Retire pre-v0.9 runtime compatibility vestiges

[Gudge (MGudgin)]

📖 Description

This PR removes pre-v0.9 compatibility from request normalization and backend execution. It deletes redundant default-environment and network markers, unreachable host-list/proxy paths, the built-in test proxy, and obsolete CLI testing switches while preserving directional enforcement and caller-managed proxy behavior. It also redacts non-string proxy values before diagnostics are logged.

Details

• Remove old-version paths in Windows, VM, LXC, Bubblewrap, and Seatbelt backends.
• Drop unrepresentable shared runtime fields and retired proxy/testing plumbing.
• Preserve immutable published schemas, supported external proxies, and network audits.
• Redact non-string proxy diagnostics and clarify supported networking guidance.

🔗 References

Alternative to the stacked sequence #1421, #1422, #1423, #1424, and #1426. Merge this PR or the stack, not both. Follows #1382 and #1383.

🔍 Validation

Tests

• From src/, cargo fmt --all -- --check: passed.
• cargo check --workspace --all-targets --all-features --quiet: passed.
• cargo clippy --workspace --all-targets --all-features --quiet -- -D warnings: passed.
• cargo test --workspace --quiet: passed.
• cargo test -p mxc-sdk --lib --features wslc,isolation_session,microvm,hyperlight --quiet: 3,293 passed, 3 ignored.
• cargo test -p mxc-sdk --lib non_string_proxy_values_in_comments_are_redacted --quiet: 1 passed on Windows.
• cargo check -p mxc-sdk --all-targets --target x86_64-apple-darwin --quiet: passed.
• Debian WSL, from src/, cargo check -p mxc-sdk --all-targets --quiet: passed.
• Debian WSL, cargo test -p mxc-sdk --lib lxc::common --quiet -- --test-threads=1: 302 passed.
• Debian WSL, cargo test -p mxc-sdk --lib bubblewrap::common --quiet -- --test-threads=1: 301 passed.
• Debian WSL, cargo build -p lxc -p unix_test_proxy --quiet: passed; bash ../tests/scripts/run_bwrap_directional_test.sh: nine checks passed.
• node --test scripts/versioning/tests/check-contract-codegen.test.js: 9 passed; node scripts/versioning/check-contract-codegen.js --check: passed on the combined commit.
• Native macOS execution and live LXC container tests were not run locally.

✅ Checklist

• Signed the Contributor License Agreement
• Linked to an issue
• Updated documentation (if applicable)
• Updated Copilot instructions (if build, architecture, or conventions changed)
• If this PR changes Cargo.lock, the dependency-feed-check check passes (see docs/pull-requests.md)

📋 Issue Type

• Bug fix
• Feature
• Task

---

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Microsoft Reviewers: Open in CodeFlow

[azure-pipelines]

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[Gudge (MGudgin)]

Follow-up on October 5, 2026 (PR head 566c850): Reverified the 18 filed findings: 16 addressed, the retired-schema deletion concern (#14 in the attribution ledger) is moot after restoring those artifacts and clarifying the rule, and the backend-guide claim (#22) is only partially addressed. The LXC guide is fixed, but the Bubblewrap guide still claims impossible direct-request runtime rejections; that remaining portion has a new inline comment at docs/bwrap-support/bubblewrap-backend.md:16 (comment 4189887434). The unchanged NanVix roadmap parenthetical from the broader source review now has its own general PR comment (6005307614).

All nine original review threads were already resolved when checked. The review below describes the earlier 7a2c10f tree and is retained as historical evidence; its findings are not all currently open.

---

Review summary

Reviewed the fetched 7a2c10f head against the PR's 058b5c5 base, including the 119-file diff and nearby tests. No attributable High-severity security or policy-enforcement issue was established. ScriptRunner::run already validates Hyperlight requests before execute (src/core/wxc_common/src/script_runner.rs:32-48); omitted-network deny defaults remain in the touched backends; validateStableHistory still rejects edits/removals of retained published schemas, with floor-boundary tests at scripts/versioning/tests/check-contract-codegen.test.js:233-265. No third-party dependency was added. This is a COMMENT review, not a request to block the draft.

