feat: add transaction context crate

[bmuddha]

What changed

Customized the imported solana-transaction-context baseline for the engine's
account representation and patched the crate into the workspace.

Why

VM handlers need to remap account data on writes through a mapped region instead
of copying through a serialized input buffer.

Closes #10.

Impact

• Reshapes TransactionContext, InstructionContext, and
  TransactionAccounts around AccountRef and AccountRefMut views.
• Keeps accounts in UnsafeCell behind explicit borrow counters so borrows stay
  local to the context.
• Returns keyed accounts, return data, touched-account count, and resize deltas
  through ExecutionRecord.

Reviewer notes

Borrow counters are released on drop; outstanding references must be gone before
a context is deconstructed. The mapped-account divergences are documented in
solana/README.md.

Follow-up

program-runtime and svm consume this customized context upstack.

[bmuddha]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• feat: protect authoritative accounts from overwrites #37
• feat: add state replicator crate on top of the engine #25
• feat: adds top level engine crate for global orchestration #24
• feat: added internal built-in magic root program #23
• feat: implement transaction processor crate #22
• feat: implements keeper crate - state orchestrator #17
• feat: implement superblock based ledger crate #15
• feat: add optimized accountsdb crate #14
• feat: add nucleus engine crate #18
• feat: add svm crate #21
• feat: add program runtime crate #20
• feat: add transaction context crate #19 👈 (View in Graphite)
• feat: forked transaction-view for increased limits #33
• feat: add customized solana-account crate #13
• chore: import upstream Solana runtime crates #31
• dev

This stack of pull requests is managed by Graphite. Learn more about stacking.

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Walkthrough

The forked solana-transaction-context crate is integrated into the workspace. It now uses unified account storage, direct account views, updated CPI trace accounting, explicit resize restrictions, and direct account-region remapping.

Changes

Transaction context fork

Layer / File(s)	Summary
Workspace and crate integration Cargo.toml, solana/transaction-context/Cargo.toml, solana/transaction-context/README.md, solana/transaction-context/src/lib.rs	The workspace registers the crate and updates Solana and Agave dependencies. Crate metadata, features, documentation, and lint settings now use workspace-compatible values.
Unified account storage and views solana/transaction-context/src/transaction_accounts.rs	TransactionAccounts stores AccountSharedData directly. Immutable and mutable views use dereferencing and copy-on-write borrowing. Deconstruction preserves account metadata and dirty markers.
Account access and resize rules solana/transaction-context/src/instruction.rs, solana/transaction-context/src/instruction_accounts.rs	Program ownership uses direct account borrowing. Borrowed CoW accounts count as shared. Ephemeral-account resizing returns InvalidRealloc.
Instruction trace and memory execution solana/transaction-context/src/transaction.rs, solana/transaction-context/src/vm_slice.rs	Instruction execution uses placeholder frames, sequential trace indices, explicit CPI and total-trace limits, active-instruction counting, and direct remapping after account growth. Tests cover the revised trace and CPI behavior.

Estimated code review effort: 4 (Complex) | ~60 minutes

Possibly related issues

• Issue 32 — The PR modifies the same imported solana/transaction-context crate described by the issue.

Possibly related PRs

• magicblock-labs/magicblock-engine#31 — Both PRs modify solana/transaction-context; this PR further changes its account, instruction, memory, and transaction-context implementations.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 58.54% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the primary change: adding the customized transaction context crate.
Description check	✅ Passed	The description explains the crate fork, engine account model changes, mapped writes, and workspace integration.
Linked Issues check	✅ Passed	The changes fork and adapt solana-transaction-context for engine execution and its account representation as required by issue [#10].
Out of Scope Changes check	✅ Passed	The workspace, documentation, dependency, account model, and transaction context changes support the linked issue objectives.

