fix(wasm): make the streaming micropip install engine actually run

[dmadisetti]

📝 Summary

Follow-up to #9702, with fixes for the bump to micropip 0.11 from 0.9.

Installing 8 packages from that prompt, median of 4 runs on one machine against
the Python Package Index (PyPI):

	click to last package installed
before	2.4 s (range 1.9–3.9)
after	0.5 s (range 0.3–0.8)

Note, times vary with network conditions.
Each run uses a fresh browser profile, so no package comes from a previous run. marimo fetches package metadata prior to installation click, so both rows understate the cost of resolving packages against a cold cache.

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Project	Deployment	Actions	Updated (UTC)
marimo-docs	Ready	Preview	Aug 12, 2026 10:58pm

[github-actions]

All contributors have signed the CLA ✍️ ✅
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[cubic-dev-ai]

All reported issues were addressed across 3 files

Architecture diagram

sequenceDiagram
    participant UI as WASM Notebook UI
    participant Runtime as Marimo Runtime
    participant Engine as Stream Transaction Install Engine
    participant Micropip as Micropip Module (Pyodide)
    participant PkgMgr as Package Manager Singleton
    participant Txn as Transaction
    participant Packaging as Packaging Library
    participant PyPI as PyPI Server

    Note over UI,PyPI: Streaming Micropip Install Flow (micropip >= 0.11)

    UI->>Runtime: Request package installation (batch)
    Runtime->>Engine: stream_transaction_install(packages)
    
    Engine->>Micropip: Import micropip module
    Engine->>Packaging: Import packaging.markers.default_environment
    
    alt Current micropip (>= 0.11)
        Engine->>Micropip: Access _package_manager_singleton
        Micropip-->>Engine: PackageManager instance
    else Legacy micropip (< 0.11)
        Engine->>Micropip: Access _micropip
        Micropip-->>Engine: PackageManager instance
    end

    Engine->>PkgMgr: Get compat layer & defaults
    PkgMgr-->>Engine: index_urls, constraints, compat
    Engine->>Packaging: Get default_environment()
    Packaging-->>Engine: PEP 508 markers
    
    Engine->>Txn: Create Transaction(requirements, ctx, compat)
    Txn-->Txn: Resolve dependencies & fetch metadata
    
    loop Per-package resolution
        Txn->>PyPI: Fetch wheel metadata
        PyPI-->>Txn: Package metadata
        Txn->>Txn: Collect wheels (success) or Requirement objects (failure)
    end
    
    Engine->>Txn: Install collected wheels (parallel)
    Txn->>PyPI: Download wheels
    PyPI-->>Txn: Wheel content
    
    alt All packages resolved
        Engine->>Runtime: Yield (package_name, True) per package
    else Some packages failed
        Txn-->>Engine: failed list contains Requirement objects
        Engine->>Engine: Extract .name attribute from each Requirement
        Engine->>Runtime: Yield (original_pkg_name, False) per failure
    end
    
    Runtime-->>UI: Installation results (success/failure per package)

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<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[Copilot]

Pull request overview

Updates marimo’s WASM/Pyodide micropip streaming installer to match newer micropip internals so the parallel “Transaction”-based install path actually runs (instead of silently falling back to sequential installs), and adds coverage to detect future API drift.

Changes:

• Switches the streaming engine to use micropip’s renamed global package-manager singleton and packaging’s marker environment helper.
• Fixes resolution-failure handling by interpreting Transaction.failed entries as Requirement objects (and adds tests for versioned specs).
• Extends Pyodide acceptance coverage by installing real packages via stream_transaction_install and asserting they import.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
marimo/_runtime/packages/_micropip_streaming.py	Updates private micropip integration points and failure handling for streaming installs.
tests/_runtime/packages/test_micropip_streaming.py	Updates stubs/tests to reflect the new singleton name and Requirement-based failure entries; adds new assertions.
tests/_pyodide/test_pyodide_acceptance.mjs	Adds an acceptance step that exercises the streaming engine against real micropip in Pyodide.

Suppressed comments (1)

tests/_runtime/packages/test_micropip_streaming.py:152

• The test name says it “reports_base_name”, but the behavior/assertion is that a versioned request is yielded back using the caller’s original spec string ("foo==1.2.3"). Renaming the test to match the actual contract will avoid confusion when maintaining failures.

async def test_failed_requirement_with_specifier_reports_base_name(

---

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