[Pigbibi]

The default-off cash-flow draft had three disconnected seams: its collector returned a projection where the report expected a raw snapshot, no runtime caller wrote that snapshot, and the current publisher's upload whitelist removed externalFlow. This change connects the existing collector to the original report slot and lets the original publisher project and forward it with the same exact opt-in.

The existing account-bound client, valuation time, USD checks, positions opt-in, identity checks and single publisher are retained. The runtime hook always leaves source completeness False. No order, risk, allocation, dependency/pin, workflow or production configuration change is included. SCHWAB_EXTERNAL_FLOW_EXPORT_ENABLED remains OFF unless exactly true; this PR does not enable it.

Scope and independent review:

• Exactly seven files against main 0407949b1b4ebba75fc751682040722aad2876d0: three backend files and four corresponding tests, +614/-1. All other 255 base paths, including deployment workflows and dependencies, are unchanged.
• Independently accepted source head: 198ea40ba4cf254a924b1296708f4a5072b2e0bb.
• History-preserving PR head: 9c6651717973385d84ffd48f76d29b8e9db47438, with parents original draft 818252e349eaf64a4c44b35ab238e4f30e8796c3 and the accepted source head.
• Both full trees are exactly 264d14612bccdcf14419b210c0cc5d8ec8eedcf1. The three local wiring repairs are independently accepted; no extra final changes are carried from the old draft.

Validation at this exact tree:

• Three targeted regressions reproduced the original failures before the repair.
• 114 focused Python tests, 27 separate in-process Worker/SQLite nonempty and rejection checks, Ruff and diff checks passed. Counts are not combined, and local SQLite is not a production runtime.
• The positive offline path uses fake bound SDK responses → actual collector → actual report hook → exact-pinned QPK local writer → JSON readback → actual publisher/prepare → authenticated synthetic QRS receiver → real local SQLite/history. No test-only raw adapter supplies the successful chain.
• Natural GitHub CI for the exact PR head is checked separately before merge.

Known residual acceptance remains explicit:

• T04 FAIL: exact-pinned QPK bfe55791adcd8867790e15dba6fd35304e4093c0 drops an empty transactions: [] during report serialization. A synthetic complete empty window becomes incomplete after readback. The nonempty 27 checks do not satisfy strict T04. Missing/null stay unknown; nothing fills them as zero. QPK and its pin are not changed here.
• T10 NOT_READY: real vendor pagination/continuation, truncation, historical coverage and completeness policy are not established; no invented paging protocol is implemented.

This PR is not fully qualified for production collection or cash-flow returns. There has been no live broker/account authentication, collection/backfill, real archive verification, deployment, image build, flag change or real-money operation for this work. Source permissions, currency/time semantics, full history and production arrival remain unverified. The public-writer fix and any adopter pin update require a separate batch; this engineering integration does not enable them.