Seal the fetch target: one value holds the URL and its host

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

docs/implementer-log.md

@@ -6,6 +6,7 @@ reviewer adds findings under "Reviews" once per milestone.
 
 | Task | Date | Status | Gate runs | First gate | Deviations | Notes | Model |
 |---|---|---|---|---|---|---|---|
+| M3b/02-brokerd-fetch-url | 2026-09-22 | done | 1 | pass | none | Sealed the fetch target: replaced the two-field `ToolArgs::HttpFetch { url, host }` variant with a tuple variant `HttpFetch(FetchUrl)` holding a new `FetchUrl { url, host }` struct whose fields are private and exposed only through `url()`/`host()`; `parse` is the only constructor. Added the two doctests word for word (a `compile_fail` proving the struct cannot be built outside `args`, and a passing one reading the parsed value through getters). Changed the four match sites that built or read the old variant: `tool` (`HttpFetch(_)`), `canonical_json` (`HttpFetch(target)` serialising `HttpFetchArgs { url: target.url.clone() }`, still only the URL), `parse` (`HttpFetch(FetchUrl { url: value.url, host })`), and `policy::covers` (`HttpFetch(target)` matching with `host_matches(pattern, target.host())`); `runner.rs` `HttpFetch { .. }` became `HttpFetch(_)`. Copied the new `tests/args.rs` (one test now reads the parsed value through getters). `grep "FetchUrl {"` shows the struct def, impl opener, the `parse` line and the doctest only; `grep "HttpFetch {"` shows nothing. All brokerd tests and doctests pass; `make gate` prints `gate: ok` on the first run. | ? |
 | M3b/01-proto-tools-hosts | 2026-09-22 | done | 1 | pass | none | Copied `tools.rs` and `hosts.rs` from the plan's `files/` into `crates/proto/tests/`; they fail to compile until the modules exist. Created `crates/proto/src/tools.rs` with the four public arg structs (ReadFile/Write/Shell/HttpFetch), each `#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]` and `#[serde(deny_unknown_fields)]`, `ShellArgs` keeping its `#[serde(default, skip_serializing_if = "Option::is_none")]` cwd; and `crates/proto/src/hosts.rs` with private `valid_label` plus `valid_host`, `valid_host_pattern`, `host_matches`, bodies and doc comments unchanged. Added `pub mod hosts;` and `pub mod tools;` to `proto/src/lib.rs` in alphabetical order (no re-exports). Deleted the private structs from `brokerd/src/args.rs`, added `use proto::tools::{...}` at the top and the `pub use proto::hosts::{...}` re-export where the functions were, and dropped the now-unused `use serde::{Deserialize, Serialize}`; `url_host`, `valid_path`, `inside` and `MAX_URL` stay. New suites 3 and 3 pass; brokerd args/grants/policy pass unchanged. `grep "fn valid_host\|struct ShellArgs"` shows one extra line, `brokerd/tests/args.rs:91`, the pre-existing test `valid_hosts_and_patterns` (substring match, not a duplicate definition). Gate passed on the first run. | ? |
 | M3a/23-review-fixes | 2026-09-22 | done | 1 | pass | none | Done by the design model, not an implementer run: Ornith was under heavy contention. Findings 1 to 13 and 16 fixed. Tests that failed without their fix cover 1, 2, 3, 4, 7, 8, 9, 10 and 16; two more (a torn first record, an empty later file) passed before the fix and are regression guards; 6, 11 and 13 were checked by reading. 14 moves to M3b's first task; of 15, the log-name rule, `MAX_PATH`'s doc and the unused push are fixed, and the two that change the baseline wait for an epoch change. The server expectations in the device tests were updated to the new layout. | Claude Opus 5.5 |
 | M3a/22-end-to-end | 2026-09-22 | done | 1 | pass | none | Copied `end_to_end.rs`, `Makefile` (workspace build then ignored e2e with `BOXMAKER_BROKERD`) and `tools/check-m3a-device.sh`. Without the variable: 0 passed, 1 ignored. With it: 1 passed five runs. `--ignored` without the variable fails with "set BOXMAKER_BROKERD". `make gate` ran the e2e line (`1 passed`) and prints `gate: ok`. Did not run the straylight script. | Grok 4.6 |