feat(payment): add session and instrument mutations

[aidandaly24]

Description

Final CUD layer of the payment stack, following manager/connector mutations in #2280.

Adds:

• payment session create|delete
• payment instrument create|delete

Includes session expiry/spend inputs, embedded-wallet shorthand or JSON inputs,
and user/connector/instrument scope. Manager-ID resolution, balance, IAM
provisioning, and provider/connector management are inherited from the lower layers.

The split preserved the pre-split implementation 10e4dacf byte-for-byte,
including production, tests, fixtures, and README. A subsequent naming-only
follow-up renamed the shared manager-ARN preflight helper to withPaymentManagerArn.
The latest upstream sync is 4a235162. Wallet JSON/shorthand conflicts use
assertMutuallyExclusiveFlags from #2263 pairwise, preserving valid combinations
of network, email, and phone flags. The existing test table covers each conflict.
No additional test suites or features were introduced.
Read-only/interactive TUI remains a separate follow-up.

Related Issue

Closes #2272.

Documentation PR

N/A. README command tree and session creation example are included.

Type of Change

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

Testing

• RECORD=0 bun test: 3,367 passed across 236 files.
• bun run typecheck, bun run lint:check, bun run format:check
• bun run build, bun run secrets:check
• Exact pre-rename split-tree comparison against 10e4dacf; existing regression coverage preserved.
• Naming-only follow-up: 79 focused payment tests, typecheck, formatting, lint, and build passed.
• Linux, Windows, and macOS CI on 5a583e26: https://github.com/aws/agentcore-cli/actions/runs/34625566083

Uses the repository's Bun scripts rather than the npm scripts from the main-branch template.
No AWS resources were changed or live mutation fixtures re-recorded.

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

PR #2280 is the outstanding dependency.

---

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the
terms of your choice.

[agentcore-devx-automation]

AgentCore Harness Review

Verdict: Looks good

Nice, self-contained addition. The new create/delete handlers for payment session and payment instrument mirror existing patterns in the module cleanly:

• SDK enums are pinned with as const satisfies readonly ..., so a new PaymentInstrumentType, CryptoWalletNetwork, or Currency will surface as a compile-time diff.
• Validation is done up-front in the handlers (including the nice detail of rejecting --instrument-details alongside shorthand flags before touching stdin, which the test asserts via readableLength).
• max-spend is kept as a string all the way through to avoid float coercion; the tests explicitly cover "0" and "10.00" for that.
• Tests use fixture-based CoreClients and only spy at the SDK send boundary or at core.payment.* where needed to assert short-circuit behavior — no excessive mocking, and lifecycle tests round-trip create → get → delete → post-delete ResourceNotFoundException through a real Core.
• Wiring updates (session/index.tsx, instrument/index.tsx, payment.read.test.tsx command inventory, TestPaymentClient stubs, CorePaymentClient interface, WithPaymentManagerId inputs) are all consistent.

No serious issues to flag — LGTM to merge.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 93.26923% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.14%. Comparing base (c537d6e) to head (5a583e2).

Files with missing lines	Patch %	Lines
src/handlers/payment/instrument/delete/index.tsx	84.00%	8 Missing ⚠️
src/handlers/payment/instrument/create/index.tsx	95.37%	5 Missing ⚠️
src/handlers/payment/session/create/index.tsx	93.42%	5 Missing ⚠️
src/handlers/payment/session/delete/index.tsx	91.89%	3 Missing ⚠️

Additional details and impacted files

@@                        Coverage Diff                         @@
##           feat/payment-manager-connector    #2281      +/-   ##
==================================================================
- Coverage                           97.17%   97.14%   -0.03%     
==================================================================
  Files                                 599      603       +4     
  Lines                               40808    41119     +311     
==================================================================
+ Hits                                39656    39946     +290     
- Misses                               1152     1173      +21     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.