GitHub API Cache

Overview

Cache GitHub project metadata ONCE at session start. All subsequent operations use cached data.

Core principle: Fetch once, extract many. Never repeat API calls for the same data.

This skill is called by `session-start` and provides cached data to all other skills.

The Problem

GitHub GraphQL API has a 5,000 point/hour limit. Without caching:

• gh project item-list = 1 call per invocation
• gh project field-list = 1 call per invocation
• gh project list = 1 call per invocation

A typical session startup was consuming 3,500+ of 5,000 points through repeated calls.

The Solution

Fetch project metadata ONCE and cache in environment variables. All skills use cached data.

Rate Limit Check

Before any bulk operations, check available quota:

check_github_rate_limits() {
  local graphql_remaining=$(gh api rate_limit --jq '.resources.graphql.remaining')
  local graphql_reset=$(gh api rate_limit --jq '.resources.graphql.reset')
  local rest_remaining=$(gh api rate_limit --jq '.resources.core.remaining')

  echo "GraphQL: $graphql_remaining remaining"
  echo "REST: $rest_remaining remaining"

  if [ "$graphql_remaining" -lt 100 ]; then
    local now=$(date +%s)
    local wait_seconds=$((graphql_reset - now + 10))
    echo "WARNING: GraphQL rate limit low. Resets in $wait_seconds seconds."
    return 1
  fi
  return 0
}

Session Initialization (2 API Calls Total)

Run this ONCE at session start. Store results in environment.

# === GitHub API Cache Initialization ===
# Cost: 2 GraphQL API calls (field-list + item-list)

echo "Caching GitHub project metadata..."

# Verify environment
if [ -z "$GITHUB_PROJECT_NUM" ] || [ -z "$GH_PROJECT_OWNER" ]; then
  echo "ERROR: GITHUB_PROJECT_NUM and GH_PROJECT_OWNER must be set"
  exit 1
fi

# CALL 1: Cache all project fields
export GH_CACHE_FIELDS=$(gh project field-list "$GITHUB_PROJECT_NUM" --owner "$GH_PROJECT_OWNER" --format json)

# CALL 2: Cache all project items
export GH_CACHE_ITEMS=$(gh project item-list "$GITHUB_PROJECT_NUM" --owner "$GH_PROJECT_OWNER" --format json)

# Extract field IDs from cached data (NO API CALLS)
export GH_STATUS_FIELD_ID=$(echo "$GH_CACHE_FIELDS" | jq -r '.fields[] | select(.name == "Status") | .id')
export GH_TYPE_FIELD_ID=$(echo "$GH_CACHE_FIELDS" | jq -r '.fields[] | select(.name == "Type") | .id // empty')
export GH_PRIORITY_FIELD_ID=$(echo "$GH_CACHE_FIELDS" | jq -r '.fields[] | select(.name == "Priority") | .id // empty')

# Extract status option IDs from cached data (NO API CALLS)
export GH_STATUS_BACKLOG_ID=$(echo "$GH_CACHE_FIELDS" | jq -r '.fields[] | select(.name == "Status") | .options[] | select(.name == "Backlog") | .id')
export GH_STATUS_READY_ID=$(echo "$GH_CACHE_FIELDS" | jq -r '.fields[] | select(.name == "Status") | .options[] | select(.name == "Ready") | .id')
export GH_STATUS_IN_PROGRESS_ID=$(echo "$GH_CACHE_FIELDS" | jq -r '.fields[] | select(.name == "Status") | .options[] | select(.name == "In Progress") | .id')
export GH_STATUS_IN_REVIEW_ID=$(echo "$GH_CACHE_FIELDS" | jq -r '.fields[] | select(.name == "Status") | .options[] | select(.name == "In Review") | .id')
export GH_STATUS_DONE_ID=$(echo "$GH_CACHE_FIELDS" | jq -r '.fields[] | select(.name == "Status") | .options[] | select(.name == "Done") | .id')
export GH_STATUS_BLOCKED_ID=$(echo "$GH_CACHE_FIELDS" | jq -r '.fields[] | select(.name == "Status") | .options[] | select(.name == "Blocked") | .id')

# Get project ID (needed for item-edit) - extract from cached fields response
# Note: If project ID not available in fields, this requires 1 additional call
export GH_PROJECT_ID=$(gh project list --owner "$GH_PROJECT_OWNER" --format json --limit 100 | \
  jq -r ".projects[] | select(.number == $GITHUB_PROJECT_NUM) | .id")

echo "Cached: $(echo "$GH_CACHE_ITEMS" | jq '.items | length') project items"
echo "GraphQL calls used: 3"

Cached Data Access Functions

These functions use ONLY cached data. NO API calls.

