[trajectory-grader] Implement event-entropy-rate

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Caution

Protected files were modified in this change.
This pull request is in request_review mode and requires explicit human scrutiny before merge.

Protected files: README.md, .github/workflows/shared/graders/README.md, .github/workflows/shared/graders/event-entropy-rate.md

Implements event-entropy-rate (Tier 1, rank 10) from the trajectory graders catalog, 6 of 25 catalog graders implemented.

What it computes

Normalized first-order (bigram, previous-symbol-conditioned) Shannon entropy rate H(X_t | X_{t-1}) of the ordered canonical event symbol sequence, projected purely from the Trajectory IR's events[]. tool_call events are qualified by their ref (finer alphabet granularity); other events use their kind. Normalized by log2(alphabetSize) to stay in [0, 1] and remain comparable across traces with different event alphabets.

Why it's distinct from existing built-in graders

Built-in graders (tool-success-rate, retries, loops, trajectory-efficiency, execution-step-count, execution-duration) measure counts, durations, and success ratios but not information-theoretic diversity/unpredictability of the event process. event-entropy-rate differs from a raw distinct-event-kind count and from the existing recurrence graders (recurrence-rate, recurrence-determinism, recurrence-laminarity, recurrence-trapping-time, all revisit-density/structure-based) by measuring conditional unpredictability: a trace bouncing unpredictably between few event kinds can score higher than one with many kinds arranged in a strict repeating cycle.

Required IR fields

Only events[] — specifically event.index (or array position), event.kind, and optionally event.ref for tool-call qualification. No states, provenance, or objectives required, matching its Tier 1 "event sequence only" runtime requirement.

Catalog update

Flipped event-entropy-rate's status from Not started to Implemented in shared/graders/README.md. See that file for the full catalog and remaining graders.

Generated by 🧮 Daily Trajectory Grader Implementer · copilot · auto · 58.5 AIC · ⌖ 7.6 AIC · ⊞ 10.2K · ◷

• expires on Sep 10, 2026, 4:34 PM UTC-08:00

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Note

This was originally intended as a pull request, but the git push operation failed.

Original error: The process '/usr/bin/git' failed with exit code 1

Workflow Run: View run details and download bundle artifact

The bundle file is available in the agent artifact in the workflow run linked above.

Create the pull request manually

# Download the artifact from the workflow run
gh run download '33129779219' -n agent -D '/tmp/agent-33129779219'

# Resolve the bundle source ref, fetch it into a temporary ref, then create the local branch
bundle_path='/tmp/agent-33129779219/aw-trajectory-grader-event-entropy-rate.bundle'
temp_ref='refs/bundles/create-pr-trajectory-grader-event-entropy-rate-bfadf4a5d7f44396-6c61d0e7'
target_ref='refs/heads/trajectory-grader-event-entropy-rate-bfadf4a5d7f44396'
bundle_source_ref=$(git bundle list-heads "$bundle_path" | awk '$2 ~ /^refs\/heads\// { print $2 }')
if [ -z "$bundle_source_ref" ]; then
  bundle_source_ref=$(git bundle list-heads "$bundle_path" | awk '$2 == "HEAD" { print $2 }')
fi
if [ "$(printf '%s\n' "$bundle_source_ref" | sed '/^$/d' | wc -l | tr -d ' ')" != "1" ]; then
  echo "Expected exactly one bundle source ref, found: $bundle_source_ref" >&2
  exit 1
fi
git fetch "$bundle_path" "${bundle_source_ref}:${temp_ref}"
git update-ref "$target_ref" "$temp_ref"
git checkout 'trajectory-grader-event-entropy-rate-bfadf4a5d7f44396'
# Ensure the working tree matches the updated branch
git reset --hard
# Remove the temporary bundle ref
git update-ref -d "$temp_ref"

# Push the branch to the target remote
git push 'origin' 'trajectory-grader-event-entropy-rate-bfadf4a5d7f44396'

# Create the pull request
gh pr create --title '[trajectory-grader] Implement event-entropy-rate' --base 'main' --head 'trajectory-grader-event-entropy-rate-bfadf4a5d7f44396' --repo 'github/gh-aw'