1 Commits

• .NET: Feat/dotnet shell tool (#5604)

  * feat(dotnet): add Microsoft.Agents.AI.Tools.Shell with LocalShellTool
  
  Ports Python LocalShellTool to .NET as a new package (net8/9/10).
  
  - Microsoft.Agents.AI.Tools.Shell: LocalShellTool, ShellPolicy (deny-list
    guardrail), ShellResolver (cross-OS pwsh/powershell/cmd vs bash/sh),
    ShellResult with head+tail truncation, timeout + process-tree kill,
    AsAIFunction with required-by-default human approval gate.
  - Persistent mode via ShellSession (sentinel protocol over pwsh/bash).
  - acknowledgeUnsafe parity gate matches the Python implementation.
  - Auto-injected platform context in the AIFunction description so the
    LLM sees the active OS and shell at tool-discovery time.
  - 17 xunit.v3 tests cover policy allow/deny, echo roundtrip, exit
    codes, timeout/kill, AsAIFunction shape + approval wrapping,
    persistent cwd/env carry-over, head+tail truncation, sentinel race.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * feat(shell): close Python parity gaps for LocalShellTool
  
  Closes the .NET vs Python parity gaps identified in the competitive eval:
  
  - Default mode flipped to ShellMode.Persistent (matches Python). Every
    call now reuses a long-lived shell so cd/exports/functions persist;
    pass mode: ShellMode.Stateless to opt out.
  - New IShellExecutor interface — pluggable backend so future
    DockerShellTool / Hyperlight / SSH executors don't fork the framework.
    LocalShellTool implements it.
  - Workdir confinement: confineWorkingDirectory (default true) re-anchors
    every persistent-mode command back to workingDirectory so a wandering
    cd in one call doesn't leak to the next. Mirrors Python _maybe_reanchor.
  - Graceful interrupt on timeout: ShellSession sends SIGINT (POSIX) or
    Ctrl+C-on-stdin (Windows) before falling back to a hard close+respawn.
    Successfully-interrupted commands return exit 124 + TimedOut=true while
    preserving session state for the next call.
  - cleanEnvironment opt-in: when true, only PATH/HOME/USER/USERNAME/
    USERPROFILE/SystemRoot/TEMP/TMP plus user-supplied vars are visible.
  - shellArgv: IReadOnlyList<string> override accepted alongside the
    string shell binary param (mutually exclusive). Lets advanced callers
    inject flags like --rcfile or --login.
  - Typed exceptions ShellTimeoutException and ShellExecutionException
    replace InvalidOperationException for launch / liveness failures.
  
  Tests: 17 -> 23. New cases cover persistent-default ctor, mutually-
  exclusive shell/shellArgv, confined re-anchor, confine-disabled leak,
  clean-env strip, and IShellExecutor implementation. All green on net10.0.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * feat(shell): add DockerShellTool sandboxed shell tier
  
  Ports the Python DockerShellTool to .NET. Mirrors the public surface of
  LocalShellTool but executes commands inside an isolated container, where
  the container is the security boundary. Stateless and persistent modes
  both supported; persistent mode reuses ShellSession by launching
  'docker exec -i <ctr> bash --noprofile --norc' as the long-lived REPL,
  so the sentinel protocol works unchanged.
  
  Defaults chosen for safety:
  - --network none, --user 65534:65534 (nobody), --read-only root
  - --cap-drop=ALL, --security-opt=no-new-privileges
  - 512m memory cap, pids-limit 256, --tmpfs /tmp
  - Optional host workdir mount, ro by default
  
  Public surface:
  - DockerShellTool ctor with image/container_name/mode/host_workdir/
    workdir/network/memory/pids_limit/user/read_only_root/extra_run_args/
    environment/policy/timeout/max_output_bytes/on_command/docker_binary
  - StartAsync, CloseAsync, RunAsync, AsAIFunction, IShellExecutor impl
  - IsAvailableAsync(binary) probe
  - Static argv builders (BuildRunArgv, BuildExecArgv) — pure, side-
    effect free, so unit tests don't need a Docker daemon
  
  AsAIFunction defaults to requireApproval: false (the container IS the
  boundary). LocalShellTool keeps the opposite default.
  
