#!/usr/bin/env bash
# Run one task through pi in a brand-new, zero-context session.
#
# Usage:
#   scripts/run-task.sh 0.1
#   scripts/run-task.sh 0.1 --dry-run     # print the prompt, run nothing
#
# Each invocation is a fresh pi session (--no-session). Nothing carries over between
# tasks; that is the point. See tasks/AGENT-PROMPT.md.

set -euo pipefail

REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
cd "$REPO_ROOT"

TASK_ID="${1:-}"
DRY_RUN="${2:-}"

if [[ -z "$TASK_ID" ]]; then
  echo "usage: scripts/run-task.sh <task-id> [--dry-run]" >&2
  echo "example: scripts/run-task.sh 0.1" >&2
  exit 2
fi

# Resolve the task file from its id prefix.
shopt -s nullglob
matches=(tasks/"$TASK_ID"-*.md)
shopt -u nullglob

if [[ ${#matches[@]} -eq 0 ]]; then
  echo "no task file found for id '$TASK_ID'" >&2
  echo "available:" >&2
  ls tasks/[0-9]*.md | sed 's|tasks/|  |' >&2
  exit 1
fi
if [[ ${#matches[@]} -gt 1 ]]; then
  echo "ambiguous task id '$TASK_ID' matches:" >&2
  printf '  %s\n' "${matches[@]}" >&2
  exit 1
fi

TASK_FILE="$(basename "${matches[0]}")"

# Extract the prompt body from the fenced block in AGENT-PROMPT.md, then substitute.
PROMPT="$(
  awk '/^```$/{f=!f; next} f' tasks/AGENT-PROMPT.md \
    | sed -e "s|{{TASK_ID}}|$TASK_ID|g" -e "s|{{TASK_FILE}}|$TASK_FILE|g"
)"

if [[ -z "${PROMPT// }" ]]; then
  echo "failed to extract prompt template from tasks/AGENT-PROMPT.md" >&2
  exit 1
fi

if [[ "$DRY_RUN" == "--dry-run" ]]; then
  printf '%s\n' "$PROMPT"
  exit 0
fi

# Default: claude-haiku-4-5. 200K context, reliable tool calling, needs
# ANTHROPIC_API_KEY in the environment.
#
# The two homelab models were both evaluated and rejected as defaults on 2026-08-19:
#
#   reasoning     16384 context, and pi's compaction.reserveTokens defaults to 16384,
#                 so the compaction threshold computes to zero. pi also only evaluates
#                 auto-compaction at run boundaries, never mid-turn (earendil-works/pi
#                 issues 6339, 5512, 2871), so a tool loop grows unchecked until the
#                 provider rejects it. Separately, under tool_choice "auto" it returns
#                 tool_calls: [] and reasons in prose, which stalls an agent loop.
#
#   ornith:35b    131K context and correct auto tool calling -- viable, and the right
#                 local choice. Occupied by other work at time of writing.
#
# Switch with env vars:
#   PI_PROVIDER=homelab-ornith PI_MODEL=ornith:35b scripts/run-task.sh 0.1
#
PROVIDER="${PI_PROVIDER:-homelab-ornith}"
MODEL="${PI_MODEL:-ornith:35b}"

# One fresh session file per task. This still guarantees zero context -- each task gets
# its own new file and never reads another's -- while leaving the run inspectable:
#
#   pi --session .task-runs/sessions/<task>.jsonl          # open it
#   pi --export  .task-runs/sessions/<task>.jsonl out.html # render it
#
# --no-session would also give zero context, but persists nothing to look at afterwards.
SESSION_DIR=".task-runs/sessions"
mkdir -p "$SESSION_DIR"
SESSION_FILE="$SESSION_DIR/$TASK_ID.jsonl"
rm -f "$SESSION_FILE"

echo "task     : $TASK_ID  ($TASK_FILE)"
echo "model    : $PROVIDER/$MODEL"
echo "session  : $SESSION_FILE (fresh)"
echo

# --print is required, not cosmetic. Without it pi starts its interactive TUI;
# under run-all.sh stdout is a file and stdin may be /dev/null, so the TUI renders
# nothing until exit and can sit waiting for input that never comes. --approve
# trusts project-local files (AGENTS.md and friends) for this run, which would
# otherwise raise a prompt no one is there to answer.
exec pi --provider "$PROVIDER" --model "$MODEL" \
  --print --approve \
  --session "$SESSION_FILE" "$PROMPT"