fix(deploy): select the auto-detected target so a fresh project's first deploy isn't scoped to zero stacks

[jesseturner21]

Description

The very first interactive agentcore deploy on a freshly created project failed with:

Error: CDK deploy failed: Stack selection is ambiguous, please choose a specific stack for import [AgentCore-clitest-default]

Root cause: regression from the #1267 fix (#1659). The TUI deploy flow scopes its stack selector to the target picker's selection (PATTERN_MUST_MATCH over selectedTargets), and deliberately treats an empty selection as "deploy nothing" so the deploy-everything bug can't re-latent.

A fresh project has an empty aws-targets.json, so useAwsTargetConfig takes the auto-detect path: it detects the AWS account/region and saves a default target — but unlike the single-pre-configured-target and multi-target-picker paths, it never populated selectedTargetIndices. DeployScreen then passed selectedTargets = [] into the deploy flow, producing a pattern selector with zero patterns, and toolkit-lib threw NoStacksMatched. Second deploys worked (the target file was populated by then), so every first deploy of a new project was broken.

Fix: saveTarget() now also registers and selects the just-saved target, mirroring the existing single-target path:

setAvailableTargets([target]);
setSelectedTargetIndices([0]);

Related Issue

Closes #1752

Documentation PR

N/A — bug fix, no doc changes needed.

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
• 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

Additional verification:

• Reproduced before the fix: built the tarball with npm run bundle, installed it fresh, ran agentcore create --name clitest → agentcore deploy (interactive) — failed with the exact error above.
• New regression test src/cli/tui/hooks/__tests__/useAwsTargetConfig.test.tsx covering all three configuration paths (fresh-project auto-detect, lone pre-configured target, multi-target picker). The auto-detect case fails on the unfixed code and passes with the fix.
• Verified after the fix end-to-end: rebuilt the bundle, re-ran create → deploy against a real AWS account — deploy completed successfully (stack CREATE_COMPLETE, harness READY, deployed state persisted). Test stack cleaned up afterwards.
• All 806 TUI unit tests pass, including the 11 existing All targets are shown even if only 1 was selected #1267 target-scoping regression tests.

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

[agentcore-devx-automation]

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

[github-actions]

Package Tarball

aws-agentcore-0.24.0.tgz

How to install

gh release download pr-1753-tarball --repo aws/agentcore-cli --pattern "*.tgz" --dir /tmp/pr-tarball
npm install -g /tmp/pr-tarball/aws-agentcore-0.24.0.tgz

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	39.91%	14809 / 37101
🔵	Statements	39.17%	15782 / 40286
🔵	Functions	33.97%	2522 / 7423
🔵	Branches	33.41%	9863 / 29521

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