Add collaborative markdown document tools

[samwillis]

Summary

Stacked on #4555. Adds collaborative markdown documents for Electric Agents. This PR consumes the streaming tool-call hook from #4555, but keeps the markdown document implementation in a separate layer.

What this adds:

• A document manifest entry for markdown docs with:
  • content MIME: text/markdown
  • transport MIME: application/vnd.electric-agents.markdown-yjs
  • provider: y-durable-streams
  • Y.Text name: markdown
• Horton/worker markdown tools for creating, reading, replacing, editing, and streaming inserts into markdown docs.
• Runtime-side document sessions that materialize a wake-local Y.Doc, keep it synced through @durable-streams/y-durable-streams, and append binary Yjs updates to durable streams.
• Raw Yjs update and awareness stream support on the server; the server creates streams and serves metadata but does not semantically edit document content.
• CodeMirror/Yjs markdown editor UI with open and split-right actions from timeline and manifest surfaces.
• Agent and user presence plumbing based on Yjs awareness, with agent cursor placement during streamed insert/replace operations.
• Worker sharing of markdown document refs so spawned workers can collaborate on the same document.

Architecture notes:

• The agent runtime owns semantic document edits. Tools mutate the local wake-scoped Y.Doc; the Yjs provider writes updates to the durable stream.
• The agents server stays deliberately dumb for document contents: it creates/locates streams, proxies durable stream access, and stores the manifest row.
• Presence follows the same split: clients and agents publish raw Yjs awareness updates; the server does not interpret cursor positions.
• Basic replace/edit tools remain available for non-streaming edits; streamed insert/replace builds on feat(agents): Add streaming tool call argument support #4555's onArgsDelta hook.

Validation

• pnpm --filter @electric-ax/agents-runtime typecheck
• pnpm --filter @electric-ax/agents-server-ui typecheck
• pnpm --filter @electric-ax/agents typecheck
• pnpm --filter @electric-ax/agents-server typecheck
• pnpm --filter @electric-ax/agents-runtime exec vitest run test/markdown-docs-tools.test.ts test/outbound-bridge.test.ts test/pi-adapter.test.ts
• pnpm --filter @electric-ax/agents-runtime exec vitest run test/runtime-dsl.test.ts
• pnpm --filter @electric-ax/agents exec vitest run test/spawn-worker-tool.test.ts test/horton-tool-composition.test.ts test/horton-system-prompt.test.ts
• pnpm --filter @electric-ax/agents-server exec vitest run test/electric-agents-routes.test.ts test/electric-agents-status.test.ts test/electric-agents-manager-write-validation.test.ts
• pnpm --filter @electric-ax/agents-server-ui exec vitest run src/components/views/MarkdownDocumentView.test.ts src/lib/workspace/workspaceReducer.test.ts
• pnpm --filter @electric-examples/yjs run typecheck
• pnpm --filter @electric-ax/agents-mobile run ci:check
• git diff --check

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[codecov]

Codecov Report

❌ Patch coverage is 53.46633% with 933 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.60%. Comparing base (636d716) to head (28be27c).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
packages/agents-runtime/src/tools/markdown-docs.ts	76.32%	224 Missing ⚠️
...r-ui/src/components/views/MarkdownDocumentView.tsx	8.77%	156 Missing ⚠️
packages/agents-runtime/src/markdown-yjs.ts	43.41%	116 Missing ⚠️
...es/agents-runtime/src/markdown-document-session.ts	0.86%	115 Missing ⚠️
...ckages/agents-runtime/src/runtime-server-client.ts	8.19%	112 Missing ⚠️
packages/agents-server/src/markdown-documents.ts	44.15%	43 Missing ⚠️
...agents-server-ui/src/components/EntityTimeline.tsx	0.00%	24 Missing ⚠️
packages/agents-runtime/src/process-wake.ts	8.00%	23 Missing ⚠️
packages/agents-runtime/src/manifest-helpers.ts	12.00%	22 Missing ⚠️
packages/agents-server/src/entity-manager.ts	77.27%	20 Missing ⚠️
... and 8 more

Additional details and impacted files

@@                            Coverage Diff                            @@
##           samwillis/agents-streaming-tool-calls    #4530      +/-   ##
=========================================================================
+ Coverage                                  55.05%   56.60%   +1.55%     
=========================================================================
  Files                                        318      360      +42     
  Lines                                      37016    40834    +3818     
  Branches                                   10547    11241     +694     
=========================================================================
+ Hits                                       20379    23116    +2737     
- Misses                                     16604    17661    +1057     
- Partials                                      33       57      +24     

Flag	Coverage Δ
packages/agents	72.03% <82.45%> (+1.50%)	⬆️
packages/agents-mcp	77.54% <ø> (?)
packages/agents-mobile	84.09% <ø> (+12.66%)	⬆️
packages/agents-runtime	79.23% <58.11%> (-1.18%)	⬇️
packages/agents-server	72.87% <61.92%> (-1.12%)	⬇️
packages/agents-server-ui	6.12% <6.60%> (+0.45%)	⬆️
packages/electric-ax	46.42% <ø> (ø)
packages/experimental	87.73% <ø> (?)
packages/react-hooks	86.48% <ø> (?)
packages/start	82.83% <ø> (?)
packages/typescript-client	91.83% <ø> (?)
packages/y-electric	56.05% <ø> (?)
typescript	56.60% <53.46%> (+1.55%)	⬆️
unit-tests	56.60% <53.46%> (+1.55%)	⬆️

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[github-actions]

Electric Agents Desktop Builds

Build artifacts for commit 28be27c.

Platform	Status	Artifact
macOS Apple Silicon	Passed	DMG
macOS Intel	Passed	DMG
Windows x64	Passed	Installer
Linux x64	Passed	AppImage / deb

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[github-actions]

Electric Agents Mobile Build

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Add the mobile-eas-build label to this PR to produce an installable preview build.

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