  Tests: 23 -> 35. 12 new tests cover argv builders, env/extra-args/host-
  workdir flags, exec interactive vs stateless, container name uniqueness,
  IShellExecutor implementation, AsAIFunction approval defaults, and
  IsAvailableAsync false-path. None require Docker. Multi-TFM build
  (net8/9/10) green.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * test(shell): add DockerShellTool integration tests
  
  Adds 9 end-to-end tests that exercise DockerShellTool against a live
  Docker (or Podman) daemon. Tests are tagged [Trait("Category",
  "Integration")] and auto-skip via Assert.Skip when no daemon is
  available, so they are CI-safe.
  
  Coverage:
  - IsAvailableAsync probe
  - Persistent mode basic command + state preservation across calls
  - --network none blocks outbound DNS
  - --read-only root prevents writes outside /tmp; /tmp tmpfs is writable
  - --user 65534:65534 (nobody) is in effect
  - Stateless mode: env vars do not leak across calls
  - HostWorkdir bind-mount + read-only enforcement
  - Environment variables passed via -e
  
  Tests use debian:stable-slim (alpine ships only busybox sh, which
  ShellSession persistent bash REPL cannot drive).
  
  Run locally:
    dotnet test --filter "Category=Integration"
  or filter by class on the test exe directly.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * style(shell): apply dotnet format pass
  
  - Whitespace and code-style fixes from `dotnet format` across both
    projects
  - Convert all new files to UTF-8 with BOM and LF line endings
    (repo convention)
  - Rename ShellSession statics to s_ prefix (IDE1006)
  - Add Async suffix to async test methods (IDE1006)
  
  No behavioral changes. All 44 tests still pass on net10.0; multi-TFM
  build (net8/net9/net10) green. `dotnet format --verify-no-changes`
  now reports clean for both projects.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * docs(shell): add DockerShellTool walkthrough with sequence diagrams
  
  Explains the mental model (we shell out to the docker CLI; we never speak the engine API), the hardened docker run argv, persistent vs stateless lifecycles with mermaid sequence diagrams, the full agent-to-bash call ladder, and the failure modes.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * PR 5604 review fixes (group a): libc DllImport, namespace cleanup, policy-msg dedup
  
  Three quick-win review comments on PR #5604:
  
  1. ShellSession: the libc `killpg` P/Invoke was annotated with
     `DllImportSearchPath.System32`, a Windows-only loader hint that does
     nothing for libc.so on POSIX. Switched to `SafeDirectories` (CA5392
     /CA5393 clean) and added a comment noting the call site is gated to
     non-Windows.
  
  2. DockerShellToolTests: replaced the fully-qualified
     `Extensions.AI.ApprovalRequiredAIFunction` with a `using
     Microsoft.Extensions.AI;` import and the bare type name, matching
     `LocalShellToolTests`.
  
  3. LocalShellTool / DockerShellTool: `AsAIFunction`'s catch block was
     producing a doubled "Command blocked by policy: Command rejected by
     policy: ..." prefix because the `ShellPolicyException` message
     already starts with "Command rejected by policy". Now we return
     `ex.Message` directly.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * PR 5604 review fix (group b): add ShellKind.Sh for /bin/sh fallback
  
  Review comment (#3): when /bin/bash is missing the resolver fell back to
  /bin/sh but tagged it as ShellKind.Bash, so the launcher passed bash-only
  flags --noprofile --norc to dash/ash/busybox, which interpret them as
  positional script names.
  
  Fix:
  
  * Added ShellKind.Sh for minimal POSIX shells (sh, dash, ash, busybox).
  * /bin/sh fallback is now tagged Sh.
  * ClassifyKind maps "SH" / "DASH" / "ASH" / "BUSYBOX" binary names to Sh.
  * StatelessArgvForCommand emits just `-c <command>` for Sh (no
    bash-only flags); PersistentArgv emits no flags at all.
  * LocalShellTool's system-prompt builder describes Sh distinctly and
    warns the model away from bash-only constructs.
  
  Tests: ShellResolverTests covers Sh/Bash classification through the
  observable argv output (14 new theory cases). Total: 58/58.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * PR 5604 review fix (group d): honor timeout=null, add DefaultTimeout
  
  Review comment (#5): both LocalShellTool and DockerShellTool documented
  `timeout: null` as "disables timeouts" but the constructor coerced null
  to 30 seconds, making the documented disable mechanism unreachable
  through the public API.
  
