Add orderbook to Financial

[intrepidkarthi]

Required links

• Forge link: https://github.com/intrepidkarthi/orderbook
• pkg.go.dev: https://pkg.go.dev/github.com/intrepidkarthi/orderbook
• goreportcard.com: https://goreportcard.com/report/github.com/intrepidkarthi/orderbook
• Coverage service link: not yet published to a coverage service. Measured at v0.26.0: 83.8% of statements over pkg/... and internal/..., 73.4% counting the cmd/ binaries and examples/ demos. codecov.yml and the upload step are committed; the repo is not activated on codecov.io yet, so I have not put a link here that would 404.

Pre-submission checklist

• I have read the Contribution Guidelines
• I have read the Quality Standards

Repository requirements

• The repo has a go.mod file and at least one SemVer release (vX.Y.Z) — v0.26.0
• The repo has an open source license — MIT
• The repo documentation has a pkg.go.dev link
• The repo documentation has a goreportcard link — removed deliberately: goreportcard.com was sunset on 1 July 2026 and gojp/goreportcard is archived. The badge endpoint now serves an SVG reading "go report: retired", so it was dropped from the README rather than left advertising a dead service. The report URL is still in the required-links block above.
• The repo documentation has a coverage service link — see above.
• The repo has a continuous integration process — GitHub Actions: build, vet, go test -race, benchmarks, and a nightly soak
• CI runs tests that must pass before merging

Pull Request content

• This PR adds only one package — the diff is a single line
• The package has been added in alphabetical order (after ofxgo and the existing orderbook, before payme)
• The link text is the exact project name
• The description is clear, concise, non-promotional, and ends with a period
• The link in README.md matches the forge link above

go test main_test.go main.go passes identically with and without this change — 4 pre-existing TestAlpha ordering errors on main, in Data stores with expiring records (easycache/echovault) and Libraries that are used to help make your application more secure (acme-proxy/acmetool), neither touched here.

Category quality

• The packages around my addition still meet the Quality Standards.

Checked the five nearest entries; all are live and none are archived: ofxgo (Feb 2026), orderbook — i25959341 (Apr 2025), payme (Jul 2026), paystack-sdk-go (Jun 2026), money — govalues (Jan 2025).

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About the package

An embeddable limit order book and matching engine. It works in int64 ticks and lots with no floating point on the money path, and a per-symbol Instrument converts decimals only at the API boundary.

• Single-writer core — one matching goroutine owns the book with no lock on the hot path (the LMAX model); a Runner fronts it with an MPSC queue for concurrent producers.
• Zero-allocation match path — Match into a caller-supplied buffer allocates 0 B/op.
• Deterministic and recoverable — the same ordered command stream produces byte-identical trades and book state, gated in CI against a 2,000-command tape; pkg/wal provides a checksummed write-ahead log with snapshots, segment rotation and retention.
• Full order surface — limit, market, stop / stop-limit, iceberg, post-only, pegged, OCO / bracket, trailing-stop; GTC / IOC / FOK / DAY / GTD.

Note on the duplicate name: there is already an orderbook in this section (i25959341/orderbook). They are different projects with the same package name, which the section already accommodates for decimal (three entries) and go-finance (two). Happy to rename the link text if you would rather disambiguate.

Disclosure: I'm the author of the project. It is explicit that it is an experiment rather than a product — it has never run a live market, and docs/PRODUCTION-READINESS.md is a written account of what it does not do.

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[github-actions]

Automated Quality Checks

Required checks

✅ Repo: accessible, has go.mod and SemVer release
✅ pkg.go.dev: OK
✅ Go Report Card: OK (grade unknown)

Additional checks

✅ License: MIT
✅ Maturity: repo has 5+ months of history
✅ CI/CD: GitHub Actions workflows detected
✅ README: present
⚠️ Coverage: missing from PR body

How to fix: Add a coverage service link to your PR description:

Coverage: https://app.codecov.io/gh/your-org/your-project

Popular options: [Codecov](https://codecov.io), [Coveralls](https://coveralls.io). Integrate one with your CI to track coverage automatically.


_These checks are automated and do not replace maintainer review. See [CONTRIBUTING.md](https://github.com/avelino/awesome-go/blob/main/CONTRIBUTING.md) for full guidelines._

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## PR Diff Validation

### Content checks

✅ **Files changed**: only README.md
✅ **Single item**: one package added
✅ **Link consistency**: README link matches forge link in PR body
✅ **Link text**: matches repository name
✅ **Description**: ends with punctuation
✅ **Description tone**: no promotional language detected
✅ **Category size**: Financial has 32 items


_Automated diff validation — does not replace maintainer review._
<!-- Sticky Pull Request Commentpr-quality-check -->