Add regression-range hackbot agent (mozregression --prompt bisection)

agents/regression-range/Dockerfile

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+FROM python:3.12 AS builder
+
+COPY --from=ghcr.io/astral-sh/uv:latest /uv /uvx /bin/
+
+ENV UV_PROJECT_ENVIRONMENT=/opt/venv
+
+WORKDIR /app
+
+# Install external deps without building workspace members.
+RUN --mount=type=cache,target=/root/.cache/uv \
+    --mount=type=bind,source=pyproject.toml,target=pyproject.toml \
+    --mount=type=bind,source=uv.lock,target=uv.lock \
+    --mount=type=bind,source=VERSION,target=VERSION \
+    uv sync --frozen --no-dev --no-install-workspace --package hackbot-agent-regression-range
+
+RUN --mount=type=cache,target=/root/.cache/uv \
+    --mount=type=bind,target=/app,rw \
+    uv sync --locked --no-dev --no-editable --package hackbot-agent-regression-range
+
+# mozregression is installed from the fork carrying PR #2197 (the --prompt mode
+# is not yet in a release), so it lives outside the workspace lockfile. Pin to a
+# specific commit once the PR settles; the branch tracks the PR for now.
+ARG MOZREGRESSION_REF="git+https://github.com/msujaws/mozregression.git@prompt-devtools-mcp-verdict"
+RUN --mount=type=cache,target=/root/.cache/uv \
+    uv pip install --python /opt/venv "mozregression @ ${MOZREGRESSION_REF}"
+
+FROM python:3.12 AS base
+
+COPY --from=builder /opt/venv /opt/venv
+WORKDIR /app
+
+ENV PYTHONUNBUFFERED=1
+ENV PYTHONDONTWRITEBYTECODE=1
+ENV PATH="/opt/venv/bin:$PATH"
+
+FROM base AS agent
+
+# mozregression's --prompt mode (mozilla/mozregression#2197) shells out to the
+# Claude CLI, which launches the Firefox DevTools MCP via npx to classify each
+# build. So the agent image needs Node.js/npm/npx, the DevTools MCP, the Claude
+# CLI, and the shared libraries a downloaded Firefox needs to run headless. The
+# Firefox builds themselves are fetched by mozregression at bisect time.
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends \
+        # Node.js/npm/npx: run the Claude CLI and the Firefox DevTools MCP.
+        nodejs npm \
+        ca-certificates \
+        # Firefox runtime deps (for the builds mozregression downloads).
+        libgtk-3-0 libdbus-glib-1-2 libx11-xcb1 libxtst6 libxt6 libpci3 \
+        libnss3 libnspr4 libasound2t64 libpango-1.0-0 libcairo2 \
+        fonts-liberation \
+    && rm -rf /var/lib/apt/lists/*
+
+# The Claude CLI (invoked by mozregression --prompt) and the Firefox DevTools
+# MCP it drives. mozregression launches the MCP with `npx --prefer-offline
+# @mozilla/firefox-devtools-mcp`, so a global install keeps the run offline and
+# fast (npx resolves the globally-installed package before hitting the network).
+RUN npm install -g @anthropic-ai/claude-code @mozilla/firefox-devtools-mcp
+
+# hackbot.toml lives at the agent root (not inside the package), so copy it into
+# the working dir; the runtime discovers it there (cwd) at startup.
+COPY agents/regression-range/hackbot.toml /app/hackbot.toml
+
+RUN useradd --create-home --shell /bin/bash agent \
+    && mkdir -p /workspace \
+    && chown agent:agent /workspace
+
+USER agent
+
+CMD ["python", "-m", "hackbot_agents.regression_range"]
+
+FROM base AS broker
+
+RUN useradd --create-home --shell /bin/bash broker
+
+USER broker
+
+EXPOSE 8765
+
+CMD ["python", "-m", "hackbot_agents.regression_range.broker"]

agents/regression-range/compose.yml

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+services:
+  regression-range-broker:
+    build:
+      context: ../..
+      dockerfile: agents/regression-range/Dockerfile
+      target: broker
+    environment:
+      BUGZILLA_API_URL: ${BUGZILLA_API_URL}
+      BUGZILLA_API_KEY: ${BUGZILLA_API_KEY}
+    expose:
+      - "8765"
+
+  regression-range-agent:
+    build:
+      context: ../..
+      dockerfile: agents/regression-range/Dockerfile
+      target: agent
+    environment:
+      - RUN_ID
+      - BUG_ID=${BUG_ID:?error}
+      - GOOD=${GOOD:-}
+      - BAD=${BAD:-}
+      - BUGZILLA_MCP_URL=http://regression-range-broker:8765/mcp
+      - ANTHROPIC_API_KEY=${ANTHROPIC_API_KEY:?error}
+      # No uploader locally: summary/logs/attachments are written under
+      # /artifacts/<run_id>, bind-mounted to the host's ~/hackbot/artifacts so
+      # compose and direct runs land in the same user-scoped location.
+      - ARTIFACTS_DIR=/artifacts
+    volumes:
+      - ${HOME}/hackbot/artifacts:/artifacts
+    depends_on:
+      regression-range-broker:
+        condition: service_started

agents/regression-range/hackbot.toml

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+# This agent declares no [source] and no [firefox] table: it never needs a
+# Firefox source checkout or a local build. mozregression downloads the builds
+# it bisects, and its --prompt mode launches them through the Firefox DevTools
+# MCP. All the agent needs from the platform is Anthropic credentials (provided
+# automatically) and the brokered Bugzilla MCP (wired via env).

agents/regression-range/hackbot_agents/regression_range/__main__.py

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+from hackbot_runtime import HackbotContext, run_async
+from pydantic import field_validator
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+from .agent import RegressionRangeResult, run_regression_range
+
+
+class AgentInputs(BaseSettings):
+    bug_id: int
+    bugzilla_mcp_url: str
+    # Optional bisection bounds (date, version number, or changeset). When
+    # omitted, the agent infers them from the bug.
+    good: str | None = None
+    bad: str | None = None
+    model: str | None = None
+    # Model the nested mozregression --prompt agent uses; defaults to `model`.
+    mozregression_model: str | None = None
+    max_turns: int | None = None
+    effort: str | None = None
+
+    model_config = SettingsConfigDict(extra="ignore")
+
+    @field_validator(
+        "good", "bad", "model", "mozregression_model", "effort", mode="before"
+    )
+    @classmethod
+    def _empty_to_none(cls, v: object) -> object:
+        # compose passes optional inputs as empty strings when unset; treat those
+        # as absent so the agent infers bounds / uses defaults.
+        if isinstance(v, str) and not v.strip():
+            return None
+        return v
+
+
+async def main(ctx: HackbotContext) -> RegressionRangeResult:
+    inputs = AgentInputs()
+
+    return await run_regression_range(
+        bugzilla_mcp_server={
+            "type": "http",
+            "url": inputs.bugzilla_mcp_url,
+        },
+        bug=inputs.bug_id,
+        anthropic_api_key=ctx.anthropic.api_key,
+        good=inputs.good,
+        bad=inputs.bad,
+        model=inputs.model,
+        mozregression_model=inputs.mozregression_model,
+        max_turns=inputs.max_turns,
+        effort=inputs.effort,
+        log=ctx.log_path,
+        verbose=True,
+        actions_recorder=ctx.actions,
+    )
+
+
+if __name__ == "__main__":
+    run_async(main)