  Fix:
  
  * Drop the `?? TimeSpan.FromSeconds(30)` coercion in both ctors.
    `_timeout` now faithfully reflects what the caller passed (null =
    disabled). The downstream CTS-construction sites already short-circuit
    on null, so no other code changes are required.
  * Add `public static readonly TimeSpan DefaultTimeout` (30 s) on both
    tools so callers who want a bounded timeout can opt in explicitly.
  
  Tests:
  
  * New `RunAsync_NullTimeout_DoesNotTimeOutAsync` confirms a quick
    command runs to completion when the caller passes `timeout: null`.
  * New `DefaultTimeout_IsThirtySeconds` documents the constant.
  
  Behavioral note: this is a deliberate change-of-default. Callers that
  previously omitted `timeout` and relied on the implicit 30 s now get
  "no timeout". They should pass `LocalShellTool.DefaultTimeout` or
  `DockerShellTool.DefaultTimeout` explicitly to preserve the prior
  behavior.
  
  Tests: 60/60 (44 baseline + 14 resolver + 2 new timeout tests).
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * PR 5604 review fix (group e): smart requireApproval default for DockerShellTool
  
  Review comment (#6, design): requireApproval: false baked in a
  safety decision the type cannot prove on its own. Callers can
  weaken any isolation knob (network, user, readOnlyRoot, mount,
  extraRunArgs) and still get an unapproved tool by default.
  
  Fix:
  
  * New public IsHardenedConfiguration property returns true iff the
    effective config matches the safe defaults: network=="none",
    non-root user, read-only root, host mount (if any) read-only,
    no extra run args.
  * AsAIFunction's requireApproval parameter is now bool? defaulting
    to null. When null, approval is enabled iff
    IsHardenedConfiguration is false. Pass false explicitly to opt
    out, or true to force.
  * docker-shell-tool.md updated with the new approval matrix.
  
  Tests: 4 new theory cases + 2 facts cover hardened-default,
  relaxed-network, root-user, writable-root, extraRunArgs, and
  explicit-opt-out branches. Total: 66/66.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * PR 5604 review fix (group c): wrap POSIX shell in setsid for correct killpg
  
  Review comment (#1): killpg(proc.Id, SIGINT) only behaves like a
  process-group signal when proc.Id IS a process group id. Since the
  .NET launcher does not call setsid() / setpgid() itself, the spawned
  shell inherits the agent host's process group — so killpg targeted
  the wrong group and the cancel signal could leak to the agent.
  
  Fix:
  
  * On non-Windows, EnsureStartedAsync probes for setsid (well-known
    paths first, then PATH). When found it wraps the shell launch as
    `setsid <shell> <args...>` so the spawned shell becomes a session
    leader (PID == PGID).
  * A new _isSessionLeader flag tracks whether the wrap succeeded.
  * InterruptCurrentCommandAsync only calls killpg when
    _isSessionLeader is true. Without setsid, killpg on an unsuited
    PID could signal the agent itself, so we skip the fast path and
    let the caller's hard close-and-respawn handle the timeout.
  * Windows behaviour is unchanged (Ctrl+C-via-stdin to pwsh).
  
  No public-API changes; existing tests cover the interrupt path and
  all 66/66 still pass.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * .Net: DockerShellTool design + caller-cancel container leak fixes (PR #5604)
  
  Addresses three Copilot review findings on PR #5604.
  
  Design (group f):
  * StartAsync: change inner ResolvedShell from ShellKind.Bash to ShellKind.Sh.
    BuildExecArgv() already includes `--noprofile --norc` in ExtraArgv;
    Bash's PersistentArgv() was appending those flags a second time,
    yielding `bash --noprofile --norc --noprofile --norc`. Sh's
    PersistentArgv() returns Array.Empty so ExtraArgv is forwarded
    unchanged.
  * BuildExecArgv: remove the dead `interactive: false` branch and the
    `interactive` parameter. The `false` path produced an unusable argv
    ending in `-c` with no command and was never invoked internally
    (stateless mode uses BuildRunArgvStateless). Updated tests and
    docs/docker-shell-tool.md sequence diagram.
  
