s0_data;

    reg        s1_valid;
    reg        s1_ready;   // becomes ready one cycle after store (2 cycles after accept)
    reg [1:0]  s1_rd;
    reg [15:0] s1_data;

    reg        s2_valid;
    reg        s2_ready;   // sticky once c2_done seen while busy
    reg [1:0]  s2_rd;
    reg [15:0] s2_data;

    // -------- Combinational accept --------
    wire dest_free  = ~inflight_o[op_rd_i];
    wire slot_empty = (op_class_i == 2'd0) ? ~s0_valid :
                      (op_class_i == 2'd1) ? ~s1_valid :
                      (op_class_i == 2'd2) ? ~s2_valid : 1'b0;

    wire accept  = ~rst & op_valid_i & (op_class_i != 2'd3) & dest_free & slot_empty;
    wire accept0 = accept & (op_class_i == 2'd0);
    wire accept1 = accept & (op_class_i == 2'd1);
    wire accept2 = accept & (op_class_i == 2'd2);

    assign op_accept_o = accept;
    assign c2_busy_o   = ~rst & s2_valid;

    // -------- Readiness and writeback selection --------
    wire ready0 = s0_valid;
    wire ready1 = s1_valid & s1_ready;
    wire ready2 = s2_valid & s2_ready;

    wire sel0 = ready0;
    wire sel1 = ready1 & ~ready0;
    wire sel2 = ready2 & ~ready0 & ~ready1;

    // -------- Combinational writeback outputs --------
    always @* begin
        wb_valid_o = 1'b0;
        wb_rd_o    = 2'b00;
        wb_data_o  = 16'h0000;
        if (~rst) begin
            if (sel0) begin
                wb_valid_o = 1'b1;
                wb_rd_o    = s0_rd;
                wb_data_o  = s0_data;
            end else if (sel1) begin
                wb_valid_o = 1'b1;
                wb_rd_o    = s1_rd;
                wb_data_o  = s1_data;
            end else if (sel2) begin
                wb_valid_o = 1'b1;
                wb_rd_o    = s2_rd;
                wb_data_o  = s2_data;
            end
        end
    end

    // -------- Sequential state --------
    reg [3:0] inflight_next;
    always @* begin
        inflight_next = inflight_o;
        if (accept) inflight_next[op_rd_i] = 1'b1;
        if      (sel0) inflight_next[s0_rd] = 1'b0;
        else if (sel1) inflight_next[s1_rd] = 1'b0;
        else if (sel2) inflight_next[s2_rd] = 1'b0;
    end

    always @(posedge clk) begin
        if (rst) begin
            s0_valid  <= 1'b0;
            s0_rd     <= 2'b00;
            s0_data   <= 16'h0000;
            s1_valid  <= 1'b0;
            s1_ready  <= 1'b0;
            s1_rd     <= 2'b00;
            s1_data   <= 16'h0000;
            s2_valid  <= 1'b0;
            s2_ready  <= 1'b0;
            s2_rd     <= 2'b00;
            s2_data   <= 16'h0000;
            inflight_o <= 4'b0000;
        end else begin
            // slot 0
            if (accept0) begin
                s0_valid <= 1'b1;
                s0_rd    <= op_rd_i;
                s0_data  <= op_data_i + 16'd1;
            end else if (sel0) begin
                s0_valid <= 1'b0;
            end

            // slot 1
            if (accept1) begin
                s1_valid <= 1'b1;
                s1_ready <= 1'b0;
                s1_rd    <= op_rd_i;
                s1_data  <= op_data_i << 1;
            end else if (sel1) begin
                s1_valid <= 1'b0;
                s1_ready <= 1'b0;
            end else if (s1_valid & ~s1_ready) begin
                s1_ready <= 1'b1;
            end

            // slot 2
            if (accept2) begin
                s2_valid <= 1'b1;
                s2_ready <= 1'b0;
                s2_rd    <= op_rd_i;
                s2_data  <= op_data_i ^ 16'hffff;
            end else if (sel2) begin
                s2_valid <= 1'b0;
                s2_ready <= 1'b0;
            end else if (s2_valid & c2_done_i) begin
                s2_ready <= 1'b1;
            end

            inflight_o <= inflight_next;
        end
    end

endmodule
I've written `/app/dut.sv`. Key design decisions mapping to the spec: **Accept (combinational):** `op_accept_o` is high exactly when `op_valid_i`, the class isn't 3, the destination bit `inflight_o[op_rd_i]` is clear (using **registered** inflight), and the target class slot is empty. On the accepting edge the slot is stored and its inflight bit set. **Per-class writeback timing:** - **Class 0:** stored value `op_data_i+1`; `s0_valid` becomes 1 the cycle after accept, so it's ready and writes back exactly one cycle after accept. - **Class 1:** stored value `op_data_i*2` (`<<1`); an aging bit `s1_ready` sets one cycle after store, making the writeback fire two cycles after accept. - **Class 2:** stored value `op_data_i ^ 0xffff`; `s2_ready` sets on any edge where the slot is busy and `c2_done_i` is high, and is **sticky** until writeback. `c2_busy_o = s2_valid` , high while occupied, including the cycle of the writeback edge. **Single writeback / priority:** combinational selection `sel0 > sel1 > sel2`; only the winner pulses `wb_valid_o` for one cycle, frees its slot on that edge, and clears its inflight bit. Blocked ready slots retain their ready state (not dropped, not re-aged). **No accept/writeback bit collision:** an accept requires `inflight_o[op_rd_i]=0` while a writeback clears a currently-set bit, so set and clear can never hit the same bit on one edge. **Reset:** synchronous, clears all slots and `inflight_o`; the combinational outputs (`op_accept_o`, `c2_busy_o`, `wb_*`) are all gated to 0 during reset. The design uses only synthesizable constructs , no file I/O, DPI, force/release, or preprocessor directives.
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
TEST dut_present: PASS (/app/dut.sv exists)
TEST dut_forbidden: PASS (no forbidden constructs)
TEST dut_standalone: PASS (DUT elaborates standalone)
TEST harness_prepare: PASS (harness names nonce-renamed)
TEST dut_compiles: PASS (compiled with held-back reference/testbench)
TEST simulation_completed: PASS (Mismatches: 363 in 1093 samples)
TEST reference_equivalence: FAIL (363 mismatches in 1093 samples)

Reproduce this trial: git checkout 2f94510 && PYTHONPATH=src python3 scripts/build_site.py , then open trial/trial_03c1805bc6b94332. Re-running the agent live requires EVAL_PLATFORM_ENABLE_OAUTH_SMOKE=1 and is non-deterministic.

Trial trial_03c1805bc6b94332 · verifier authoritative; classifier explanatory.