feat(storage): preserve observation fidelity and analytical handoffs - #125

User workflow

Keep source observations intact from imported CSV/Parquet through local storage and a pandas analytical price panel. This is the market/temporal input batch of the accepted successor migration, not an analytical cleaner or runtime history engine.

Closes #117.

Changes

• Flat/Hive reads retain source timestamp precision, label declarations and timezone-correct half-open bounds. Declared source timezones govern naive observations. Hive prunes in its physical partition clock and orders numeric partition values rather than directory strings.
• Typed empty Hive generations retain schema. Invalid temporal declarations fail before replacing an existing generation. Declared timestamp columns work without renaming physical source data.
• utils.conversion.to_price_panel/from_price_panel retain clock, typed asset IDs, nullable integer scale and explicit missing cells, including native NaN versus null. A presence mask distinguishes an absent pair from a supplied null. Conflicting mappings, duplicates and stale masks fail without caller mutation. No filling, returns calculation or inferred availability.
• Extend the existing migration guide and add a runnable offline CSV-to-disk-to-panel recipe. Other observation fields and availability/revision facts stay in the original tables.

Executed evidence

• Base a9a9084 reproduced real DataManager disk failures: adjacent nanoseconds rounded to microseconds, label bounds and a timezone-shifted Hive partition omitted. Passing repairs retain existing UTC representation where a label timezone is declared.
• Qualified source bfc7f3a passed4264 tests in each full native and separate ResourceWarning lane,292 deselected,86.58% coverage. Final headce48de95b432c9588f249a1d7ba80422277689c7 incorporates security main with an independently verified identical Git tree. Cases include a whole missing price session,signed/unsigned integer scale,custom mappings,CME overnight,NYSE early close,DST and crypto weekends.
• Seven premise/claim controls each pass on correct producing code and fail on a deliberately broken producer. Aggregate gate: seven covered, no waivers, findings, unreachable items or deferrals.
• Fresh final-head wheel and source-distribution installs,isolated Python3.12 with source-path injection disabled: Data0.2.2.dev23+gce48de95b,Specs0.2.0,Diagnostic0.1.9 and Engineer0.1.7.dev29+gc69e7bada from immutable commitc69e7badaac012ad98b1c4b8aa9a67a952b08f5c. All165 packaged source files match Gitce48. Eight produced observations and the missing quote survive. Independent A outcomes.01,-3/101,5/98,null and B.04,null,null,null agree through public consuming APIs.
• Lint,format,type,strictdocs,wheel/sdist,actionlint and all hooks passed. Exactce48 hosted qualification completed26SUCCESS and the sole configured Python3.15 prerelease skip;its required exception validator passed. Both nine-platform supported and nine-platform ecosystem matrices passed. No gate bypass or blind rerun.

Compatibility and scope

The qualified workflow uses immutable Engineer source;published0.1.6 requires Specs<0.2 and cannot resolve with current Data. The guide records the source candidate and resolver boundary instead of claiming released-package compatibility. No consumer is a mandatory Data dependency.

No new release, tag, package publication or documentation deployment. Existing0.2.1 remains immutable. The independently reviewed-green aiohttp security update landed through PR116 as728b84c and is incorporated from current main without mixing its attribution into this implementation.

Security prerequisite PR123 landed9b366707cfad6b3844e92f0638f15e09aa13f611 after all applicable gates passed. Normal guarded main reconciliation producedce48;source/tests/docs remain byte-identical to qualifiedbfc and all new-head checks passed.

AI assistance was used for implementation, regression tests and documentation. The substantive diff, producer failure controls and consumer outputs were reviewed in this owner workflow. Merge remains conditional on all final-revision gates.