Findings without an added-line anchor

• Medium (documentation drift) — deleted networking specification still has readers. docs/process-container/networking.md:254 says to see "the parent doc on the last 4"; docs/bwrap-support/bubblewrap-backend.md:386-387 invokes the GA networking spec, and docs/schema.md:47,55 refers to its shared model-2 policy. Attribution: newly_exposed_by_change — this PR deletes docs/sandbox-policy/0.8.0/networking/networking.md, making these retained references unusable. Fix: Move the needed connectivity-model/out-of-scope explanation to retained documentation and point these references there.
• Low (simplicity) — AppContainer NetworkManager is now a forwarding layer. src/backends/process_container/common/src/network_manager.rs:12-53 contains only ProxyCoordinator, forwards proxy_address/stop_all, and checks enablement before forwarding start. Attribution: newly_exposed_by_change — removing the firewall implementation leaves the existing layer without a separate resource responsibility. Fix: Own the coordinator directly at its one production caller, keeping the enablement check.
• Low (simplicity) — LXC retains a hostname-expansion pipeline for CIDRs. src/backends/lxc/common/src/network_iptables.rs:97-113,579-610 still holds ResolvedDestinations vectors and formats/reparses destination strings after this PR removes hostname expansion. Attribution: newly_exposed_by_change — the multi-address case that justified these structures is gone. Fix: Carry typed CIDR/family through lowering and remove the redundant resolution stage.
• Low (release instructions) — the stable-schema deletion exception is documented inconsistently. .github/copilot-instructions.md:77 still says never edit schemas/stable/, while this PR deliberately deletes three below-floor files and docs/versioning.md:161-164 now permits below-floor deletion. Attribution: introduced_by_change — the exception and deleted artifacts are new; the unchanged instruction now conflicts with them. Fix: If below-floor deletion is approved, update the contributor instruction to distinguish removal of retired artifacts from mutation of retained schemas.
• Low (maintainability) — an orphaned doc comment describes the wrong field. src/core/wxc_common/src/models.rs:949-951 now places "Whether backends supply the default process.env block" above container_id. Attribution: introduced_by_change — removing the compatibility field stranded its old comment. Fix: Remove that line.
• Low (maintainability) — dead host-list error constant. src/core/wxc_common/src/error.rs:66-70 is byte-identical to the base, but HOST_LISTS_NOT_SUPPORTED_MSG lost both call sites in this PR and still describes retired allowedHosts/defaultPolicy fields. Attribution: newly_exposed_by_change — the PR removed its remaining users. Fix: Delete the constant.
• Low (documentation) — remaining legacy vocabulary in WSLc diagnostics and roadmap. src/backends/wslc/common/src/wsl_container_runner.rs:896-910 still tells direct callers to supply network.proxy's URL form rather than runtimeConfig.networkProxy, and docs/linux-wsl-roadmap-june-2026.md:341 says removed WSLc rule builders are "retained". Attribution: newly_exposed_by_change — the wire forms and functions these unchanged lines describe were removed by this PR; the roadmap is byte-identical to the base, while the WSLc message survives unchanged inside a modified file. Fix: Update the diagnostic and roadmap to match supported policy and removed implementation.
• Low (documentation) — workflow and .NET source comments retain retired labels. .github/workflows/Build.Linux.Job.yml:181-183 still calls the test proxy builtinTestServer; sdk/dotnet/Microsoft.Mxc.Sdk/V1/ContainerRequestSections.cs:181,197,209 still labels the directional fields schema 0.8 while this PR updates the generated reference to supported directional policy. Attribution: newly_exposed_by_change — these byte-identical comments become misleading after the built-in proxy/schema retirement. Fix: Update the workflow and XML docs along with the reference.

Verified pre-existing; not attributed to this PR

• Windows direct-request proxy fallback (src/backends/process_container/common/src/base_container_runner.rs:347-350) and Bubblewrap remote-proxy resolution (src/backends/bubblewrap/common/src/proxy_network.rs:343-379) are already present at the base without a newly reachable path established here.
• The old authoring-guide pointer to nonexistent createConfigFromPolicy() predates this PR; its new link accurately promises only the supported request shape.
• Historical Windows Firewall rules could already outlive a crash or intentionally preserved policy; the old manager tracked only rules created during its own lifetime, so this PR does not establish a new upgrade-only failure.

The GitHub combined diff endpoint returned HTTP 406 (>20,000 lines). The review uses the fetched PR head, whose OID and merge-base exactly match GitHub's head/base metadata. Inline anchors below were checked against added lines in that local PR diff. No host-dependent runtime tests were run for this attribution pass.

[Copilot]

Copilot wasn't able to review this pull request because it exceeds the maximum number of lines (20,000). Try reducing the number of changed lines and requesting a review from Copilot again.

[Copilot]

Copilot review overview

🔵 Needs a closer look

Cross-platform network enforcement and cleanup changes need final human review supported by native-host validation.

Review effort: Balanced
Findings: 1

Open (1)

• AppContainer network success is recorded before process launch · New

[Gudge (MGudgin)]

Addressed the unanchored findings from the review summary:

• Restored the connectivity-model and out-of-scope explanation in supported documentation, corrected the retired typed-request claims, and updated the WSLc diagnostic/roadmap and Linux workflow/.NET comments (ad4862ddb, a3b604bf1).
• Removed the ownerless Unix proxy coordinator and forwarding-only AppContainer network manager; lowered LXC rules as typed CIDRs (192f929a8, 59e0403fa, a3b604bf1).
• Clarified the published-schema retention rule, removed the orphaned model comment and unused host-list error, and distinguished AppContainer from BaseContainer network-audit timing (fcdcce53d, ad4862ddb, 566c85027).
• As requested later, restored the v0.6-v0.8 JSON schemas byte-for-byte (2f96b17c1); the historical docs/sandbox-policy/ guides remain removed. The contract-codegen gate passes with the schemas restored.