  Reliability (group g):
  * RunStatelessAsync: add a second `catch (OperationCanceledException)`
    guarded on `cancellationToken.IsCancellationRequested` that issues
    `docker kill --signal KILL <perCallName>` before rethrowing.
    Previously, caller-driven cancellation bypassed the timeout-only
    catch and propagated without killing the container; because `--rm`
    only fires when PID 1 exits, the container ran indefinitely.
    Extracted the kill-by-name logic into a `BestEffortKillContainerAsync`
    helper shared by both the timeout and caller-cancel paths.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * .Net: Fill PR #5604 test coverage gaps for Shell tools
  
  Addresses the test-coverage findings in the latest Copilot review.
  
  * ShellResultTests (new): direct branch coverage for
    ShellResult.FormatForModel() — empty stdout, non-empty stderr,
    truncated, timed-out, success, and the truncated-with-empty-stdout
    edge where the marker is intentionally suppressed. This method's
    string is what the language model sees, so it benefits from
    explicit unit-level coverage independent of integration tests.
  * ShellSessionTests (new): direct unit tests for the internal
    TruncateHeadTail head-tail truncation utility — under-cap (no
    truncation), exactly at cap (no truncation), over-cap (truncated
    with marker, both head and tail preserved), and empty-string.
    Reachable via InternalsVisibleTo.
  * LocalShellToolTests: Theory test exercising 8 representative
    patterns from ShellPolicy.DefaultDenyList (rm -rf /, mkfs.ext4,
    curl|sh, wget|sh, Remove-Item /, shutdown, reboot, Format-Volume)
    to catch deny-list regex regressions; previously only 1/16 was
    tested.
  * LocalShellToolTests: explicit stderr-capture assertion (echo to
    stderr → result.Stderr contains the message). Stderr capture was
    not directly asserted anywhere in the suite.
  * DockerShellToolTests: RunAsync_RejectedCommand throws
    ShellCommandRejectedException. The Docker-side policy check is a
    pure-logic path that runs before any docker invocation, so this
    test covers the rejection branch without needing a Docker daemon.
  
  Total: 66 -> 85 tests, all passing on net10.0.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * feat(dotnet/shell): add ShellEnvironmentProvider for OS-aware shell instructions
  
  Pairs LocalShellTool/DockerShellTool with an AIContextProvider that
  probes the live shell once per session (OS, family, version, CWD,
  configurable CLI versions) and injects authoritative instructions so
  the agent uses platform-native idioms (PowerShell vs POSIX). Fixes the
  class of bugs where the model emits 'VAR=value' / '/tmp' / '$VAR' on
  a Windows PowerShell session.
  
  - ShellEnvironmentProvider/Snapshot/Options public surface in the
    existing Microsoft.Agents.AI.Tools.Shell package (one new project
    reference to Microsoft.Agents.AI.Abstractions).
  - Probes go through the same IShellExecutor that runs agent commands,
    so they respect the configured policy and (for DockerShellTool) the
    container boundary.
  - 8 unit tests covering snapshot capture, default formatter idioms,
    missing-tool handling, custom formatter override, and refresh.
  - Agent_Step21_ShellWithEnvironment sample replays the DEMO_TOKEN
    cross-call scenario using a persistent local shell.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * fix(dotnet/shell): address PR review feedback round 3
  
  - ShellEnvironmentProvider.cs split into one-type-per-file (ShellFamily,
    ShellEnvironmentSnapshot, ShellEnvironmentProviderOptions, plus the
    provider class) to match FoundryMemoryProvider/AgentSkillsProvider
    layout.
  - csproj: drop IsPackable=false (package will publish on merge), add
    IsReleased=true and disable package validation baseline (first release),
    use TargetFrameworksCore, add InjectSharedDiagnosticIds and
    InjectExperimentalAttributeOnLegacy to align with shipping packages.
  - Sample: refactor to demonstrate stateless mode first (independent
    read-only commands), then persistent mode (state carried across calls,
    e.g. DEMO_TOKEN). Strip narrative/historical comments.
  - Move docker-shell-tool.md out of the package — that doc lives in
    the docs repo (semantic-kernel-pr/agent-framework, branch
    feat/dotnet-shell-tool).
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Address PR #5604 round 4 review feedback
  
