[trajectory-grader] Implement recurrence-trapping-time

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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/recurrence-trapping-time.md

Summary

Implements recurrence-trapping-time (Tier 1, rank 8) — the next grader in catalog order after state-revisit-probability-rep, recurrence-determinism, and recurrence-laminarity.

Grader: recurrence-trapping-time (RQA TT)

Computes the RQA "trapping time" metric: the mean length of vertical line structures (length ≥ 2) in the state-recurrence matrix built from the canonical state/event sequence. This measures the average number of consecutive steps an agent stays "trapped" once it starts re-entering a previously visited state.

Distinct from existing graders:

• Complements recurrence-laminarity (LAM), which measures the fraction of recurrent structure that is vertical (stagnation), by instead quantifying the typical duration of each stagnation episode.
• Distinct from built-in loop/retry graders, which don't use the RQA vertical-line-length formulation.
• Distinct from recurrence-determinism, which measures diagonal (ordered repeated subsequence) structure, not vertical (single-state stagnation) structure.

Required IR fields: canonical states[] (with id, optional firstEventIndex) and events[] (with index) from the Trajectory IR — same fields already consumed by recurrence-laminarity and recurrence-determinism.

Implementation notes:

• Follows the same candidate-resolution and state-ordering normalization used by recurrence-laminarity.md/recurrence-determinism.md.
• Returns a deterministic "not applicable" result when fewer than 4 canonical state visits exist, and a vacuous 0 when no vertical recurrence structures are found.
• Pure inline script; no network, no require/import, no nondeterminism.

Catalog update

Flipped recurrence-trapping-time status from Not started to Implemented in shared/graders/README.md. See shared/graders/README.md for the full catalog — 8 of 25 implemented.

Files changed

• .github/workflows/shared/graders/recurrence-trapping-time.md (new)
• .github/workflows/shared/graders/README.md (status flip only)

Generated by 🧮 Daily Trajectory Grader Implementer · copilot · auto · 56.2 AIC · ⌖ 7 AIC · ⊞ 10.2K · ◷

• expires on Sep 8, 2026, 8:38 AM 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 '32872112188' -n agent -D '/tmp/agent-32872112188'

# Resolve the bundle source ref, fetch it into a temporary ref, then create the local branch
bundle_path='/tmp/agent-32872112188/aw-daily-trajectory-grader-recurrence-trapping-time.bundle'
temp_ref='refs/bundles/create-pr-daily-trajectory-grader-recurrence-trapping-time-4baf20dcd0639179-e3510f7c'
target_ref='refs/heads/daily-trajectory-grader-recurrence-trapping-time-4baf20dcd0639179'
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 'daily-trajectory-grader-recurrence-trapping-time-4baf20dcd0639179'
# 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' 'daily-trajectory-grader-recurrence-trapping-time-4baf20dcd0639179'

# Create the pull request
gh pr create --title '[trajectory-grader] Implement recurrence-trapping-time' --base 'main' --head 'daily-trajectory-grader-recurrence-trapping-time-4baf20dcd0639179' --repo 'github/gh-aw'