fix(create): make --defaults create a harness project

[aidandaly24]

Description

Harness is now the default for agentcore create, so --defaults no longer creates a Python/Strands/Bedrock agent — it produces a harness project, identical to passing no routing flags.

This PR makes the code and docs reflect that:

• command.tsx — drop the agent-default backfill block that ran when --defaults was combined with an agent-path flag (e.g. --defaults --framework Strands). The flag is now purely "create with default (harness) settings." Update the help text from "Use defaults (Python, Strands, Bedrock, no memory)" to "Create a harness project with default settings (this is the default)."
• Docs — every --defaults usage is corrected:
  • Standalone harness quick-starts drop the flag (harness is implicit) and add an explicit agent example where useful (docs/commands.md).
  • Agent-oriented flows (gateway.md, knowledge-bases.md, payments.md, config-bundles.md, recommendations.md) now use the explicit --framework Strands --model-provider Bedrock agent path. This also fixes the two --defaults --with-config-bundle examples, which were silently broken — the harness path ignores --with-config-bundle, so they previously produced a harness with no bundle.
• Tests — strengthen the --defaults unit test to assert the harness contract (harnessName + app/<name>/harness.json) so the routing can't silently regress.

Related Issue

Closes #

Documentation PR

N/A — docs in this repo are updated in-line.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Other (please describe):

Testing

How have you tested the change?

• I ran npm run test:unit and npm run test:integ (ran the affected create unit + create-edge-cases integ suites — all pass)
• I ran npm run typecheck
• I ran npm run lint
• If I modified src/assets/, I ran npm run test:update-snapshots and committed the updated snapshots (no asset changes)

Checklist

• I have read the CONTRIBUTING document
• I have added any necessary tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

---

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[github-actions]

Package Tarball

aws-agentcore-0.21.0.tgz

How to install

gh release download pr-1644-tarball --repo aws/agentcore-cli --pattern "*.tgz" --dir /tmp/pr-tarball
npm install -g /tmp/pr-tarball/aws-agentcore-0.21.0.tgz

[agentcore-devx-automation]

Claude Security Review: no high-confidence findings. (run)

[agentcore-cli-automation]

Looks good to merge.

This is a focused, well-scoped change:

• Removing the agent-default backfill correctly reflects the new harness-default semantics for agentcore create. --defaults is now purely "create with default (harness) settings," matching the no-flags path.
• All doc updates are correct: agent-oriented flows (gateway, KB, payments, config bundles, recommendations) now use the explicit --framework Strands --model-provider Bedrock agent path, which also fixes the previously-broken --defaults --with-config-bundle examples (harness path silently ignored --with-config-bundle).
• The strengthened unit test asserts the harness contract (harnessName + app/<name>/harness.json) so the routing can't silently regress.
• Telemetry is unaffected — both the harness path (withCommandRunTelemetry) and agent path (runCliCommand) instrument as before.

One minor behavioral note (not blocking): mixing --defaults with a single agent-path flag like --framework Strands now triggers the standard "provide all: --framework, --model-provider, --memory" validation error instead of being backfilled. This is the intended behavior per the PR description, and the resulting error is clear enough to guide users.

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	37.42%	13771 / 36794
🔵	Statements	36.7%	14646 / 39904
🔵	Functions	32%	2356 / 7362
🔵	Branches	31.48%	9180 / 29161

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