validate-bundle: detect tool-task + delegate co-residency (silent ~27K token/request duplication)

[marklicata]

Problem

validate-bundle-repo.yaml and the bundle-design-expert do not currently detect when tool-task and the modern delegate tool are co-resident in the same bundle or behavior. When both are loaded in the same session, the full agent catalog is serialized into each tool's description field independently — doubling the per-request catalog cost with zero added capability.

Found in amplifier-bundle-tech-bro-idealist's behaviors/product-management.yaml, where - module: tool-task was declared alongside the foundation-provided delegate. Measured cost: ~27K tokens of redundant agent catalog per request — charged before the user types anything.

Root cause

tool-task (legacy) and tool-delegate (modern replacement) both independently serialize the full registered agent catalog into their tool description field. Foundation's behaviors document these as mutually exclusive, but nothing in the bundle validation or authoring workflow surfaces a warning when both are present in the same composition.

From Foundation docs: "task is the legacy task tool — for legacy task tool, use the tasks behavior instead." They are documented as not meant to be co-resident, but the documentation lives in a behavior file, not in a validator.

Impact

Every consumer of a behavior or bundle that declares tool-task and runs inside a host session that already provides delegate (i.e., any modern Amplifier session) pays the full duplicate catalog cost silently. At typical agent registry sizes this is ~27K extra tokens per request.

Tokens are charged per-request, not per-session — this compounds over every turn.

Evidence

• amplifier-bundle-tech-bro-idealist behaviors/product-management.yaml had - module: tool-task on line 25 alongside foundation-provided delegate. Fixed in that repo (commit 34ccf3a).
• amplifier_foundation/bundle_docs/token_cost.py already tracks all_tool_schemas with color thresholds — the infrastructure exists to surface this class of problem.

Requested changes

1. validate-bundle.yaml / validate-bundle-repo.yaml (in amplifier-foundation)
Add a check that flags tool-task and any delegate-equivalent tool as co-resident. Suggested failure message:

tool-task is the legacy agent-spawning module and is mutually exclusive with the delegate tool. Remove tool-task — PM agents are spawned by the host session's delegate tool.

2. bundle-design-expert guidance (in amplifier-foundation)
Add tool-task co-residency to the bundle anti-patterns knowledge. The expert should warn proactively during DESIGN and BUILD mode when an author adds tool-task to a bundle or behavior intended to compose into a modern Amplifier session.

3. token_cost.py thresholds (optional / bonus)
Consider whether duplicated agent-catalog tools should be surfaced as a distinct cost category in the token cost model, separate from legitimate tool schema cost.

Labels to add

bug, validate-bundle, token-cost, dx

[marklicata]

validate-bundle-repo should have caught this

Calling out the specific recipe that should have surfaced this:

amplifier-foundation/recipes/validate-bundle-repo.yaml runs as the standard validation gate when authoring or reviewing a bundle repo. It currently checks agent descriptions, context token costs, and bundle structure via validate-single-bundle.yaml — but it has no check for mutually exclusive tool modules.

The missing check is straightforward: scan the resolved tool module list for co-residency of tool-task and any delegate-equivalent module. If both are present, fail with an actionable message before the bundle ever ships to consumers.

This would have caught the behaviors/product-management.yaml case at authoring time — the redundant tool-task line existed in that behavior through multiple recipe iterations and commits (feat: upgrade product-1-pager recipe to v1.3.0, fix: bundle validation and context file hygiene) without any validator flagging it. The token duplication was silently compounding on every request the entire time.

Suggested addition to validate-single-bundle.yaml or validate-bundle-repo.yaml:

# Check: mutually exclusive tool modules
# tool-task is the legacy agent spawner. tool-delegate (provided by foundation)
# is its replacement. Both serialize the full agent catalog into their description
# field — co-residency doubles the catalog cost silently on every request.
- id: check-tool-task-delegate-coexistence
  description: Fail if tool-task and delegate are both declared in the same bundle/behavior
  fail_message: >
    tool-task is the legacy agent-spawning module and must not co-reside with the
    delegate tool. Remove "- module: tool-task" — agents are spawned by the host
    session's delegate tool. Co-residency serializes the full agent catalog twice
    per request (~27K+ tokens wasted before the user types anything).