Feature: Generic disablement system for memory files and tools

[chubes4]

Problem

Two systems in Data Machine have the concept of "disabling" items at a scoped level:

1. Tools — AI steps can disable specific tools via disabled_tools in pipeline step config. The ConfigureStepModal has a tool toggle UI.
2. Memory files — Currently no way to disable/suppress memory files at the pipeline or flow level. Core memory files always inject. Pipeline/flow memory files are opt-in (additive), but there's no way to say "don't inject this file for this flow."

These are conceptually the same pattern: a set of available items, with scope-level overrides that suppress specific items.

Proposed

Abstract the disablement pattern into a generic system that both memory files and tools can use:

The pattern

Available items (global)  →  Scope overrides (disabled list)  →  Effective items

For tools:

All registered tools  →  disabled_tools on pipeline step  →  Tools sent to AI

For memory files:

Core + pipeline + flow memory files  →  disabled_memory_files on flow  →  Files injected

Implementation options

Option A: Generic DisabledItems config pattern

• Store disabled_memory_files in flow_config (like disabled_tools in step config)
• Directives check the disabled list before injecting
• UI pattern: same toggle/checkbox approach as tool disablement

Option B: Shared ScopeOverrides system

• A general-purpose system for "at scope X, disable items Y from set Z"
• Could be used by tools, memory files, and future features (handlers, providers, etc.)
• More ambitious but prevents reinventing the pattern each time

Key consideration

The disablement needs to work across priority boundaries:

• Core memory files inject at priority 20
• Pipeline memory files at 40
• Flow memory files at 45
• A flow-level disabled_memory_files config needs to suppress files injected by earlier priorities

This likely means the disablement check needs to happen at a coordination point (e.g., PromptBuilder) rather than in each individual directive. Or directives check a shared payload key.

Related

• Feature: Flow-scoped memory files #471 (flow-scoped memory files)
• Feature: Extensible core memory file registry #501 (extensible core memory file registry)
• ConfigureStepModal AIToolsSelector — existing tool disablement UI
• disabled_tools in pipeline step config — existing pattern