fix: bound Slack approval block text

[2001Y]

What does this PR do?

Bounds Slack approval Block Kit section text so approval buttons do not fail with Slack invalid_blocks errors when the command and/or approval reason is long.

The fix budgets the command preview and reason text together against Slack's 3000-character section.text.text limit. It keeps short reasons intact and only truncates the reason when the combined section would exceed Slack's limit.

Related Issue

N/A — observed Slack approval UI failure from oversized Block Kit section text.

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 🔒 Security fix
• 📝 Documentation update
• ✅ Tests (adding or improving test coverage)
• ♻️ Refactor (no behavior change)
• 🎯 New skill (bundled or hub)

Changes Made

• Keep Slack approval Block Kit section.text.text within Slack's 3000-character limit.
• Budget command and reason text together instead of truncating only the command preview.
• Preserve the approval reason when short and truncate it only when necessary.
• Add/keep regression coverage in tests/gateway/test_slack_approval_buttons.py for long approval text.

How to Test

1. Run the Slack approval regression tests:

   python -m pytest tests/gateway/test_slack_approval_buttons.py -q -o addopts=

2. Confirm the tests pass and the generated Slack approval block text remains under the limit for long command/reason inputs.

Latest local verification:

24 passed, 4 warnings in 0.91s

The warnings are existing async mock RuntimeWarnings in Slack thread-context tests and are not introduced by this PR.

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):, feat(scope):, etc.)
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix/feature (no unrelated commits)
• I've run pytest tests/ -q and all tests pass
• I've added tests for my changes (required for bug fixes, strongly encouraged for features)
• I've tested on my platform: macOS

Documentation and Housekeeping

• I've updated relevant documentation (README, docs/, docstrings) — or N/A
• I've updated cli-config.yaml.example if I added/changed config keys — or N/A
• I've updated CONTRIBUTING.md or AGENTS.md if I changed architecture or workflows — or N/A
• I've considered cross-platform impact (Windows, macOS) per the compatibility guide — or N/A
• I've updated tool descriptions/schemas if I changed tool behavior — or N/A

Screenshots / Logs

Targeted pytest output is included above. No UI screenshot; this is a Slack Block Kit payload-size guard.

[austinpickett]

Please use .github/PULL_REQUEST_TEMPLATE.md

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[2001Y]

Updated the PR body to the repository template and re-ran the targeted Slack approval regression suite.

python -m pytest tests/gateway/test_slack_approval_buttons.py -q -o addopts=
24 passed, 4 warnings in 0.91s

The linked Copilot reviews failed before producing inline comments, so there were no Copilot code items to address on this PR.

[teknium1]

Thanks for the Slack approval fix. This has since been implemented on main by a broader Slack approval UX fix, so I think this PR can be closed as already handled.

Evidence from this automated hermes-sweeper review:

• gateway/platforms/slack.py:2767 now explicitly accounts for Slack's 3000-character section block cap in send_exec_approval.
• gateway/platforms/slack.py:2774-2784 builds the rendered section text from a budgeted command preview plus bounded reason text, preventing the oversized invalid_blocks approval-card failure this PR targets.
• The change landed in cd9a9cd8e5e12daed968360f70d28e749c6c1fa0 via merged PR fix(gateway): Slack approval UX in threads — block-size overflow + typed-prefix instruction text #43444, whose body calls out the same root cause: long execute_code approval blocks overflowing Slack's 3000-character Block Kit limit.

The PR's discussion and the related #35495 cross-reference were useful in tracking the affected Slack approval path.