docs(testing): document Nix gates and behavioral coverage

Describe canonical local and CI verification, cache reuse, output assertions, workflow boundaries, and observed regression results without treating test counts as coverage targets.

docs/SMOKE.md

@@ -5,8 +5,8 @@ Use `scripts/live-smoke.sh` as the reusable smoke runner for shipped CLI surface
 The script:
 - builds `target/debug/idx` once by default
 - isolates config, cache, and data under `tmp/live-smoke/<timestamp>/`
-- records one log file per case under `tmp/live-smoke/<timestamp>/logs/`
-- supports fast mock-backed runs and slower live-network passes
+- records separate `.stdout` and `.stderr` files per case under `tmp/live-smoke/<timestamp>/logs/`, plus `.validation` diagnostics for JSON checks
+- supports fast mock-backed runs and slower live-network passes; `jq` is required and provided by `nix develop`
 
 ## Common Runs
 
@@ -24,17 +24,44 @@ scripts/audit-msn-fundamentals.sh --tickers BUMI,ADRO,AIMS
 
 ## Nix CI Checks
 
-`nix flake check -L` runs formatting, Clippy, Rust tests, crate packaging, the
-application and ownership-publisher builds, and the offline mock smoke. Crane
-shares dependency build artifacts between the Rust derivations. CI restores the
-Nix store from the GitHub Actions cache, keyed on the flake and Cargo inputs.
+`nix flake check -L` is the canonical local, pre-push, and Linux CI gate. Its
+eleven checks cover:
 
-The publisher regression script remains a separate CI step:
+- Rust formatting, Clippy (`--all-targets`), and all unit/CLI tests
+- the optimized application build and verified crate packaging
+- the packaged ownership publisher's `--help` entry point
+- the offline mock CLI smoke matrix
+- publisher regression scenarios, including the SQLite artifact builder
+- installer regressions under `sh` and `dash`, plus installer and smoke-runner ShellCheck
+
+All check tools are pinned by `flake.lock`. Installer fixtures use resolved
+shell paths, and generated publisher stubs use the running Bash interpreter,
+so the regression suites also work inside the Nix sandbox.
+
+Crane shares dev-profile dependency artifacts between tests, Clippy, and
+`cargo package` verification; the shipped application uses a separate release
+dependency cache. Package verification still builds the packaged crate.
+Integration-test edits do not invalidate the application build, and script
+checks consume only their relevant source files. README/license edits affect
+the packaging check, not the Rust test/application derivations.
+
+CI cache keys include platform, dependency/toolchain inputs, and checked source
+contents. Source changes can therefore save new outputs; restore prefixes first
+reuse the same dependency/toolchain cache, then another cache for the platform.
+The GitHub cache is opportunistic and subject to eviction, not a shared public
+binary cache. Obsolete PR runs are cancelled; main-branch runs are not.
+
+Use individual checks when investigating a failure (replace the system as
+needed), or targeted Cargo commands inside the pinned development shell:
 
 ```bash
-scripts/publish-ownership-snapshot-test.sh
+nix build .#checks.x86_64-linux.publisher-test -L
+nix develop --command cargo test full_screener
 ```
 
+The native macOS installer job remains separate to exercise BSD/macOS tools.
+Live-network smoke is deliberately outside the sandboxed offline gate.
+
 For a live full-list screener check, use an isolated config/cache and run:
 
 ```bash
@@ -48,6 +75,37 @@ candidates. The two offline results must match prefixes of the same cached full
 list. Provider counts and prices vary; live HTTP failures are not offline-test
 failures.
 
+## Coverage Boundaries
+
+The mock preset has 43 cases: 7 general, 19 stock, 9 cache, 2 routing, 4 error,
+and 2 empty/unsupported ownership checks. This is a packaged-binary safety net,
+not a claim that every important behavior is covered by shell smoke.
+
+- All fifteen stock commands run in JSON mode with structural and fixture-value
+  assertions. Four representative table renders check displayed data.
+- JSON checks require exactly one document in the correct stream. Failed
+  commands must leave stdout empty and expose the expected stable error code.
+- Cache scenarios use zero TTL, force provider failures, and compare parsed
+  offline/stale results with the warmed data; diagnostics must stay on stderr.
+- Redundant table launches, duplicate routing cases, and repeated setup checks
+  are omitted rather than counted as extra correctness coverage.
+
+The CLI integration suite carries deeper workflows under the same Nix gate:
+cache misses, provider isolation, filtered reports, non-finite values,
+XLSX/ZIP import and ownership queries, snapshot install/no-op/force, and rejected
+updates preserving database bytes and query results.
+
+Screener regressions generate 503 distinct candidates, with ranking leaders
+beyond the first 500. They exercise top/worst performers, volume, and market-cap
+ordering, a small first request followed by complete offline reads, and rejected
+missing/incomplete totals without cache poisoning. The raw fixture override
+`IDX_MOCK_MSN_SCREENER_FIXTURE` is honored only with `IDX_USE_MOCK_PROVIDER`;
+responses honor the requested batch size so the complete-fetch path is exercised.
+
+Mocks do not verify current upstream availability, authentication, or response
+drift. Live provider checks remain a separate, opt-in operation.
+
+
 
 ## Modes
 
@@ -60,8 +118,8 @@ failures.
 - `general`: `version`, `completions`, `config`, and `cache` command basics
 - `live-table`: all shipped `stocks` commands in live table mode
 - `live-json`: all shipped `stocks` commands in live JSON mode
-- `mock`: all shipped `stocks` commands against the mock provider in both table and JSON mode
-- `cache`: cache warm, `--offline`, and stale-cache fallback checks for quote, technical, and MSN `profile`
+- `mock`: all shipped `stocks` commands against the mock provider in JSON mode, plus representative quote/history/fundamental/financials table renders
+- `cache`: exact data equality across warm, `--offline`, and stale-cache fallback reads for quote, technical, and MSN `profile`
 - `routing`: Yahoo/MSN provider routing plus explicit MSN history behavior
 - `errors`: JSON error contract and invalid flag/input checks
 - `live-nonfinite`: opt-in live MSN fundamentals checks for known non-finite ticker payloads (`BUMI`, `ADRO`, `AIMS`)
@@ -78,4 +136,4 @@ failures.
 - `ownership sync` is still primarily covered by fixture-backed CLI tests rather than the reusable smoke runner.
 - The new `ownership-import` group is intentionally opt-in for explicit `--group ownership-import` runs or `--mode full`; it discovers live URLs first, imports the supported `above1` attachment into the temp DB, then asserts the current `above5` and `investor-type` URLs fail with explicit unsupported-schema UX.
 - The new `live-nonfinite` group is intentionally opt-in only. As of `2026-04-13`, the known real repro tickers are `BUMI`, `ADRO`, and `AIMS`.
-- When a case fails, inspect the per-case log in `tmp/live-smoke/.../logs/` before updating `TODO.md` or `FEATURE_SPEC.md`.
+- When a case fails, inspect its `.stdout`, `.stderr`, and (for JSON cases) `.validation` files in `tmp/live-smoke/.../logs/` before updating `TODO.md` or `FEATURE_SPEC.md`.