2026-08-03 11:52:13 -04:00
1 changed files with 188 additions and 0 deletions
@@ -0,0 +1,188 @@
 # `cog_balances()` — a reader surface for cash and security holdings
 **Issue:** `uscogdata#25` requirement 2 · **Downstream:** `cog-api#26`
 **Date:** 2026-08-03 · **Status:** design, awaiting approval
 Requirement 1 of `uscogdata#25` (no `balance` row may reach a money verb) shipped
 with `#11`/`#12` and is asserted at both view and verb level. This spec covers
 requirement 2 only: a way to query holdings.
 ## Decision: a verb, not an argument
 `cog_balances()`, parallel to `cog_spending()` / `cog_revenue()`.
 Holdings are a **stock** — a balance at a point in time — while the money verbs
 return **flows** over a fiscal year. The flow verbs' whole argument vocabulary
 is meaningless for a stock: `expenditure_concept` / `revenue_concept` describe
 which flows Census aggregates into a published total, and `complete=` fills a
 grid of fiscal-year cells. Overloading a money verb would put a stock behind
 arguments that all assume a flow.
 ## The 14 codes
 Measured against the published corpus 2026-08-03, not transcribed from the
 issue. `year_min`/`year_max` are observed row extents.
 | `balance_subtype` | `category` | codes | observed years |
 |---|---|---|---|
 | `general` | Fund Balances | `W01`, `W31`, `W61` | 2012–2021 |
 | `employee_retirement` | Retirement System Holdings | `X21`, `X42`, `X44` | 1967–2016 |
 | | | `X47` | 1988–2016 |
 | | | `X30`, `Z77`, `Z78` | 2012–2016 |
 | `unemployment_trust` | Insurance Trust Balances | `Y07`, `Y08` | 1967–2023 |
 | `workers_comp_trust` | Insurance Trust Balances | `Y21` | 2012–2023 |
 | `other_insurance_trust` | Insurance Trust Balances | `Y61` | 2012–2023 |
 ## Architecture
 ### Two new views
 Mirroring the `revenue_long` / `revenue_annotated` pair exactly:
 - `inst/sql/26-balance_long.sql` — `category_type = 'balance' AND NOT is_aggregate`
 - `inst/sql/46-balance_annotated.sql` — joins `canonical_fips_xwalk` and
  `summary_categories`, exposing `category`, `category_type`, `balance_subtype`
 `.register_views()` globs `inst/sql/*.sql` in sorted order, so both register
 with no new registration code.
 ### A third gate list in `R/views.R`
 `CREATE VIEW` resolves its source schema eagerly, so a missing **column** fails
 at registration time, not at query time. `46-balance_annotated.sql` selects
 `c.balance_subtype`, which exists only on corpora built after pipeline `#76`/`#77`.
 That arrived without a `schema_version` bump, so neither existing gate applies:
 `.harmonization_view_files` keys on `schema_version`, `.representation_view_files`
 on the presence of a *file*. The discriminator here is a **column on an existing
 table**.
 ```r
 .balance_view_files <- c("26-balance_long.sql", "46-balance_annotated.sql")
 ```
 gated by probing `summary_categories` for `balance_subtype`, with
 `cog_balances()` erroring cleanly via `.require_balance_support()` on an older
 corpus — mirroring how `.require_schema_v5()` gates the harmonized views.
 ### `R/balances.R` — a dedicated path, not `.verb_spendrev()`
 `.verb_spendrev()` is 825 lines whose concept scoping, intergovernmental leg and
 `complete=` grid are all flow-specific, and four verbs depend on it. Threading a
 third mode through it adds branching to shared code for no reuse benefit.
 Reused unchanged: `.build_provenance()`, `.build_series_break_refs()`,
 `.build_corpus_break_refs()`, the population join, `.inflate()`, and
 `.coerce_govid_input()`.
 Following the package's real two-layer convention: **view definitions** live in
 `inst/sql/`; **query construction** is inline `sprintf()` in R, as in
 `.verb_spendrev()`. (`CLAUDE.md` currently states "never inline SQL strings in R
 files", which the verb layer has never obeyed. Corrected in a separate commit —
 see Out of scope.)
 ## Signature
 ```r
 cog_balances(govid, years,
             subtype        = NULL,   # general | employee_retirement |
                                      # unemployment_trust | workers_comp_trust |
                                      # other_insurance_trust
             category       = NULL,   # Fund Balances | Insurance Trust Balances |
                                      # Retirement System Holdings
             per_capita     = FALSE,
             adjust_to_year = NULL,
             basis          = c("harmonized", "raw"))
 ```
 Returns a `tbl_df` with a `provenance` attribute, like every other verb.
 **Absent by design:** `expenditure_concept`, `revenue_concept`, `complete`.
 **`per_capita` is offered.** Holdings per resident is a real measure (pension
 assets per capita, fund balance per resident). The roxygen `@param` states
 plainly that this is a *stock per resident* and is **not** comparable to
 `cog_spending()`'s per-capita figures.
