[Tracking] WinterTC (TC55) Minimum Common Web API: gap analysis for boa_runtime #4988

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1. KaustubhOG commented on Mar 10, 2026

   

   KaustubhOG

   on Mar 10, 2026

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   Hey @hansl following up on our Matrix conversation. I went through thel TC55 spec manually and cross-referenced it against the boa_runtime source to put together the gap analysis above.

   Based on the direction you outlined, here's my understanding of the full plan:

   • Create a new boa_tc55 crate containing only TC55-mandated APIs
   • Migrate existing TC55-compliant APIs from boa_runtime → boa_tc55
   • Implement the missing TC55 APIs in boa_tc55
   • boa_runtime re-exports boa_tc55 and keeps non-TC55 extras (like fs)
   • Future: move boa_tc55 to its own repo under boa-dev at Boa 1.0

   A few things I noticed while auditing the source:

   • URL.searchParams / createObjectURL / revokeObjectURL are currently stubbed and throw "not implemented"
   • Event/EventTarget should likely come first since AbortController, MessageChannel, and the entire Streams API alll depend on it
   • WebAssembly.* probably wants a separate discussion (maybe i deducted because it looks more complex for now )

   Note: I verified everything manually against the source, but if anything in the gap list looks off — either already implemented or something miscategorized will be update the issue anytime.

   Looking forward to your thoughts on the plan and next steps
3. KaustubhOG commented on Mar 11, 2026

   

   KaustubhOG

   on Mar 11, 2026

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   Hey @Tanush576, thanks for the interest in helping with this!

   Right now I'm working on the initial architectural setup for this effort (specifically around introducing the boa_tc55 crate and defining how the APIs will be structured and registered). Since several of the APIs listed here depend on shared infrastructure and crate structure, I'm first discussing and finalizing that design i am currently working on it .

   I'm also implementing parts of this issue in parallel, so starting individual APIs right now might lead to duplication or mismatches with the planned architecture.

   Once the crate structure and architecture are finalized, I'll break the remaining work into smaller issues

   In the meantime, feel free to contribute to other open issues — there are quite a few good ones in the repo listed .
5. KaustubhOG

   added a commit that references this issue on Mar 15, 2026

   feat: add boa_tc55 crate skeleton for WinterTC TC55 compliance

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   46a3d65
6. jedel1043

   assigned

   KaustubhOG

   on Mar 18, 2026
7. github-merge-queue

   added a commit that references this issue on Mar 18, 2026

   feat: add boa_wintertc crate skeleton for WinterTC compliance (#5105)

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   1d0d8cb
8. KaustubhOG commented on Mar 31, 2026

   

   KaustubhOG

   on Mar 31, 2026

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   Progress Update

   Phase 1 and Phase 2 are complete via #5105 (merged).
   The boa_wintertc crate is now established with all 10 module stubs, and the architecture has been validated.

   ---

   Current Status

   • Phase 1 → boa_wintertc crate created
   • Phase 2 → Architecture finalised
   • Phase 3 → Migration from boa_runtime
   • Phase 4 → New API implementations

   ---

   Phase 3 Plan Migration (No Regressions)

   Migrate modules from boa_runtime into corresponding boa_wintertc stubs as-is:

   console    → boa_wintertc::console
   interval   → boa_wintertc::timers     (renamed)
   microtask  → boa_wintertc::microtask
   clone      → boa_wintertc::clone
   base64     → boa_wintertc::base64
   abort      → boa_wintertc::abort
   fetch      → boa_wintertc::fetch
   text       → boa_wintertc::encoding   (renamed)
   

   Implementation Approach

   Each module will be migrated in order of complexity:

   1. base64, clone, microtask (self-contained, no internal dependencies)
   2. console, timers, abort ( minor wiring adjustments )
   3. encoding (rename from text to align with TC55 naming )
   4. fetch (last, complex, has sub-files (headers.rs, request.rs, response.rs)

   For each module:

   • Copy source files into the corresponding boa_wintertc stub
   • Update internal use paths
   • Add any missing dependencies to boa_wintertc's Cargo.toml
   • Verify all existing tests pass

   ---

   Notes

   • This is a location change the same code moves from boa_runtime to boa_wintertc, no logic changes
   • All existing tests will be preserved and must pass after migration
   • No TC55 compliance fixes during this phase ,compliance gaps are left for Phase 4

   ---

   cc @jedel1043

   • Does the implementation approach looks fine ?
   • Once migration is done, should boa_runtime immediately re-export from boa_wintertc, or should the two crates temporarily coexist until Phase 4 is complete?
9. KaustubhOG commented on Jun 28, 2026

   

   KaustubhOG

   on Jun 28, 2026

   Last edited by KaustubhOG

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   Phase 3 (migration) progress update

   Module (boa_runtime -> boa_wintertc)	APIs	Status
   base64	atob, btoa	Merged (#5418)
   clone	structuredClone (+ store)	In review (#5419)
   microtask	queueMicrotask	In review (#5419)
   interval -> timers	setTimeout, clearTimeout, setInterval, clearInterval	In review (#5419)
   console	console.*	W.I.P
   text -> encoding	TextEncoder, TextDecoder	W.I.P
   abort	AbortController, AbortSignal	W.I.P
   fetch	fetch, Request, Response, Headers	W.I.P
   url (partial)	URL	W.I.P
10. pull

    added a commit that references this issue on Jul 17, 2026

    feat(wintertc): migrate atob/btoa from boa_runtime (boa-dev#5418)

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    6ef5370
11. KaustubhOG

    added 2 commits that reference this issue on Jul 23, 2026

    feat(wintertc): migrate console from boa_runtime

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    422e9c5

    feat(wintertc): migrate console from boa_runtime

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    3f91412
12. pull

    added a commit that references this issue on Jul 25, 2026

    feat(wintertc): migrate console from boa_runtime (boa-dev#5441)

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    b4e6e5a