feat: library / embedded mode

[mnafees]

Description

Fixes # (issue)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• Documentation change (pure documentation change)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactor (non-breaking changes to code which doesn't change any behaviour)
• CI (any automation pipeline changes)
• Chore (changes which are not directly related to any business logic)
• Test changes (add, refactor, improve or change a test)
• This change requires a documentation update

What's Changed

• Add a list of tasks or features here...

Checklist

Changes have been:

• Tested (unit, integration, or manually with steps specified)
• Linted and formatted
• Documented (where applicable)
• Added to CHANGELOG (where applicable) -- see Keep a Changelog

---

🤖 AI Disclosure

• I acknowledge that an LLM was used in the creation of this Pull Request, in accordance with Hatchet's AI_POLICY.md.

• Details: [e.g. generating tests, writing docs]

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Project	Deployment	Actions	Updated (UTC)
hatchet-docs	Ready	Preview, Comment	Jul 12, 2026 9:53pm

[github-actions]

⚠️ Optional test failure: The old-engine-new-sdk (Python) job failed on this PR. This check is non-mandatory and does not block merging, but may be worth investigating. View logs

[github-actions]

⚠️ Optional test failure: The load-deadlock job failed on this PR (optimistic-scheduling=false). This check is non-mandatory and does not block merging, but may be worth investigating. View logs

[github-actions]

⚠️ Optional test failure: The load-deadlock job failed on this PR (optimistic-scheduling=true). This check is non-mandatory and does not block merging, but may be worth investigating. View logs

[github-actions]

⚠️ Optional test failure: The load-deadlock job failed on this PR (optimistic-scheduling=false). This check is non-mandatory and does not block merging, but may be worth investigating. View logs

[github-actions]

Benchmark results

goos: linux
goarch: amd64
pkg: github.com/hatchet-dev/hatchet/pkg/scheduling/v1
cpu: AMD Ryzen 9 7950X3D 16-Core Processor          
                                         │ /tmp/old.txt │            /tmp/new.txt             │
                                         │    sec/op    │    sec/op     vs base               │
RateLimiter-8                              54.85µ ± 37%   61.72µ ± 41%        ~ (p=0.310 n=6)
Scheduler_Replenish_DenseSharedActions-8                  13.28m ±  6%
geomean                                    54.85µ         905.4µ        +12.52%

                                         │ /tmp/old.txt │            /tmp/new.txt            │
                                         │     B/op     │     B/op      vs base              │
RateLimiter-8                              137.7Ki ± 0%   137.7Ki ± 0%       ~ (p=0.366 n=6)
Scheduler_Replenish_DenseSharedActions-8                  11.69Mi ± 0%
geomean                                    137.7Ki        1.254Mi       +0.00%

                                         │ /tmp/old.txt │            /tmp/new.txt             │
                                         │  allocs/op   │  allocs/op   vs base                │
RateLimiter-8                               1.022k ± 0%   1.022k ± 0%       ~ (p=1.000 n=6) ¹
Scheduler_Replenish_DenseSharedActions-8                  17.46k ± 0%
geomean                                     1.022k        4.224k       +0.00%
¹ all samples are equal

_{Compared against main (0634ede)}

[github-actions]

⚠️ Optional test failure: The load-deadlock job failed on this PR (optimistic-scheduling=false). This check is non-mandatory and does not block merging, but may be worth investigating. View logs