8.7 KiB
Output policy and invocation reporting
Status: initial planning. The three output modes and uniform treatment of help and version are selected. Consumer API, flag details, and delivery mechanics remain open. Implementation has not started.
Purpose
Provide consistent handling of --quiet and --verbose across application
commands and optional integrations. Reduce repeated output classification,
diagnostic presentation, and delivery bookkeeping where CommandKit can provide
a meaningful benefit.
Ordinary Go writers and formatting functions already make application output straightforward. Design reporting conveniences around the shared output policy and invocation lifecycle. Applications continue to own their report content, domain behavior, and operation outcomes.
Current baseline
Streams and Invocation expose caller-selected output
and diagnostic writers. Outcome and Diagnostic carry
operation causes, diagnostic writers, and delivery state. Handlers can return
Failure(err) or attach diagnostics to an outcome for presentation after the
handler returns. MessageDiagnostic currently writes the supplied message with
a newline; severity does not add a label automatically.
CommandKit coordinates final diagnostic delivery and retains delivery failures separately from the operation cause. Custom handlers can also write directly to the supplied streams and retain responsibility for their output. The existing outcome and channel ownership decisions are recorded in ADR 0005.
Integration adapters already translate upstream diagnostic records into CommandKit diagnostics while preserving native rendering and source context. Some adapters wrap multiple records in one diagnostic writer and classify the batch by its highest severity. This matters when designing selective visibility.
There is currently no shared quiet/verbose policy or invocation reporter API.
Selected output policy
The operator chooses among quiet, ordinary, and verbose presentation:
| Output category | --quiet |
No flag | --verbose |
|---|---|---|---|
| Substantive application output | Suppressed | Shown | Shown |
| Warnings and informational messages | Suppressed | Suppressed | Shown |
| Error diagnostics for a failed run | Shown | Shown | Shown |
Substantive output includes requested reports and command results. Progress and completion chatter are informational messages. The category of a message determines its visibility; stream destination alone cannot distinguish a warning from an error.
Apply the same policy to help and version. There are no command-specific exceptions for successful output:
app help --quiet # succeeds silently
app version --quiet # succeeds silently
Usage and operational failures still report their errors in quiet mode. The feature must distinguish successful output suppression from failure diagnostic delivery.
Tentative direction
Flag and invocation behavior
Model quiet, ordinary, and verbose as mutually exclusive presentation modes. The proposed rule when both flags occur is last occurrence wins, consistent with existing repetition conventions. Exact boolean forms, resets, short spellings, placement, and collision handling remain to be specified.
Keep verbosity a presentation choice: a quiet invocation still performs its requested operation and returns the ordinary outcome. Apply the policy through CommandKit-managed reporting and streams. Output written directly to process streams or external destinations remains application-owned.
Streaming and failure diagnostics
The proposed approach applies visibility when output is emitted. A verbose run may show progress before subsequently failing, and an ordinary run may write part of its substantive output before failing. Previously written bytes cannot be withdrawn. Whole-run buffering solely to make failed runs contain only error output is not part of the proposed direction.
Keep errors understandable in every mode, including source locations and related explanatory context. Unrelated warnings and informational messages remain subject to the selected mode. Retain suppressed diagnostics for programmatic inspection rather than equating suppression with loss of evidence. The exact representation of retained and delivered diagnostics remains open.
Consumer reporting API
An invocation-scoped facility could classify messages, coordinate immediate and
end-of-handler presentation, and retain delivery failures. Earlier illustrative
API shapes included inv.Reporter(), Info, Warn, Diagnostic, and an
AtEnd() view. These names and shapes are exploratory, not selected contracts.
Reassess the necessary API around the output modes before adopting them.
Continue to support standard io.Writer usage for report bodies and native
report writers. Reuse existing diagnostic and outcome concepts where practical.
Any reporting facility should coordinate with returned Outcome.Diagnostics
and operation causes so already-presented messages are not repeated.
Whether reporting methods return write errors, retain them for finalization, or expose an explicit delivery-error accessor remains open. Emitting an error-severity message and deciding the operation's outcome need clearly defined responsibilities.
Upstream diagnostic ownership
ConfigKit and PromptKit remain authoritative for their diagnostic semantics, severity, source context, and disclosure rules. Integration adapters expose those capabilities through the shared CommandKit presentation policy.
Support consistent reporting of ConfigKit errors and warnings as its adopted public API evolves. This roadmap does not assume that a future warning API already exists or prescribe its upstream shape. Preserve useful native diagnostic detail and supported error identity, and coordinate returned errors with diagnostics that already explain them.
Work needed
- Settle the open decisions with examples covering ordinary application output, immediate and deferred diagnostics, failure after partial output, help and version, and integration diagnostics in every mode.
- Review current diagnostic batching, parsing, help, outcome presentation, and
writer ownership to identify the smallest shared changes. Include invocation
failures that occur before a handler receives its
Invocation. - Specify the public API and flag contracts, including interactions with command and flag aliases. Assess existing flag collisions and compatibility impact.
- Implement the selected behavior across core and the integrations. Preserve upstream rendering and semantics while applying the chosen visibility policy.
- Verify classification, flag selection, suppression, retained diagnostics, ordering, duplicate prevention, and write-failure handling with focused behavioral tests and maintained consumer examples.
- Update GoDoc, the CLI reference, consumer guidance, and release documentation when implemented. Review whether any resulting architectural change needs an ADR; exact reporting APIs and flag syntax remain API/CLI contracts.
Open Decisions
OD-1: Flag grammar and scope
How are quiet and verbose selected, repeated, combined, or explicitly reset? Are short spellings built in? Where may the flags appear, including on help requests? How are canonical and alias spelling collisions handled, and how is the mode determined for invocations that fail during routing or parsing?
OD-2: Consumer API and output classification
What is the smallest API for substantive output, informational messages,
warnings, and errors? How do direct writes through Invocation.Streams interact
with it? How can helpers report through the same invocation? Is a dedicated
immediate/deferred reporter needed, and how does it compose with existing
outcome diagnostics?
OD-3: Failure presentation and diagnostic retention
What identifies an error that must be shown, particularly for application domain outcomes and error-severity diagnostics accompanying a successful outcome? Which contextual records belong to an error explanation? How are mixed upstream diagnostic batches filtered while preserving useful native rendering? What is retained when presentation is suppressed, and how is duplicate presentation prevented without hiding unrelated failures?
OD-4: Delivery lifecycle and quiet execution
How are immediate and deferred messages ordered and finalized, including when the operation fails? How do callers observe and react to write failures? What delivery state represents intentional suppression? Does quiet mode discard rendered bytes or skip report rendering, and how does that choice preserve operation semantics and failure detection? Which streaming behavior becomes part of the public contract?