Port round-trip bug fixes from Python ZON PR#9 to TypeScript

[Copilot]

• Confirm top-level objects bypass _formatZonNode/_parseKey code paths
• Update boolean-keys.test.ts: wrap fixtures in { wrapper: {...} } so tests exercise the patched code paths
• Replaced broken mixed-key array test with a multi-sibling-object test
• All 311 tests pass

[ronibhakta1]

@coderabbitai look into this PR

[coderabbitai]

@ronibhakta1 Sure! I'll start reviewing this PR now. I'll look into the three round-trip bug fixes ported from the Python ZON implementation — boolean-like dictionary keys, dictionary header value quoting, and the associated test coverage. I'll post my findings shortly.

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[coderabbitai]

📝 Walkthrough

Walkthrough

This PR adds test coverage and implementation improvements for ZON encoding/decoding edge cases, including boolean-like dictionary keys and special characters in headers. A new parseKey utility function distinguishes key parsing from value parsing, with updates to encoder and decoder accordingly.

Changes

Cohort / File(s)	Summary
Test Coverage src/__tests__/boolean-keys.test.ts, src/__tests__/dict-header-quoting.test.ts	New Jest test suites validating encoding/decoding of boolean-like dictionary keys ("true", "false", "null", etc.) and dictionary headers containing commas and colons, ensuring round-trip preservation of original string keys and field values.
Key Parsing Utility src/core/utils.ts	Introduces parseKey function for ZON dictionary keys that always returns strings, supporting double-quoted and single-quoted keys, with ZON-to-JSON escape sequence conversion, without boolean/null keyword conversion.
Decoder Key Handling src/core/decoder.ts	Updates key parsing to use _parseKey instead of _parseValue, and enhances dictionary handling by splitting and parsing dictionary values with awareness of quotes and nesting.
Encoder Key Quoting src/core/encoder.ts	Adds quoting of object keys that resemble boolean/null keywords (true/false/t/f/null/none/nil, case-insensitive) to prevent misinterpretation; formats dictionary string values via _formatValue before emission.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 Keys and values, quite the pair!
We parse them with the utmost care.
No more "true" masquerading as a fact,
Each quoted key stays on its track.
Boolean-like keys now round-trip true,
The ZON encoder/decoder's breakthrough! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main objective of the PR: porting round-trip bug fixes from the Python ZON implementation to TypeScript, which aligns with the substantial changes across encoder, decoder, and utilities.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
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.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch copilot/sync-with-other-package

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[coderabbitai]

🧹 Nitpick comments (1)

src/__tests__/boolean-keys.test.ts (1)

12-98: Broaden these cases to hit the new parser path.

The top-level scalar fixtures still serialize through metadata lines, so they won't fail if _formatZonNode / _parseKey regresses. Consider moving the boolean-like keys under an object-valued property, or into an array-of-objects fixture, so these tests actually cover the fix.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@src/__tests__/boolean-keys.test.ts` around lines 12 - 98, The tests currently
encode top-level scalar objects so they bypass the new parser path; change each
fixture to place the boolean-like keys inside an object-valued property (e.g.
const data = { wrapper: { f: 1 } }) or into an array of objects (e.g. const data
= { items: [{ f: 1 }] }) so encode/decode passes through the zone-node
formatting/parsing code paths (those exercised by _formatZonNode / _parseKey);
update the assertions to inspect decoded.wrapper.f or decoded.items[0].f (and
corresponding keys like 'true','false','null') and adjust the case-variant loop
and multi-key test similarly so they validate nested/object-array decoded values
instead of top-level keys.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@src/__tests__/boolean-keys.test.ts`:
- Around line 12-98: The tests currently encode top-level scalar objects so they
bypass the new parser path; change each fixture to place the boolean-like keys
inside an object-valued property (e.g. const data = { wrapper: { f: 1 } }) or
into an array of objects (e.g. const data = { items: [{ f: 1 }] }) so
encode/decode passes through the zone-node formatting/parsing code paths (those
exercised by _formatZonNode / _parseKey); update the assertions to inspect
decoded.wrapper.f or decoded.items[0].f (and corresponding keys like
'true','false','null') and adjust the case-variant loop and multi-key test
similarly so they validate nested/object-array decoded values instead of
top-level keys.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 28649438-7a7e-46bc-a7af-8000e6ec5b5c

📥 Commits

Reviewing files that changed from the base of the PR and between 1b5917d and e60b76d.

⛔ Files ignored due to path filters (1)

• package-lock.json is excluded by !**/package-lock.json

📒 Files selected for processing (5)

• src/__tests__/boolean-keys.test.ts
• src/__tests__/dict-header-quoting.test.ts
• src/core/decoder.ts
• src/core/encoder.ts
• src/core/utils.ts