  - Sample (Agent_Step21_ShellWithEnvironment): add prominent WARNING block
    noting LocalShellTool runs real commands on the host. Restructure sample
    to demonstrate stateless mode first (cd does not carry across calls) then
    persistent mode (cd and env vars persist), motivating when to pick each.
  - DockerShellTool class XML doc: reframe as a best-effort baseline rather
    than a security guarantee; list mitigations users should still apply.
  - DockerShellTool ShellKind.Sh comment: rephrase as forward-looking design
    rationale (avoid duplicate --noprofile/--norc if Bash is reintroduced)
    instead of bug-history narrative.
  - DockerShellTool.IsHardenedConfiguration / AsAIFunction XML docs: clarify
    these are configuration-shape checks and convenience defaults, not
    security guarantees.
  - Drop IDisposable from LocalShellTool and DockerShellTool. The previous
    sync Dispose() blocked on DisposeAsync().GetAwaiter().GetResult() with a
    VSTHRD002 suppression, which is fragile under sync contexts. Both tools
    now expose IAsyncDisposable only; tests updated to await using.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Add Async suffix to async test methods to satisfy IDE1006
  
  Fixes check-format CI failure on PR #5604.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Fix CPU busy-spin in WaitForSentinelAsync
  
  When new bytes arrived in the stdout read loop, the producer called
  TrySetResult on _stdoutSignal but did not replace it with a fresh TCS.
  A consumer looping inside WaitForSentinelAsync would then re-read the
  same already-completed TCS, causing WaitAsync(100ms) to return
  synchronously every iteration — a tight busy-spin that pinned a core
  until the sentinel arrived or the timeout fired.
  
  Swap the signal before completing the old one so the next consumer
  iteration observes a fresh (uncompleted) TCS, matching the pattern
  already used in ReadExitCodeAsync.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Remove unused onCommand audit hook from shell tools
  
  The Action<string> onCommand callback was a redundant audit-logging seam:
  no production callers, no Python parity, and the framework already
  provides function-invocation middleware for cross-cutting concerns at
  the AIFunction layer. Removing the parameter from LocalShellTool and
  DockerShellTool keeps the public surface lean.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Align Shell csproj with Foundry.Hosting preview-package conventions
  
  - Add RootNamespace
  - Move Title/Description into the primary PropertyGroup with
    TargetFrameworks/VersionSuffix to match the Foundry.Hosting layout
  - Drop IsReleased (preview packages do not set it)
  - Drop UTF-8 BOM
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Document why ShellEnvironmentProvider uses Instructions, not Messages
  
  Expand the class XML doc to record the design rationale: the shell
  environment is stable runtime metadata, not per-turn retrieval, so it
  belongs in AIContext.Instructions (matching AgentSkillsProvider).
  Messages is reserved for retrieval payloads (TextSearchProvider,
  ChatHistoryMemoryProvider). System-role placement also has higher
  steering weight and benefits from prompt caching in major providers.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Clarify which probe failures ShellEnvironmentProvider swallows
  
  Name the four exception types explicitly (timeout, policy rejection,
  spawn failure, cancellation) and note that all other exceptions
  propagate normally. Avoids the misleading impression that the provider
  is a blanket try/catch.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Strip cross-language and bug-history narrative from shell tool comments
  
  Remove "hard-won" framing and explicit "Mirrors the Python ..." cross
  references from class XML docs and inline comments in ShellSession,
  DockerShellTool, and ShellResolver. Comments now describe current
  behavior without commentary on prior implementations or development
  history.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Address PR #5604 round 5 review feedback
  
  - ShellResolver: classify only `bash` as ShellKind.Bash; sh/zsh/dash/ash/ksh/busybox now route through ShellKind.Sh so bash-only --noprofile/--norc flags are not emitted to shells that reject them. Update enum doc and tests.
  
  - ShellEnvironmentProvider.ProbeToolVersionAsync: validate the tool name against ^[A-Za-z0-9._-]+$ before interpolating into a shell command (prevents injection if ProbeTools is sourced from untrusted config). Fall back to stderr when stdout is empty so CLIs like java/older gcc still report a version. Drop misleading 'quoted' comment.
  
  - ShellSession.TruncateHeadTail: truncate by UTF-8 byte count on rune boundaries, honouring the documented maxOutputBytes contract for non-ASCII output.
  
  - ShellEnvironmentProviderTests: drop reflection on private _options; assert against the options instance the test already owns. Rename misnamed RefreshAsync test to reflect re-probing semantics. Add coverage for invalid tool names and stderr-only version output.
  
