refactor: Migrate table column ComponentRow.text from TEXT to MEDIUMTEXT length

[yuechao-qin]

Migrate component.text from TEXT to MEDIUMTEXT

What

Widens the component.text column from TEXT (64 KB) to MEDIUMTEXT (16 MB) on MySQL. PostgreSQL and SQLite are unaffected (TEXT is already unlimited).

Why

Component YAML specs can exceed 64 KB for complex pipelines with many parameters/outputs. The current TEXT limit silently truncates on MySQL.

How

• Model update: ComponentRow.text now uses sql.Text(length=2**24) which SQLAlchemy maps to MEDIUMTEXT on MySQL
• Migration function: migrate_component_text_column() in database_migrations.py — idempotent, inspects actual column length before deciding to ALTER
• Startup wiring: Runs automatically on deploy (after migrate_secret_value_column), no-op on subsequent deploys

Production impact

Factor	Value
Rows	13,702
Table size	~240 MB
MySQL algorithm	INPLACE
Estimated time	5–30 seconds
Concurrent DML	Allowed (reads/writes continue)
Lock	Brief metadata lock at start/end only

Testing

• 2 new unit tests: idempotency + large text round-trip (SQLite)
• All 56 existing tests pass

Files changed

File	Change
cloud_pipelines_backend/backend_types_sql.py	Add _MEDIUMTEXT_LENGTH constant
cloud_pipelines_backend/component_library_api_server.py	Update column type
cloud_pipelines_backend/database_migrations.py	Add migration function
cloud_pipelines_backend/database_ops.py	Wire into startup
cloud_pipelines_backend/api_router.py	Add 3 temporary admin endpoints
tests/test_database_migrations.py	Add 2 tests

Before merging

Remove the temporary admin endpoints at the bottom of api_router.py (marked with DO NOT MERGE INTO master/main banner).

[yuechao-qin]

• refactor: Migrate table column ComponentRow.text from TEXT to MEDIUMTEXT length #300 👈 (View in Graphite)
• master

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