docs: reflect Cedar shipped alongside Rego as a peer backend

[boorad]

Summary

User-facing docs still framed PaC generation as Rego-only with Cedar "on the roadmap," but Cedar landed in v0.2 as a peer backend — src/cedar/ (generator, grouping, templates, validator via cedar-policy), extract --engine cedar, and engine-agnostic MCP tools (suggest_policy / validate_policy) are all live. This PR sweeps the stale "Rego today" / "OPA today" phrasings out of the README, AGENTS.md, Cargo.toml, and DESIGN.md, and flips the CEDAR_SUPPORT.md memo from "Draft — exploring for v0.3" to "Historical — shipped in v0.2".

Changes

• README.md — tagline, intro, extract CLI example, MCP framing; tools table now lists suggest_policy / validate_policy with suggest_rego / validate_rego called out as backward-compat aliases; dropped stale "seven tool descriptors" count
• AGENTS.md (CLAUDE.md symlink) — opening tagline; rules description now references both rego_template and cedar_template; split the engine module bullet into separate Rego and Cedar entries
• Cargo.toml — crate description field
• docs/DESIGN.md — vision, goals, pattern-rule template list, policy-generation section, EXTRACT CLI options (added --engine, renamed --package-prefix → --policy-prefix with the alias documented), EnforceAuth relationship section
• docs/CEDAR_SUPPORT.md — status banner flipped to "Historical — shipped in v0.2"; body preserved as the original scoping snapshot so the design narrative isn't lost

Each touched spot now names the AWS Verified Permissions / Arbiter / Cedar-compatible audience explicitly.

Test plan

• cargo build — sanity check that the Cargo.toml description edit parses
• Render README / DESIGN.md / CEDAR_SUPPORT.md on GitHub and skim for broken markdown or stale phrasing
• Confirm cargo publish --dry-run (if used in release-plz) accepts the new description string
• Visual diff review — pure docs change, no runtime impact

Follow-ups (filed separately)

• Structural scanner support for Kotlin #84 — Structural scanner support for Kotlin
• Structural scanner support for Ruby #85 — Structural scanner support for Ruby
• Structural scanner support for PHP #86 — Structural scanner support for PHP

🤖 Generated with Claude Code

Summary by CodeRabbit

• Documentation
  • Updated documentation to reflect policy generation support for both Rego (OPA) and Cedar (AWS Verified Permissions and other Cedar-compatible engines).
  • Clarified CLI options including --engine parameter for selecting policy backends.
  • Updated MCP tool descriptions with engine-agnostic naming conventions.
  • Marked Cedar support as shipped in v0.2.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 2dd3c72a-b49f-4557-abb8-f55a7f538e81

📥 Commits

Reviewing files that changed from the base of the PR and between 2863701 and 21085c8.

📒 Files selected for processing (5)

• AGENTS.md
• Cargo.toml
• README.md
• docs/CEDAR_SUPPORT.md
• docs/DESIGN.md

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📝 Walkthrough

Walkthrough

Documentation updates across package metadata, README, design documentation, and agent specifications to reflect that Zift generates Policy-as-Code for both Rego (OPA) and Cedar (AWS Verified Permissions and Cedar-compatible engines), with clarified CLI engine selection and Cedar recorded as shipped in v0.2.

Changes

Multi-engine scope and interface documentation

Layer / File(s)	Summary
Feature overview and scope documentation Cargo.toml, AGENTS.md, docs/DESIGN.md, README.md	Opening descriptions, package metadata, architecture notes, and Goals updated to explicitly state that Zift generates Policy-as-Code for both Rego (OPA) and Cedar (AWS Verified Permissions, Arbiter, and other Cedar-compatible engines).
CLI and MCP tool interface updates README.md, docs/DESIGN.md	extract command expanded with --engine (rego|cedar), --policy-prefix, and --output-dir options; MCP tools broadened from Rego-only suggest_rego/validate_rego to engine-agnostic suggest_policy/validate_policy with backward-compatible Rego aliases.
Policy template and shipped status updates docs/CEDAR_SUPPORT.md, docs/DESIGN.md, README.md	Pattern rule documentation now describes per-engine policy templates (Rego and Cedar); Cedar support status marked Historical with v0.2 shipped details; MCP smoke-test reference generalized to remove hardcoded tool count.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

Possibly related PRs

• EnforceAuth/zift#28: Continues the policy-as-code and Cedar backend documentation refactor by recording Cedar as shipped (v0.2) and further broadening design and MCP interface documentation to reflect active multi-engine support.

Poem

🐰 Cedar trees grow tall and proud,
Rego rules march through the cloud,
One extraction, engines two—
Policy templates see them through!
Authorization's brave new ✨ crew!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the main objective of the PR: updating documentation to show Cedar as a peer backend alongside Rego, which is confirmed by changes across README.md, DESIGN.md, CEDAR_SUPPORT.md, AGENTS.md, and Cargo.toml.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch chore/docs-rego-cedar-targets

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[amazon-q-developer]

This documentation PR accurately updates all references to reflect Cedar's shipped status in v0.2. The changes consistently sweep "Rego today" / "on the roadmap" phrasings across README, AGENTS.md, Cargo.toml, DESIGN.md, and flip CEDAR_SUPPORT.md to historical status. All updates align with the actual codebase state where src/cedar/, extract --engine cedar, and engine-agnostic MCP tools are live.

No defects blocking merge identified.

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