Depends on #70424.

MD5-Based Incremental Script Seeding

Problem

Our CI system uses a cached build from the staging branch as a starting point. The seed process previously used a .seeded file as a timestamp marker - only .script_json files newer than .seeded would be re-seeded.

This approach causes drone to fail on PRs which add new scripts to UI_TEST_SCRIPTS. The cached .seeded file has a newer timestamp than the new script files, so they don't get seeded. This caused seed:courses_ui_tests to fail when trying to reference units that were never seeded. Here are two recent examples of this happening:

• drone failures blocked a PR from being merged: https://codedotorg.slack.com/archives/C046G4TRLEN/p1768343599212099
• DTT failed after UI_TEST_SCRIPTS was added to: Revert "seeding tools: write ui-test-only curriculum content files to custom location" #70341

Solution

Replace timestamp-based incremental seeding with MD5 hash-based seeding, following the existing pattern for level files:

• code-dot-org/dashboard/lib/level_loader.rb

  Lines 34 to 35 in 894d30f

  	Level.transaction do
  	level_md5s_by_name = Level.pluck(:name, :md5).to_h

• code-dot-org/dashboard/lib/tasks/seed.rake

  Lines 441 to 442 in 894d30f

  	def parse_dsl_files(dsl_files, dsl_types)
  	level_md5s_by_name = DSLDefined.pluck(:name, :md5).to_h

Changes:

• Add md5 column to scripts table to store the hash of each script's .script_json contents (done in add md5 column to scripts table via db migration #70424)
• Update update_scripts in seed.rake to compare file MD5 against stored hash instead of file timestamps
• Pass MD5 through the ScriptSeed call stack (seed_from_json_file → seed_from_json → seed_from_hash → import_script)
• Update write_script_json when levelbuilders update a script or lesson, to avoid triggering a redundant re-seed in levelbuilder env

Testing Story

CI Validation

Automated Tests

Added 4 unit tests:

In script_seed_test.rb:

• seed_from_json_file stores md5 when provided - verifies MD5 is stored in the database when passed through the seeding call stack
• seed_from_json_file works without md5 parameter - verifies backward compatibility when MD5 is not provided

In unit_test.rb:

• write_script_json updates md5 in levelbuilder mode - verifies levelbuilder writes MD5 field to match file contents
• write_script_json does nothing outside levelbuilder mode - verifies no-op behavior in non-levelbuilder environments

Performance

Benchmarked overhead of MD5 hashing and JSON parsing for all ~600 script files:

# MD5 hashing only (~0.6s)
Benchmark.measure { Dir.glob('config/scripts_json/*.script_json').each { |f| Digest::MD5.hexdigest(File.read(f)) } }
# => real=0.60s

# JSON parsing only (~0.8s)
Benchmark.measure { Dir.glob('config/scripts_json/*.script_json').each { |f| JSON.parse(File.read(f)) } }
# => real=0.82s

Total overhead of ~1.4s is acceptable compared to the 90+ seconds saved by not re-seeding unchanged scripts.