  - ShellSessionTests: add multi-byte UTF-8 truncation tests (byte-budget honoured, no rune split, no U+FFFD).
  
  - Move DockerShellToolIntegrationTests.cs from the unit test project into a new Microsoft.Agents.AI.Tools.Shell.IntegrationTests project so 'dotnet test' on the unit suite no longer requires a Docker daemon. Wire the new project into agent-framework-dotnet.slnx.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Address PR #5604 round 6 review feedback
  
  - ShellSession.MaybeReanchor: switch from double-quoted to single-quoted literal-quoting per shell. Double quotes still expand $VAR, ``, and backticks in both PowerShell and POSIX, so a working directory containing shell metacharacters could trigger command substitution. Add QuotePowerShell (escape ' as '') and QuotePosix (close-and-reopen around ') helpers and route MaybeReanchor through them. Add tests covering ``, $VAR, backticks, and embedded single quotes.
  
  - ShellEnvironmentProvider.RunProbeAsync: narrow the OperationCanceledException filter to `when (!cancellationToken.IsCancellationRequested)` so caller-driven cancellation propagates instead of being silently converted to a null snapshot. Update the class XML doc to call out the distinction. Add tests for both paths (caller cancellation throws, probe-timeout returns null fields).
  
  - DockerShellTool.RunStatelessAsync / RunDockerCommandAsync: replace unbounded StringBuilder accumulators with a shared HeadTailBuffer (extracted from LocalShellTool into its own internal type). Caps memory at roughly maxOutputBytes regardless of how much output a command emits; drops the now-redundant trailing TruncateHeadTail call. RunDockerCommandAsync caps helper-command output at 1 MiB (defends against chatty docker pull progress streams). Add HeadTailBufferTests covering bounded behaviour over 10 MiB of streamed input.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Address PR #5604 round 7 review feedback
  
  - HeadTailBuffer: switch to UTF-8 byte-aware truncation. The class previously
  
    capped on UTF-16 char count while callers pass _maxOutputBytes, so multi-byte
  
    output could exceed the budget and head/tail boundaries could split surrogate
  
    pairs into orphaned halves. Now tracks UTF-8 byte counts and treats each rune
  
    as an indivisible unit (encode -> bytes -> head/tail), guaranteeing the final
  
    string round-trips through UTF-8 and never contains an unpaired surrogate.
  
    The truncation marker now reads `bytes` instead of `chars` to match.
  
  - ShellEnvironmentProvider: clear cached _snapshotTask on failure. Previously a
  
    faulted/cancelled first probe permanently poisoned the provider — every later
  
    ProvideAIContextAsync await replayed the same exception. Now the failed task
  
    is cleared via a CompareExchange so the next caller starts a fresh probe.
  
  Tests: added rune-boundary coverage for HeadTailBuffer, plus two regression
  
  tests for poison-recovery (executor-throw and caller-cancellation paths).
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Address PR #5604 round 8 review feedback
  
  - HeadTailBuffer odd-cap data loss: previously _halfCap = cap / 2 was used as
  
    both the head fill bound and the tail eviction threshold, so an odd cap (e.g.
  
    cap=5 -> halfCap=2) would silently drop a byte while ToFinalString still
  
    reported truncated == false. Split into _headCap = cap / 2 and _tailCap =
  
    cap - _headCap so head + tail budgets always sum to exactly cap; any input
  
    whose UTF-8 size is <= cap now round-trips losslessly.
  
  - ShellSession.TakePrefixByBytes unpaired-high-surrogate: the prefix walker
  
    advanced 2 chars whenever it saw a high surrogate, without verifying that the
  
    next char was actually a low surrogate. Mirrored the pair check from
  
    TakeSuffixByBytes so unpaired surrogates are treated as a single (invalid)
  
    BMP char and the encoder substitutes U+FFFD as it would anywhere else.
  
  - Centralize clean-environment preserved-vars list. The {PATH, HOME, USER,
  
    USERNAME, USERPROFILE, SystemRoot, TEMP, TMP} allowlist was duplicated in
  
    LocalShellTool (stateless launch) and ShellSession (persistent startup), so
  
    adding a new variable required touching both. Extracted into
  
    CleanEnvironmentHelper.PreservedVariables / ApplyPreserved; both call sites
  
    collapse to a single line.
  
