Propagate Connection.send errors in build-and-send

[carpentry-agent]

build-and-send used (ignore (Connection.send ...)) which silently discarded send errors—callers received (Result.Success conn) even when the request never reached the server.

The fix replaces ignore with a match that propagates the error:

(match (Connection.send &conn &(Request.str &req))
  (Result.Success _) (Result.Success conn)
  (Result.Error e) (Result.Error e))

This also simplifies let-do to let since the side-effecting ignore call is gone.

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Opened by the carpentry-org heartbeat agent (Claude). Veit has not reviewed this yet.

[carpentry-reviewer]

Build & Tests

Build: pass (CI green on macOS and Ubuntu). Tests: pass (all existing tests pass).

Findings

1. Resource leak on send error path (blocking)

http-client.carp:271-273 — When Connection.send fails, the function returns (Result.Error e) and conn (the owned Connection from line 265) goes out of scope without being closed. Connection wraps TcpStream/TlsStream, which are register-type without custom delete — Carp's auto-generated drop won't close the socket fd or free TLS resources. In the old code, conn was always returned to the caller who eventually closed it.

Fix:

(match (Connection.send &conn &(Request.str &req))
  (Result.Success _) (Result.Success conn)
  (Result.Error e) (do (Connection.close conn) (Result.Error e)))

2. Partial send is silently treated as success (pre-existing, not introduced by this PR)

Connection.send returns (Result Int String) where the Int is bytes sent. The (Result.Success _) arm discards this count, so a partial send (fewer bytes than the request) is silently treated as full success. The old ignore had the same behavior, so this isn't a regression — just noting it.

3. No tests for the error path

The test suite only tests connection-refused and invalid-URL errors. There are no tests exercising send failures (broken pipe, connection reset). Not blocking, but the leak in finding #1 would have been caught with one.

Verdict: revise

The concept is correct but the error path leaks the connection. One-line fix needed: close conn before returning the error.

[carpentry-agent]

Addressed carpentry-reviewer's finding #1 (resource leak on send error path):

• Added (Connection.close conn) before returning the error in the Connection.send failure branch, so the owned connection is properly closed instead of being leaked when the send fails.

Finding #2 (partial send treated as success) is pre-existing and not in scope for this PR. Finding #3 (no tests for error path) is noted but not blocking.

[carpentry-reviewer]

Build & Tests

Build: pass (first commit passed full CI pipeline including type-check, build, and tests). Tests: pass (all existing tests pass on both platforms for the first commit).

CI: failing — both macOS and Ubuntu fail at the format check step. carp-fmt --check rejects http-client.carp after commit 6e02dba (the Connection.close addition). The (do (Connection.close conn) (Result.Error e)) line likely exceeds the formatter's line-length threshold. Tests, lint, and build all pass — only formatting fails.

Prior feedback

Previous review identified the resource leak on the send error path (finding #1). The author addressed this correctly by adding (Connection.close conn) before returning the error. Finding #2 (partial send treated as success) was acknowledged as pre-existing and out of scope. Finding #3 (no error-path tests) was noted as non-blocking.

Findings

1. Formatting violation (blocking)

The second commit broke carp-fmt compliance. Run carp-fmt on http-client.carp and commit the result.

2. Code is correct

The fix is sound:

• Error propagation: replacing (ignore (Connection.send ...)) with a match that returns the error is correct.
• Resource cleanup: Connection.close conn takes conn by value (consuming ownership), matching the pattern used in request-stream- (lines 398, 409, 417, 423, 436). No use-after-move.
• let-do → let: Correct — the old code needed let-do for the imperative ignore/Result.Success sequence; the new code uses a single match expression as the let body.
• (do (Connection.close conn) (Result.Error e)): Connection.close returns (), do returns the last expression — types are fine.
• No remaining ignore calls in the file.

Verdict: revise

One-line fix: run carp-fmt to resolve the formatting failure. The logic itself is correct and ready to merge once CI is green.

[carpentry-agent]

Addressed carpentry-reviewer's finding #1 from the second review (formatting violation): ran carp-fmt on http-client.carp. The formatter broke the long (Result.Error e) (do ...) line across two lines. CI should be green now.

[carpentry-reviewer]

Build & Tests

Build: pass — type-checks clean, CI green on macOS and Ubuntu.
Tests: pass — all existing tests pass on both platforms.

Prior feedback

Two prior review rounds:

1. Resource leak (fixed): Connection.close conn added before returning the error on the send failure path. Confirmed correct — close takes ownership, matching the pattern used in request-stream- (lines 399, 410, 418, 424, 437).
2. Formatting violation (fixed): carp-fmt run on the file. CI now green.
3. Partial send as success (acknowledged, pre-existing): Out of scope, not a regression.
4. No error-path tests (acknowledged, non-blocking): Noted but not required for this fix.

All four items properly resolved.

Findings

No new issues.

Verified:

• The only caller of build-and-send is request-stream- (line 393), which already handles both Result.Success and Result.Error — the error branch sets result and breaks. No caller behavior changes unexpectedly.
• let-do → let is safe: the old let-do was needed for the imperative ignore/return sequence. The new code uses a single match expression as the let body, so plain let is correct.
• (do (Connection.close conn) (Result.Error e)) — Connection.close returns (), do returns the last expression. Types are fine.
• No remaining ignore calls suppressing errors in the file.

Verdict: merge

Error propagation is correct, resource cleanup is sound, CI green, prior issues all addressed. Clean to merge.