Get Item ID from Issue Number

get_cached_item_id() {
  local issue_num=$1
  echo "$GH_CACHE_ITEMS" | jq -r ".items[] | select(.content.number == $issue_num) | .id"
}

Get Item Status from Issue Number

get_cached_status() {
  local issue_num=$1
  echo "$GH_CACHE_ITEMS" | jq -r ".items[] | select(.content.number == $issue_num) | .status.name"
}

Get Issues by Status

get_cached_issues_by_status() {
  local status=$1
  echo "$GH_CACHE_ITEMS" | jq -r ".items[] | select(.status.name == \"$status\") | .content.number"
}

Get All Items with Status

get_cached_items_summary() {
  echo "$GH_CACHE_ITEMS" | jq -r '.items[] | {number: .content.number, title: .content.title, status: .status.name}'
}

Check if Issue is in Project

is_issue_in_project() {
  local issue_num=$1
  local item_id=$(get_cached_item_id "$issue_num")
  [ -n "$item_id" ] && [ "$item_id" != "null" ]
}

Cache Refresh

Only refresh cache when you KNOW data has changed:

refresh_items_cache() {
  # Cost: 1 API call
  export GH_CACHE_ITEMS=$(gh project item-list "$GITHUB_PROJECT_NUM" --owner "$GH_PROJECT_OWNER" --format json)
  echo "Items cache refreshed"
}

Write Operations (Still Require API Calls)

Write operations cannot be cached. Use sparingly.

Set Project Status (1 API call)

set_status_cached() {
  local item_id=$1
  local status_option_id=$2  # Use GH_STATUS_*_ID variables

  gh project item-edit --project-id "$GH_PROJECT_ID" --id "$item_id" \
    --field-id "$GH_STATUS_FIELD_ID" --single-select-option-id "$status_option_id"
}

# Example: Set to "In Progress"
# set_status_cached "$ITEM_ID" "$GH_STATUS_IN_PROGRESS_ID"

Add Issue to Project (1 API call + cache refresh)

add_issue_to_project_cached() {
  local issue_url=$1

  gh project item-add "$GITHUB_PROJECT_NUM" --owner "$GH_PROJECT_OWNER" --url "$issue_url"

  # Refresh items cache after add
  refresh_items_cache
}

Anti-Patterns (NEVER DO)

Repeated Field Lookups

# WRONG: 3 API calls for same data
STATUS_FIELD=$(gh project field-list ... | jq '.fields[] | select(.name == "Status")')
TYPE_FIELD=$(gh project field-list ... | jq '.fields[] | select(.name == "Type")')
PRIORITY_FIELD=$(gh project field-list ... | jq '.fields[] | select(.name == "Priority")')

# RIGHT: 0 API calls (uses cached data)
STATUS_FIELD=$(echo "$GH_CACHE_FIELDS" | jq '.fields[] | select(.name == "Status")')
TYPE_FIELD=$(echo "$GH_CACHE_FIELDS" | jq '.fields[] | select(.name == "Type")')
PRIORITY_FIELD=$(echo "$GH_CACHE_FIELDS" | jq '.fields[] | select(.name == "Priority")')

Polling Item List in Loops

# WRONG: N API calls for N items
for issue in 1 2 3 4 5; do
  gh project item-list ... | jq ".items[] | select(.content.number == $issue)"
done

# RIGHT: 0 API calls (uses cached data)
for issue in 1 2 3 4 5; do
  echo "$GH_CACHE_ITEMS" | jq ".items[] | select(.content.number == $issue)"
done

Re-fetching Field IDs

# WRONG: API call every time you need to update status
STATUS_FIELD_ID=$(gh project field-list ... | jq -r '.fields[] | select(.name == "Status") | .id')

# RIGHT: Use cached environment variable
echo "$GH_STATUS_FIELD_ID"

REST API for Simple Operations

When you need data not in the cache, prefer REST API (separate rate limit):

# REST API - uses separate 5,000/hour limit
gh api "repos/$OWNER/$REPO/issues/$ISSUE_NUM"
gh api "repos/$OWNER/$REPO/issues/$ISSUE_NUM/comments"

# MCP tools also use REST
mcp__github__get_issue(...)
mcp__github__list_issues(...)

Environment Variables Reference

After initialization, these are available:

API Cost Summary

Integration

This skill is called by:

• session-start - Initializes cache at session start

This skill's cached data is used by:

• project-board-enforcement - All verification functions
• issue-driven-development - Status updates and checks
• issue-prerequisite - Adding issues to project
• epic-management - Epic operations
• autonomous-orchestration - State queries

Checklist

Before any GitHub project operation:

• [ ] Cache initialized (GH_CACHE_ITEMS exists and is not empty)
• [ ] Rate limit checked if bulk operation
• [ ] Using cached data for reads
• [ ] Only making API calls for writes
• [ ] Refreshing cache after writes that add items