Duplicating an underlying error in both the wrapper message and its source

Timing: Follow-up after trial/3 merges into main; defer implementation until then.

Review baseline: Local trial/3 at a094418baf6388e3eeca23821df481a7f0a8751c. This branch is not yet on the remote. Source locations below refer to that snapshot and should be rechecked after merge.

Problem

Error::from_source copies the underlying error's display text into the wrapper message and also retains the same error as its source. Source-chain formatting then repeats the same explanation rather than adding context.

Evidence

crates/lib/src/error.rs:224-229: message is derived from cause.to_string() and the cause is retained.
crates/idea/idea-transformer/src/lib.rs:77-83: parser-error conversion uses the same pattern.
tools/cli/src/diagnostics.rs:47-58: developer formatting prints the wrapper and every cause.
A controlled probe confirmed wrapper Display and source Display both equal disk unavailable, producing a diagnostic such as disk unavailable; caused by: disk unavailable.

Acceptance criteria

Establish a consistent error-wrapping policy: outer errors add distinct context, while source traversal carries the underlying explanation without redundant repetition.
Preserve concrete causes/downcasting, origin metadata, logical invocation frames, and public/private disclosure boundaries.
Review relevant wrappers and verbose formatters together; do not remove causes merely to hide duplicated text.
Verify representative IO/parser and multi-layer diagnostics.

Code examples and suggested direction

At a wrapping boundary, add distinct context while retaining the concrete cause:

use stackpress_lib::{Error, ErrorKind};

let cause = std::io::Error::other("disk unavailable");
let error = Error::new("bootstrap configuration could not be read")
    .with_kind(ErrorKind::External)
    .with_cause(cause);

Expected developer chain:

bootstrap configuration could not be read; caused by: disk unavailable

This illustrates contextual wrapping. The generic from_source conversion still needs an explicit compatibility policy; changing its existing Display text can affect callers and tests.

Suggested investigation and fix notes

Deferred until trial/3 is merged into main. Recheck the merged source and tests first. The snippets are examples/proposals, not an approved patch or a change to frozen contracts.

Inventory Error::from_source, From<serde_json::Error>, From<io::Error>, transformer/parser conversions, and the CLI's bounded source-chain formatter.
Decide the distinction between a contextual wrapper and a transparent/pass-through conversion. Contextual wrappers should explain the failed operation; the source retains the original explanation. Document compatibility implications before changing generic Display/message behavior.
Fix construction/formatting policy rather than deduplicating arbitrary equal strings in the reporter: two different errors can legitimately share text.
Preserve sources/downcasting, source locations, invocation frames, and public disclosure policy. Never remove the source merely to shorten output.
Cover a single IO error, parser coordinates, multiple distinct context layers, and equal-text but distinct failures. Preserve the CLI's finite traversal of cyclic/deep application-defined chains.

Example check for the contextual form:

use std::error::Error as _;

assert_eq!(error.to_string(), "bootstrap configuration could not be read");
let cause = error.source().unwrap();
assert!(cause.downcast_ref::<std::io::Error>().is_some());
assert_eq!(cause.to_string(), "disk unavailable");

Start with Lib request/response diagnostic tests, transformer composition errors, and CLI entry contracts. Reference: standard Error source guidance.

Implementation workflow: After the merge, follow .agents/workflows/rust-programming.md: prove the affected behavior, complete the three test-verified review rounds, and record relevant formatting/lints/docs, feature/platform scope, and applicable development coverage. Preserve unrelated changes.

Fixed on trial/3 in 644795f (merged as 64a5b70, task 00010 lane 1; not yet on main, so leaving open).

Wrappers now add distinct context and keep the concrete cause in source(); the cause's text is no longer copied into the wrapper.
Approved Display change: generic Error::from_source now shows external operation failed; concrete conversions show JSON operation failed / I/O operation failed / integer parsing failed. Known operations use Error::new(context).with_kind(..).with_cause(cause). Documented in Rustdoc and crates/lib/docs/api/error.md.
Downcasting, origins, invocation frames and public disclosure are preserved; developer formatters print each layer once.
Regression error_contracts failed first (wrapper Display was disk unavailable; a three-layer chain repeated its text), now passes.
Server/CLI/transformer callers adopt the same policy in lane 2's follow-up.

Coordinator-verified: fmt, Clippy -D warnings, Rustdoc -D warnings, cargo +1.96.0 check, 454 workspace tests, 856 doctests pass; lib production coverage 93.64%.

Fix owner review issues #11, #1, #2, #5 and lib parts of #4, #7 (task…

Fix owner review issues #10, #3, #8, #9, #13, #12 and host parts of #4,

Apply the #11 error-wrapping policy across server, CLI and transforme…

Finish owner review issues #4, #6, #7 for SQL and framework; neutral …

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Duplicating an underlying error in both the wrapper message and its source #11

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Duplicating an underlying error in both the wrapper message and its source #11

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cblanquera commented on Oct 26, 2026

Suggested investigation and fix notes

cblanquera commented on Oct 26, 2026

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