Fix current datetime propagation

[spboyer]

What

Updates the Squad coordinator and Scribe templates so spawned agents receive a resolved CURRENT_DATETIME value instead of unresolved placeholder text. Adds regression coverage and a patch changeset for the template behavior.

Why

Clean/new Squad sessions could carry {current_datetime} through spawn examples, leaving agents to infer or write the wrong day/time.

Fixes: #1119

How

The coordinator now resolves CURRENT_DATETIME once from <current_datetime>, sanity-checks it, and falls back to a local date command if the system value is missing or implausible. Date-bearing agent and Scribe examples now explicitly require substituting the literal received timestamp, and synced template mirrors keep init/upgrade output aligned.

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⚠️ Quick Check

• If SDK/CLI source files changed: completed the applicable Changeset step below (npx changeset add / .changeset/*.md, direct CHANGELOG.md entry for maintainers, or skip-changelog label for no user-facing changes)

PR Readiness Checklist

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Check each item before requesting review. See CONTRIBUTING.md for full details.

Branch & Commit

• Branch created from dev (not main)
• Branch is up to date with dev (git fetch upstream && git rebase upstream/dev)
• Verified diff contains only intended changes (git diff --cached --stat)
• PR is not in draft mode (mark ready when checks pass)
• Commit history is clean (squash fixups before review)

Build & Test

• npm run build passes
• npm test passes (all tests green)
• npm run lint passes (type check clean)
• npm run lint:eslint passes
• For migration PRs (>20 files): include test output summary in PR description

Changeset

• Changeset added via npx changeset add (if packages/squad-sdk/src/ or packages/squad-cli/src/ changed)
• Or direct CHANGELOG.md entry (maintainers only — write-protected for external contributors)
• Or skip-changelog label applied (if no user-facing changes)

Docs

N/A - this fixes generated coordinator/Scribe template behavior, not a new feature or docs page.

• README section updated (if new feature/module)
• Docs feature page (if new user-facing capability)

Exports

N/A - no SDK module exports changed.

• package.json subpath exports updated (if new module)

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Breaking Changes

None.

Waivers

N/A.

[Copilot]

Pull request overview

This PR updates Squad’s coordinator and Scribe templates to propagate a resolved current datetime value instead of unresolved placeholders, and adds regression coverage for that contract.

Changes:

• Adds CI coverage for datetime placeholder regressions in canonical templates.
• Updates coordinator spawn examples to pass a resolved CURRENT_DATETIME literal.
• Syncs Scribe datetime examples and mirrored template copies across CLI/SDK/root/GitHub agent locations.

Show a summary per file

File	Description
test/ci/datetime-template.test.ts	Adds regression checks for datetime propagation and placeholder usage.
.squad-templates/squad.agent.md	Updates canonical coordinator datetime resolution and spawn prompt guidance.
.squad-templates/scribe-charter.md	Updates canonical Scribe datetime examples.
templates/squad.agent.md.template	Mirrors coordinator template updates.
templates/scribe-charter.md	Mirrors Scribe charter updates.
packages/squad-cli/templates/squad.agent.md.template	Mirrors coordinator template updates for CLI package.
packages/squad-cli/templates/scribe-charter.md	Mirrors Scribe charter updates for CLI package.
packages/squad-sdk/templates/squad.agent.md.template	Mirrors coordinator template updates for SDK package.
packages/squad-sdk/templates/scribe-charter.md	Mirrors Scribe charter updates for SDK package.
.github/agents/squad.agent.md	Syncs GitHub agent copy with canonical coordinator template.
.changeset/fix-current-datetime-propagation.md	Adds patch changeset for CLI and SDK packages.

Copilot's findings

• Files reviewed: 11/11 changed files
• Comments generated: 5

[spboyer]

All review feedback from copilot-pull-request-reviewer has been addressed and CI is now passing. Ready for review — all 5 threads resolved, all checks green ✅