Document invocation reporting contracts

docs/cli.md

@@ -66,6 +66,93 @@ version: dev
 revision: ""
 ```
 
+## Reporting
+
+CommandKit applies one shared reporting policy to application handlers,
+integrations, help, version, and CommandKit's own invocation diagnostics. The
+caller passes result and diagnostic writers to `App.Execute`; substantive
+results go to `Streams.Out`, and categorized messages, terminal explanations,
+and usage guidance go to `Streams.Err`.
+
+### Modes and visibility
+
+Each invocation starts in ordinary mode. `--quiet`, `--verbose`, and `--debug`
+are mutually exclusive; the last enabled occurrence selects the mode. They
+accept presence or an explicit boolean value. A `false` occurrence clears the
+selected mode only when it names the current mode, returning to ordinary mode;
+it does not restore an earlier selection. Invalid boolean values are usage
+errors, even if a later flag would select another mode.
+
+| Category | `--quiet` | No mode flag | `--verbose` | `--debug` |
+| --- | --- | --- | --- | --- |
+| Substantive result | Suppressed | Shown | Shown | Shown |
+| Terminal failure | Shown | Shown | Shown | Shown |
+| Warning | Suppressed | Suppressed | Shown | Shown |
+| Info | Suppressed | Suppressed | Shown | Shown |
+| Debug | Suppressed | Suppressed | Suppressed | Shown |
+| Progress, unless enabled explicitly | Suppressed | Suppressed | Suppressed | Shown |
+
+`--progress` independently enables Progress; `--progress=false` disables it.
+Both accept the existing boolean syntax, and the last occurrence wins. An
+explicit setting overrides the mode default, except quiet always suppresses
+Progress. Without an explicit setting, debug enables Progress; ordinary and
+verbose modes leave it disabled. Progress does not enable Info, Warning, or
+Debug.
+
+### Placement and aliases
+
+Reporting flags are available on application commands, the root, canonical
+groups, help, version, and alias-only discovery help. Place them after the
+complete command path; they may be interspersed with operands after that path.
+For example:
+
+```text
+example export --quiet
+example config show --verbose
+example promptkit test all --debug --progress=false
+example help config show --quiet
+example version --quiet
+```
+
+Reporting flags do not go before or between command-path components. Tokens
+consumed as values and tokens after `--` retain their normal meaning.
+
+The reserved long spellings are `--quiet`, `--verbose`, `--debug`, and
+`--progress`; application declarations cannot reuse them. There are no built-in
+short spellings. Applications may define aliases such as `-q → --quiet`,
+`-v → --verbose`, and `-d → --debug`; canonical and aliased occurrences share
+the same ordering. Thus `example export --verbose -q` selects quiet mode.
+
+### Channels and messages
+
+Substantive reports use the result destination. Warnings, Info, Progress,
+Debug, terminal explanations, and usage guidance use the diagnostic destination.
+Simple Warning, Debug, and terminal failure messages begin with `WARN:`,
+`DEBUG:`, and `ERROR:` respectively. Info, Progress, and substantive results
+have no prefix. For multiline messages, the prefix appears on the opening line;
+native structured details keep their own formatting without duplicate labels.
+Progress is streamed as unprefixed lines; terminal redraw and progress bars are
+not provided. A failed outcome with no message or detail uses the fallback
+`ERROR: Command failed.`.
+
+Quiet mode suppresses successful help and version output, as it does other
+substantive results. Usage guidance and routing, parsing, and operational
+failures remain visible in every mode. A recovered problem is reported only if
+the application chooses to submit a Warning; an error cause by itself does not
+create a message.
+
+### Presentation failures
+
+CommandKit continues rendering substantive output under quiet mode through a
+discard destination. This suppresses writes to the caller's result writer while
+still detecting report preparation, encoding, or rendering failures. An
+intentional suppression is not a delivery failure. A failure while rendering or
+writing requested content is retained in the returned `Outcome` and makes an
+otherwise successful or usage invocation operational with status `1`. A domain
+classification and its nonzero status are preserved; a zero-status domain
+outcome becomes status `1` when presentation fails. Earlier bytes already
+written remain visible.
+
 ## Registered command syntax
 
 Options are parsed after the complete command path and may be interspersed with
@@ -223,8 +310,8 @@ interrupt the native value. Existing native markers and leading comments are
 retained; documents without a marker receive one. Scope labels containing line
 control characters are quoted to keep them on one comment line. A provider
 failure leaves the output stream empty. A rendering or output failure may leave
-an aggregate prefix, and the outcome reports
-incomplete report delivery.
+an aggregate prefix; `Outcome.Presentation.Output` records incomplete delivery
+and the destination or rendering error.
 
 ### List configuration sources
 
@@ -390,8 +477,9 @@ again.
 The complete report is prepared before writing. Report preparation failures and
 cancellation observed before report delivery starts leave CommandKit's report
 output empty. Once writing starts, CommandKit does not interrupt the supplied
-writer or roll back delivered bytes. A write error or short write uses the
-existing incomplete-report delivery outcome and can leave partial output.
+writer or roll back delivered bytes. A write error or short write is recorded
+as incomplete delivery in `Outcome.Presentation.Output` and can leave partial
+output.
 
 ## PromptKit definition inspection
 
@@ -607,8 +695,9 @@ execution. See PromptKit's
 Builder, engine-loading, and native validation errors use the operational path
 (status `1`) with supported error identity and acquired diagnostics retained.
 Malformed syntax, missing operands, and unsupported formats use usage status
-`2`. Successful diagnostics and report-delivery failures follow the common
-delivery contract.
+`2`. Successful diagnostics use the common reporting policy. Report delivery
+failures are recorded in `Outcome.Presentation.Output`, separately from the
+operation cause.
 
 ### PromptKit catalogs
 
@@ -802,8 +891,8 @@ outcome. Operation errors use operational status `1`; aggregate runs continue
 after individual errors, retain their reports and ordered error text, and join
 causes for supported `errors.Is`/`errors.As` access. Cancellation stops later
 operations and preserves results already acquired. Report encoding or delivery
-failures use the common incomplete-report delivery outcome and retain operation
-causes where applicable. Syntax, operand, unsupported format, and conflicting
+failures are recorded in `Outcome.Presentation.Output`, separately from
+operation causes. Syntax, operand, unsupported format, and conflicting
 namespace selection are usage status `2`.
 
 Native configuration, selection, and diagnostic meanings remain owned by
@@ -816,4 +905,9 @@ and [engine API](https://gitea.maximumdirect.net/eric/promptkit/src/commit/9178f
 CommandKit usage failures use status `2`; operational failures use status `1`.
 Successful operations use status `0`. Application handlers may return a domain
 classification and status of their choice, which `Execute` preserves. The caller
-chooses how to map an outcome to process exit.
+chooses how to map an outcome to process exit. A rendering or delivery failure
+changes a successful or usage outcome to operational status `1`. A domain
+outcome keeps its classification and nonzero status; a zero-status domain
+outcome becomes `1` if presentation fails. The returned `Outcome.Presentation`
+records output and diagnostic delivery observations separately from its
+operation `Cause`.