 **`basis` is currently a no-op** — `harmonization_map` has zero balance-code
 rows, so harmonized and raw are identical for holdings. Kept for uniformity
 with the money verbs (the API would otherwise special-case), and
 `provenance$basis_note` says so outright rather than letting it look meaningful.
 **`recipe` is deliberately omitted from v1.** See below.
 ## Decision point: `recipe=` deferred to v2
 The two holdings recipes are unusable from this verb today, and shipping the
 argument anyway would produce a silently truncated series.
 `cash_securities_z77_wide` = `X40` (1967–2011) + `Z77` (2012–2023);
 `cash_securities_z78_wide` = `X41` (1967–2011) + `Z78` (2012–2023).
 **`X40` and `X41` have zero rows in `summary_categories`.** They carry ~42,700
 rows in the corpus across 1967–2011, but with no `category_type` they cannot
 appear in a `category_type = 'balance'` view. Applying either recipe would
 return only the modern leg — 2012–2016 — dropping 45 years while looking like a
 valid continuous series. That is precisely the "plausible rather than obviously
 wrong" failure mode `#25` exists to prevent.
 The fix is upstream, in the pipeline crosswalk. Until it lands, `cog_balances()`
 does not accept `recipe`, and an attempt to pass one is an error naming the
 blocking issue rather than a silent partial result.
 ## Caveat surfacing
 `provenance$balance_caveats`, always present, plus one `cli_inform()` per
 session per caveat class when a query actually touches an affected family or
 year. Structured so `cog-api#26` can forward the fields verbatim.
 Three of the four caveats need reader-side work. **My earlier assumption that the
 catalogued series breaks would cover them is wrong**, verified against
 `series_breaks.parquet`:
 | # | Caveat | Covered by existing machinery? |
 |---|---|---|
 | 1 | Gross holdings, **not GAAP fund balance**; no liabilities netted | No — constant, new field `not_gaap = TRUE` |
 | 2 | `W` is FY2012–2021 only | No — new `coverage_window`, **computed** from the corpus |
 | 3 | `X`/`Z` family ends FY2016 | **No.** SB197–SB202 attach to `X02`/`X05`/`X08`/`X11`/`X12`, which are *flow* codes. The holdings codes have no catalogued break for their FY2016 termination. Surfaced via `coverage_window` |
 | 4 | `X40`/`X41` book → market at FY2002 | **No.** SB195/SB196 attach to `fin_code` `X40`/`X41`, which are outside the balance view (see above). Surfaced as an explicit caveat when the year range crosses 2002 and touches `employee_retirement` |
 `coverage_window` is derived per observed subtype family from the corpus, never
 hardcoded, so it stays correct as the corpus grows.
 `series_break_refs` and `corpus_break_refs` are still populated by the existing
 code-driven builders — they simply contribute nothing for the four caveats
 above, and will start contributing once the upstream gaps close.
 ## Testing
 New `tests/testthat/test-balances.R`. The bundled fixture covers all four
 fixture years — `W` in 2012/2019/2020, the `X`/`Z` family in 2011/2012, `Y`
 throughout — so every test below runs offline.
 - **Inverse guard.** No flow code ever appears in `cog_balances()`, complementing
  the already-asserted forward guard. Absence is verified against the raw corpus
  via `read_parquet` on `data/long`, never through the verb that creates it.
 - **FY2016 seam.** The `X`/`Z` family is present in 2012 and absent in 2019;
  `coverage_window` reports the termination and the console message fires once.
 - **Caveats.** `not_gaap` is always `TRUE`; `coverage_window` matches the
  measured table above; the FY2002 valuation caveat fires only when the year
  range crosses 2002 *and* touches `employee_retirement`.
 - **`per_capita`.** `amt_per_capita_nominal == amt_nominal / population`.
 - **`recipe` rejection.** Passing `recipe` errors with a message naming the
  blocking issue.
 - **Gating.** `.require_balance_support()` errors cleanly on a corpus whose
  `summary_categories` lacks `balance_subtype`.
 ## Out of scope, tracked separately
 1. **Pipeline issue (new).** Add `summary_categories` rows for `X40`/`X41`
   (`category_type = 'balance'`, `balance_subtype = 'employee_retirement'`), and
   catalogue a series break for the FY2016 termination of the holdings codes.
   Unblocks `recipe=` and lets caveats 3 and 4 flow through the existing
   builders. Requires a corpus rebuild + republish, which is a separate,
   human-approved operation.
 2. **`cog-api#26`.** Adds `/balances` in all three required places — handler,
   `param_contract`, and the `plumber.R` route signature. Lands after this.
 3. **`uscogdata/CLAUDE.md` refresh.** Separate commit. It is stale: it claims 7
   SQL views (there are 21), 181 tests (716), a two-year fixture (four years),
   and a "never inline SQL" rule the verb layer does not follow.