  Tests: HeadTailBuffer round-trip-at-odd-cap regression, ShellSession unpaired-
  
  surrogate test.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Address PR #5604 round 9 review feedback
  
  - ShellSession.TruncateHeadTail odd-cap budget: same fix applied to
  
    HeadTailBuffer last round but missed here. Use headCap = cap/2 +
  
    tailCap = cap - headCap so the head/tail budgets sum to exactly cap.
  
  - Replace TakePrefixByBytes / TakeSuffixByBytes Encoder.Convert loops with
  
    rune iteration. The old code ignored Encoder.charsUsed and trusted the
  
    caller's hand-rolled surrogate-pair detection, which made the byte count
  
    fragile around unpaired surrogates. EnumerateRunes + Utf8SequenceLength
  
    is stateless and self-evidently correct.
  
  - ShellEnvironmentProvider.ProbeAsync now skips case-insensitive duplicates
  
    in the user-supplied ProbeTools list. Previously {\"git\",\"GIT\"} would
  
    probe twice and rely on insertion order to determine the kept value.
  
  - DockerShellToolTests.AsAIFunction_RelaxedConfig_DefaultsToApprovalGated:
  
    removed unused trailing ool _ parameter and matching InlineData column.
  
  Tests: added duplicate-ProbeTools regression test.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Address PR #5604 round 10 review feedback
  
  * ShellSession.ReadLoopAsync: replace per-byte buf.Add(chunk[i]) loop with a single buf.AddRange(new ArraySegment<byte>(chunk, 0, n)) bulk copy on the read hot path.
  
  * ShellPolicy: compile allow-list patterns with RegexOptions.IgnoreCase, matching the deny-list and avoiding case-mismatch surprises.
  
  * LocalShellToolTests.RunAsync_NonZeroExit: drop the redundant ternary that selected between two identical 'exit 7' literals.
  
  * DockerShellToolIntegrationTests.NetworkNone: fix the comment to reference 'getent' (matching the actual command) instead of the stale 'wget' phrasing.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * fix(dotnet): address PR #5604 round-3 review feedback
  
  - Rename LocalShellTool/DockerShellTool -> LocalShellExecutor/DockerShellExecutor
  - Rename IShellExecutor.StartAsync/CloseAsync -> InitializeAsync/ShutdownAsync
  - Rename ShellDecision -> ShellPolicyOutcome
  - Rename CleanEnvironmentHelper.ApplyPreserved -> EnvironmentSanitizer.RemoveNonPreserved
  - Convert ShellRequest/ShellPolicyOutcome from record struct to plain readonly struct (with IEquatable<T>)
  - Split ShellMode, ShellTimeoutException, ShellExecutionException into their own files
  - Add DockerNetworkMode static class with None/Bridge/Host constants
  - Convert DockerShellExecutor memory parameter from string to long? memoryBytes
  - Use Throw.IfNull(image) in DockerShellExecutor ctor
  - Make ShellResolver.EnvVarName public const
  - Inline-comment each DefaultDenyList regex; document allow-precedence-over-deny on ShellPolicy.Evaluate
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * fix(dotnet): address PR #5604 round-3 follow-up nits
  
  - DockerShellExecutor / LocalShellExecutor: drop redundant IAsyncDisposable from class declarations (IShellExecutor : IAsyncDisposable already covers it)
  - DockerShellExecutor: scope DefaultImage / DefaultContainerUser / DefaultNetwork / DefaultMemoryBytes / DefaultPidsLimit / DefaultContainerWorkdir to internal (only used as parameter defaults; tests have InternalsVisibleTo)
  - DockerShellExecutor.RunAsync: blank line after the null-guard block (style consistency)
  - csproj: move <Title>/<Description> below the nuget-package.props import so they are not overwritten by the shared defaults; refresh wording to match new executor names
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Refactor shell tool: abstract ShellExecutor, options classes, ContainerUser record
  
  Round-3 review responses for PR #5604:
  
  * Replace IShellExecutor interface with abstract ShellExecutor base class so the surface can be extended without breaking implementers (review feedback from @westey-m).
  
  * Drop ShutdownAsync from the executor surface; DisposeAsync is the canonical teardown (review feedback from @SergeyMenshykh).
  
  * Replace the long parameter lists on Local/DockerShellExecutor constructors with LocalShellExecutorOptions and DockerShellExecutorOptions classes so adding new knobs is no longer a breaking change (review feedback from @SergeyMenshykh).
  