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• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch transaction-context

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[bmuddha]

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Actionable comments posted: 1

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

solana/transaction-context/src/instruction_accounts.rs (1)

226-243: 🎯 Functional Correctness | 🟠 Major | ⚡ Quick win

Use is_shared() with borrowed accounts and update the reserve behavior.

make_data_mut() currently skips borrowed accounts, so get_data_mut() and extend_from_slice() can trigger borrowed-to-owned promotion later. CoWAccount::reserve() keeps the borrowed image when spare() is enough, so replace AccountSharedData::is_shared() with self.is_shared() and update the stale “second-copy” comment unless the reserve path always promotes.

🔧 Proposed fix if borrowed images need the reserve

-        if self.account.is_shared() {
+        if self.is_shared() {
             self.account.reserve(MAX_ACCOUNT_DATA_GROWTH_PER_INSTRUCTION);
         }

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@solana/transaction-context/src/instruction_accounts.rs` around lines 226 -
243, Update make_data_mut() to use the InstructionAccount::is_shared() helper,
so both shared buffers and borrowed CoWAccount variants enter the reserve path.
Revise the nearby comment to accurately describe the reserve behavior and remove
the stale claim about avoiding a second copy unless CoWAccount::reserve() is
guaranteed to promote borrowed images.

🧹 Nitpick comments (1)

solana/transaction-context/src/transaction_accounts.rs (1)

188-199: 📐 Maintainability & Code Quality | 🔵 Trivial | 💤 Low value

Both deconstruct methods drain the same storage.

deconstruct_into_keyed_account_shared_data and deconstruct_into_account_shared_data both call std::mem::take(&mut self.accounts). After the first call the array is empty, so the second call returns an empty Vec without any error. borrow_counters and touched_flags keep their original length, so len() and index-based access become inconsistent with the storage.

Consider making the drain explicit at the type level, or add a debug assertion that the storage is still populated.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@solana/transaction-context/src/transaction_accounts.rs` around lines 188 -
199, Update deconstruct_into_keyed_account_shared_data and
deconstruct_into_account_shared_data to make draining self.accounts explicit and
prevent silent repeated deconstruction; ensure the second call cannot return an
empty result while borrow_counters and touched_flags retain stale lengths,
either through a consumed-state representation or a debug assertion before
draining.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@solana/transaction-context/src/transaction_accounts.rs`:
- Around line 152-156: Update try_borrow_mut so it projects directly to the
KeyedAccountSharedData tuple’s account field (.1) from the UnsafeCell pointer,
rather than first creating a mutable reference to the whole keyed account. Keep
AccountRefMut and borrow-counter behavior unchanged while ensuring the mutable
borrow excludes the key field.

---

Outside diff comments:
In `@solana/transaction-context/src/instruction_accounts.rs`:
- Around line 226-243: Update make_data_mut() to use the
InstructionAccount::is_shared() helper, so both shared buffers and borrowed
CoWAccount variants enter the reserve path. Revise the nearby comment to
accurately describe the reserve behavior and remove the stale claim about
avoiding a second copy unless CoWAccount::reserve() is guaranteed to promote
borrowed images.

---

Nitpick comments:
In `@solana/transaction-context/src/transaction_accounts.rs`:
- Around line 188-199: Update deconstruct_into_keyed_account_shared_data and
deconstruct_into_account_shared_data to make draining self.accounts explicit and
prevent silent repeated deconstruction; ensure the second call cannot return an
empty result while borrow_counters and touched_flags retain stale lengths,
either through a consumed-state representation or a debug assertion before
draining.

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📥 Commits

Reviewing files that changed from the base of the PR and between 86c2748 and 017643e.

📒 Files selected for processing (10)

• Cargo.toml
• solana/transaction-context/Cargo.toml
• solana/transaction-context/README.md
• solana/transaction-context/src/instruction.rs
• solana/transaction-context/src/instruction_accounts.rs
• solana/transaction-context/src/lib.rs
• solana/transaction-context/src/transaction.rs
• solana/transaction-context/src/transaction_accounts.rs
• solana/transaction-context/src/vm_addresses.rs
• solana/transaction-context/src/vm_slice.rs

💤 Files with no reviewable changes (1)

• solana/transaction-context/src/vm_addresses.rs