I replied to and resolved the nine anchored review threads separately. The latest executable tree passed local workspace/Linux checks and the native macOS job on the prior head; the subsequent commits affect only schema artifacts and documentation.

[Copilot]

Copilot review overview

🔵 Needs a closer look

Security-sensitive cross-platform networking and cleanup changes need human review of native-host validation, including the untested live LXC path.

Review effort: Balanced
Findings: None

Resolved since last review (1)

• AppContainer network success is recorded before process launch

[Copilot]

Copilot review overview

🔵 Needs a closer look

Cross-platform network enforcement and proxy lifecycle changes need final human review with the pending native-host validation results.

Review effort: Balanced
Findings: None

[Gudge (MGudgin)]

Low (documentation drift) — NanVix's roadmap comparison still names a removed egress filter. docs/linux-wsl-roadmap-june-2026.md:515 says NanVix has a "per-guest egress filter". This PR removes the NanVix allow/block host-list filter and its guest-filter flags (src/backends/nanvix/runner/src/lib.rs); the current backend accepts only the supported all-deny or unrestricted directional posture, not per-destination egress filtering.

Attribution: newly_exposed_by_change — the unchanged roadmap sentence becomes inaccurate because this PR removes the filter. The per-guest scoping point remains valid: each guest has its own VM. Fix: retain that per-guest scoping explanation, but remove the filter claim or describe the current all-or-nothing network posture.

This sentence is outside the PR's added lines, so I am leaving it as a general comment rather than forcing an inline anchor. The previously filed WSLc roadmap observation has been addressed separately.

[Gudge (MGudgin)]

Addressed the NanVix roadmap comment (6005307614) in 521eb53. The comparison now retains per-guest scoping but describes NanVix networking as coherent all-deny or unrestricted; it no longer claims a per-destination egress filter. The same sentence also reflects Hyperlight networking under supported contracts.

[Copilot]

Copilot review overview

🔵 Needs a closer look

Cross-platform enforcement changes require human review, especially with an unresolved redaction flaw and unexecuted live LXC/macOS validation.

Review effort: Balanced
Findings: 1

Open (1)

• Prevent secrets leaking through non-string comment values · New

[Copilot]

Copilot review overview

🔵 Needs a closer look

Cross-platform sandbox networking and proxy ownership changes warrant human review, especially with native macOS and live LXC runtime validation not run locally.

Review effort: Balanced
Findings: 1 · 2

Open (3)

• Prevent secrets leaking through non-string comment values
• Clarify WSLc all-allow support versus independent ingress filtering · New
• Correct WSLc networking example to use all-allow posture · New

[Copilot]

Copilot review overview

🔵 Needs a closer look

Cross-platform network-enforcement changes warrant human review, with native macOS and live LXC runtime validation still unreported.

Review effort: Balanced
Findings: 1 · 3

Open (4)

• Prevent secrets leaking through non-string comment values
• Clarify network sections must be omitted for default isolation · New
• Correct WSLc networking example to use all-allow posture
• Clarify WSLc all-allow support versus independent ingress filtering

[Copilot]

Copilot review overview

🔵 Needs a closer look

Cross-platform enforcement changes warrant human review, particularly with native macOS and live LXC execution unvalidated locally.

Review effort: Balanced
Findings: 1 · 4

Open (5)

• Prevent secrets leaking through non-string comment values
• Document omitted-network egress default as deny · New
• Clarify network sections must be omitted for default isolation
• Correct WSLc networking example to use all-allow posture
• Clarify WSLc all-allow support versus independent ingress filtering

[Copilot]

Copilot review overview

🔵 Needs a closer look

Cross-platform network-enforcement changes need human review, particularly with live LXC and native macOS validation outstanding.

Review effort: Balanced
Findings: 1

Open (1)

• Clarify runtime-proxy fallback is unsupported without BaseContainer/PSEC · New

Resolved since last review (5)

• Prevent secrets leaking through non-string comment values
• Document omitted-network egress default as deny
• Clarify network sections must be omitted for default isolation
• Correct WSLc networking example to use all-allow posture
• Clarify WSLc all-allow support versus independent ingress filtering

[Copilot]

Copilot review overview

🔵 Needs a closer look

Cross-platform isolation changes warrant human review, especially with native macOS and live LXC execution not validated locally.

Review effort: Balanced
Findings: 1

Open (1)

• Clarify runtime-proxy fallback is unsupported without BaseContainer/PSEC

[Copilot]

Copilot review overview

🔵 Needs a closer look

Cross-platform network enforcement changes warrant human review, particularly with native macOS and live LXC validation still outstanding.

Review effort: Balanced
Findings: 1

Open (1)

• Clarify runtime-proxy fallback is unsupported without BaseContainer/PSEC

[Branden Bonaby (bbonaby)]

thank you for this!