  * Introduce ContainerUser(Uid, Gid) record in place of a 'uid:gid' string for the Docker user, with Default and Root statics (review feedback from @lokitoth).
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Remove IsHardenedConfiguration; AsAIFunction defaults to approval-gated
  
  Addresses PR #5604 review thread AZpMj. The IsHardenedConfiguration
  property was a configuration-shape check, not a security guarantee,
  and using it to auto-disable approval gating gave false confidence.
  
  - Delete IsHardenedConfiguration property.
  - AsAIFunction(requireApproval: null) now always wraps in
    ApprovalRequiredAIFunction; callers must explicitly pass false to
    opt out.
  - Update class- and method-level XML docs to drop hardened-attestation
    language and call out approval gating as the primary safety control.
  - Drop two hardening-assertion tests and the relaxed-config theory;
    add one test asserting null requireApproval is approval-gated.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Replace ShellExecutionException/ShellTimeoutException with standard exceptions
  
  Addresses PR #5604 review threads AaqVP and Aasod. The custom
  exception types added no behavior beyond the base type — only a
  different name — so callers gain nothing from them.
  
  - Delete ShellExecutionException.cs and ShellTimeoutException.cs.
  - Process spawn failures (LocalShellExecutor, DockerShellExecutor)
    and broken-pipe to a long-lived shell (ShellSession) now throw
    IOException, which is the natural .NET shape for these failures.
  - ShellTimeoutException was declared but never thrown; the only
    in-process timeout path uses the OperationCanceledException raised
    by the linked CancellationTokenSource. The catch-and-swallow in
    ShellEnvironmentProvider now matches IOException + TimeoutException.
  - Update XML doc comments accordingly.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Remove ShellPolicy.DefaultDenyList; default policy is empty
  
  Addresses PR #5604 review thread AY7Ba. A regex deny-list is
  bypassed in seconds by hex escapes ($(echo -e "\x72\x6D")),
  command substitution ($(base64 -d <<<...)), and envvar splicing
  ($(A=r B=m; echo $A$B)). No major agent framework uses regex
  matching as a primary control; AutoGen explicitly removed theirs
  in v2. The real defenses are approval gating (default) and the
  Docker sandbox tier.
  
  - Delete DefaultDenyList property from ShellPolicy.
  - ShellPolicy(denyList: null) now means an empty deny-list.
  - Rewrite ShellPolicy class XML docs to frame as a UX pre-filter
    for operator-supplied patterns, not as a security control.
  - Update LocalShellExecutorOptions/DockerShellExecutorOptions
    Policy docs to match.
  - Tests that exercise the deny-list mechanism now supply patterns
    explicitly, mirroring real operator usage.
  - Add Policy_DefaultConstruction_AllowsAnyNonEmptyCommand test.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  * Document single-session ownership for persistent shell mode
  
  Several PR #5604 review threads (notably AaQh2) raised that the persistent
  shell experience has no concurrency story. The framework's actual design
  is "one executor per conversation" — there is no per-caller isolation —
  but that contract was only stated briefly on ShellExecutor and not at all
  on the types and properties developers reach for first.
  
  Strengthen the docs in the places a user is most likely to land:
  
  - ShellMode.Persistent: explicit single-session-ownership paragraph
    (state visible across calls, single pipe, no isolation, one per session).
  - ShellExecutor: rewrite the Concurrency paragraph to enumerate what
    leaks (cwd, env, history, background jobs) and call out DI scoping.
  - LocalShellExecutor: new Single-session-ownership paragraph mirroring
    the executor-level contract and pointing at Stateless mode as the
    escape hatch.
  - DockerShellExecutor: same, framed around the container + bash REPL
    the persistent-mode executor owns end-to-end.
  - ShellSession: add a Single-owner paragraph on the type docs and a
    comment on _runLock clarifying that it serializes the owner's calls,
    not multiple tenants.
  - LocalShellExecutorOptions.Mode / DockerShellExecutorOptions.Mode:
    per-property note pointing at the executor remarks.
  
  Docs-only; src builds clean with zero warnings, zero errors.
  
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
  
  ---------
  
  Co-authored-by: alliscode <bentho@microsoft.com>
  Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

  Ben Thomas · 2026-05-12 16:17:49 +00:00
  4409b00b86